Fukushima Nuclear Accident – a simple and accurate explanation

Twitter updates: @BraveNewClimate

New 15 MarchFukushima Nuclear Accident – 15 March summary of situation

New 14 MarchUpdates and additional Q&A information here and Technical details here

福島原発事故-簡潔で正確な解説 (version 3):(東京大学エンジニアリング在学生の翻訳) (thanks to Shota Yamanaka for translation)

Other translations: Italian, Spanish, German, 普通话


Along with reliable sources such as the IAEA and WNN updates, there is an incredible amount of misinformation and hyperbole flying around the internet and media right now about the Fukushima nuclear reactor situation. In the BNC post Discussion Thread – Japanese nuclear reactors and the 11 March 2011 earthquake (and in the many comments that attend the top post), a lot of technical detail  is provided, as well as regular updates. But what about a layman’s summary? How do most people get a grasp on what is happening, why, and what the consequences will be?

Below I reproduce a summary on the situation prepared by Dr Josef Oehmen, a research scientist at MIT, in Boston. He is a PhD Scientist, whose father has extensive experience in Germany’s nuclear industry. This was first posted by Jason Morgan earlier this evening, and he has kindly allowed me to reproduce it here. I think it is very important that this information be widely understood.

Please also take the time to read this: An informed public is key to acceptance of nuclear energy — it was never more relevant than now.


NOTE: Content Updated 15 March, see: http://mitnse.com/

We will have to cover some fundamentals, before we get into what is going on.

Construction of the Fukushima nuclear power plants

The plants at Fukushima are Boiling Water Reactors (BWR for short). A BWR produces electricity by boiling water, and spinning a a turbine with that steam. The nuclear fuel heats water, the water boils and creates steam, the steam then drives turbines that create the electricity, and the steam is then cooled and condensed back to water, and the water returns to be heated by the nuclear fuel. The reactor operates at about 285 °C.

The nuclear fuel is uranium oxide. Uranium oxide is a ceramic with a very high melting point of about 2800 °C. The fuel is manufactured in pellets (cylinders that are about 1 cm tall and 1 com in diameter). These pellets are then put into a long tube made of Zircaloy (an alloy of zirconium) with a failure temperature of 1200 °C (caused by the auto-catalytic oxidation of water), and sealed tight. This tube is called a fuel rod. These fuel rods are then put together to form assemblies, of which several hundred make up the reactor core.

The solid fuel pellet (a ceramic oxide matrix) is the first barrier that retains many of the radioactive fission products produced by the fission process.  The Zircaloy casing is the second barrier to release that separates the radioactive fuel from the rest of the reactor.

The core is then placed in the pressure vessel. The pressure vessel is a thick steel vessel that operates at a pressure of about 7 MPa (~1000 psi), and is designed to withstand the high pressures that may occur during an accident. The pressure vessel is the third barrier to radioactive material release.

The entire primary loop of the nuclear reactor – the pressure vessel, pipes, and pumps that contain the coolant (water) – are housed in the containment structure.  This structure is the fourth barrier to radioactive material release. The containment structure is a hermetically (air tight) sealed, very thick structure made of steel and concrete. This structure is designed, built and tested for one single purpose: To contain, indefinitely, a complete core meltdown. To aid in this purpose, a large, thick concrete structure is poured around the containment structure and is referred to as the secondary containment.

Both the main containment structure and the secondary containment structure are housed in the reactor building. The reactor building is an outer shell that is supposed to keep the weather out, but nothing in. (this is the part that was damaged in the explosions, but more to that later).

Fundamentals of nuclear reactions

The uranium fuel generates heat by neutron-induced nuclear fission. Uranium atoms are split into lighter atoms (aka fission products). This process generates heat and more neutrons (one of the particles that forms an atom). When one of these neutrons hits another uranium atom, that atom can split, generating more neutrons and so on. That is called the nuclear chain reaction. During normal, full-power operation, the neutron population in a core is stable (remains the same) and the reactor is in a critical state.

It is worth mentioning at this point that the nuclear fuel in a reactor can never cause a nuclear explosion like a nuclear bomb. At Chernobyl, the explosion was caused by excessive pressure buildup, hydrogen explosion and rupture of all structures, propelling molten core material into the environment.  Note that Chernobyl did not have a containment structure as a barrier to the environment. Why that did not and will not happen in Japan, is discussed further below.

In order to control the nuclear chain reaction, the reactor operators use control rods. The control rods are made of boron which absorbs neutrons.  During normal operation in a BWR, the control rods are used to maintain the chain reaction at a critical state. The control rods are also used to shut the reactor down from 100% power to about 7% power (residual or decay heat).

The residual heat is caused from the radioactive decay of fission products.  Radioactive decay is the process by which the fission products  stabilize themselves by emitting energy in the form of small particles (alpha, beta, gamma, neutron, etc.).  There is a multitude of fission products that are produced in a reactor, including cesium and iodine.  This residual heat decreases over time after the reactor is shutdown, and must be removed by cooling systems to prevent the fuel rod from overheating and failing as a barrier to radioactive release. Maintaining enough cooling to remove the decay heat in the reactor is the main challenge in the affected reactors in Japan right now.

It is important to note that many of these fission products decay (produce heat) extremely quickly, and become harmless by the time you spell “R-A-D-I-O-N-U-C-L-I-D-E.”  Others decay more slowly, like some cesium, iodine, strontium, and argon.

What happened at Fukushima (as of March 12, 2011)

The following is a summary of the main facts. The earthquake that hit Japan was several times more powerful than the worst earthquake the nuclear power plant was built for (the Richter scale works logarithmically; for example the difference between an 8.2 and the 8.9 that happened is 5 times, not 0.7).

When the earthquake hit, the nuclear reactors all automatically shutdown. Within seconds after the earthquake started, the control rods had been inserted into the core and the nuclear chain reaction stopped. At this point, the cooling system has to carry away the residual heat, about 7% of the full power heat load under normal operating conditions.

The earthquake destroyed the external power supply of the nuclear reactor. This is a challenging accident for a nuclear power plant, and is referred to as a “loss of offsite power.” The reactor and its backup systems are designed to handle this type of accident by including backup power systems to keep the coolant pumps working. Furthermore, since the power plant had been shut down, it cannot produce any electricity by itself.

For the first hour, the first set of multiple emergency diesel power generators started and provided the electricity that was needed. However, when the tsunami arrived (a very rare and larger than anticipated tsunami) it flooded the diesel generators, causing them to fail.

One of the fundamental tenets of nuclear power plant design is “Defense in Depth.” This approach leads engineers to design a plant that can withstand severe catastrophes, even when several systems fail. A large tsunami that disables all the diesel generators at once is such a scenario, but the tsunami of March 11th was beyond all expectations. To mitigate such an event, engineers designed an extra line of defense by putting everything into the containment structure (see above), that is designed to contain everything inside the structure.

When the diesel generators failed after the tsunami, the reactor operators switched to emergency battery power. The batteries were designed as one of the backup systems to provide power for cooling the core for 8 hours. And they did.

After 8 hours, the batteries ran out, and the residual heat could not be carried away any more.  At this point the plant operators begin to follow emergency procedures that are in place for a “loss of cooling event.” These are procedural steps following the “Depth in Defense” approach. All of this, however shocking it seems to us, is part of the day-to-day training you go through as an operator.

At this time people started talking about the possibility of core meltdown, because if cooling cannot be restored, the core will eventually melt (after several days), and will likely be contained in the containment. Note that the term “meltdown” has a vague definition. “Fuel failure” is a better term to describe the failure of the fuel rod barrier (Zircaloy).  This will occur before the fuel melts, and results from mechanical, chemical, or thermal failures (too much pressure, too much oxidation, or too hot).

However, melting was a long ways from happening and at this time, the primary goal was to manage the core while it was heating up, while ensuring that the fuel cladding remain intact and operational for as long as possible.

Because cooling the core is a priority, the reactor has a number of independent and diverse cooling systems (the reactor water cleanup system, the decay heat removal, the reactor core isolating cooling, the standby liquid cooling system, and others that make up the emergency core cooling system). Which one(s) failed when or did not fail is not clear at this point in time.

Since the operators lost most of their cooling capabilities due to the loss of power, they had to use whatever cooling system capacity they had to get rid of as much heat as possible. But as long as the heat production exceeds the heat removal capacity, the pressure starts increasing as more water boils into steam. The priority now is to maintain the integrity of the fuel rods by keeping the temperature below 1200°C, as well as keeping the pressure at a manageable level. In order to maintain the pressure of the system at a manageable level, steam (and other gases present in the reactor) have to be released from time to time. This process is important during an accident so the pressure does not exceed what the components can handle, so the reactor pressure vessel and the containment structure are designed with several pressure relief valves. So to protect the integrity of the vessel and containment, the operators started venting steam from time to time to control the pressure.

As mentioned previously, steam and other gases are vented.  Some of these gases are radioactive fission products, but they exist in small quantities. Therefore, when the operators started venting the system, some radioactive gases were released to the environment in a controlled manner (ie in small quantities through filters and scrubbers). While some of these gases are radioactive, they did not pose a significant risk to public safety to even the workers on site. This procedure is justified as its consequences are very low, especially when compared to the potential consequences of not venting and risking the containment structures’ integrity.

During this time, mobile generators were transported to the site and some power was restored.  However, more water was boiling off and being vented than was being added to the reactor, thus decreasing the cooling ability of the remaining cooling systems. At some stage during this venting process, the water level may have dropped below the top of the fuel rods.  Regardless, the temperature of some of the fuel rod cladding exceeded 1200 °C, initiating a reaction between the Zircaloy and water. This oxidizing reaction produces hydrogen gas, which mixes with the gas-steam mixture being vented.  This is a known and anticipated process, but the amount of hydrogen gas produced was unknown because the operators didn’t know the exact temperature of the fuel rods or the water level. Since hydrogen gas is extremely combustible, when enough hydrogen gas is mixed with air, it reacts with oxygen. If there is enough hydrogen gas, it will react rapidly, producing an explosion. At some point during the venting process enough hydrogen gas built up inside the containment (there is no air in the containment), so when it was vented to the air an explosion occurred. The explosion took place outside of the containment, but inside and around the reactor building (which has no safety function).  Note that a subsequent and similar explosion occurred at the Unit 3 reactor. This explosion destroyed the top and some of the sides of the reactor building, but did not damage the containment structure or the pressure vessel. While this was not an anticipated event, it happened outside the containment and did not pose a risk to the plant’s safety structures.

Since some of the fuel rod cladding exceeded 1200 °C, some fuel damage occurred. The nuclear material itself was still intact, but the surrounding Zircaloy shell had started failing. At this time, some of the radioactive fission products (cesium, iodine, etc.) started to mix with the water and steam. It was reported that a small amount of cesium and iodine was measured in the steam that was released into the atmosphere.

Since the reactor’s cooling capability was limited, and the water inventory in the reactor was decreasing, engineers decided to inject sea water (mixed with boric acid – a neutron absorber) to ensure the rods remain covered with water.  Although the reactor had been shut down, boric acid is added as a conservative measure to ensure the reactor stays shut down.  Boric acid is also capable of trapping some of the remaining iodine in the water so that it cannot escape, however this trapping is not the primary function of the boric acid.

The water used in the cooling system is purified, demineralized water. The reason to use pure water is to limit the corrosion potential of the coolant water during normal operation. Injecting seawater will require more cleanup after the event, but provided cooling at the time.

This process decreased the temperature of the fuel rods to a non-damaging level. Because the reactor had been shut down a long time ago, the decay heat had decreased to a significantly lower level, so the pressure in the plant stabilized, and venting was no longer required.

***UPDATE – 3/14 8:15 pm EST***

Units 1 and 3 are currently in a stable condition according to TEPCO press releases, but the extent of the fuel damage is unknown.  That said, radiation levels at the Fukushima plant have fallen to 231 micro sieverts (23.1 millirem) as of 2:30 pm March 14th (local time).

***UPDATE – 3/14 10:55 pm EST***

The details about what happened at the Unit 2 reactor are still being determined.  The post on what is happening at the Unit 2 reactor contains more up-to-date information.  Radiation levels have increased, but to what level remains unknown.


  1. Interesting quote from Rod Adams:

    According to the writer and editor who approved th[is] summary, “An explosion at a nuclear power plant on Japan’s devastated coast … made leaking radiation, or even outright meltdown, the central threat menacing a nation.” Apparently aftershocks, fires, broken dams, washed out highways, lack of clean drinking water, damaged sewer systems, destroyed airports, and at least a thousand known fatalities are not as much of a threat to the nation of Japan as the possibility that a few people might be exposed to a radiation dose that is roughly equivalent to the ones administered every day as part of routine medical procedures.


  2. It could be pointed out that hospitals rely on backup diesel generators to keep essential equipment working. Thankfully they are not close to shorelines. I presume the reactors of this type that are not decommissioned will get better safety systems installed. I think we could overlook some extra emissions if the Japanese relied on gas for a few years. In 50 years we won’t have that option.

    So far the death toll from either radiation or explosions appears to be zero. You wouldn’t think so reading the Murdoch press which is hysterical.


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  4. I just received a response from an executive engineer in an international multidisciplinary consultancy. My close friend for over 40 years, he told me that he had no interest in reading my condensed version of events in Japan or why I consider nuclear power to be an attractive option for at least some of Australia’s future energy needs.

    It’s sad to find that he has already made up his mind, and that his answer is not to think.

    If his mind is closed, perhaps we shouldn’t be so hard on the journalists who think that their duty is to write what (they think) people want to hear. Nuclear power’s time will not come because people are bludgeoned with facts. It will come when the man in the street decides that nuclear is the way to go.

    The journalists will then follow their readers, always pretending that they are the leaders.

    So, by all means focus on journalists, but remember that public knowledge is what is ultimately needed.

    Dr Oehmen’s article is an excellent step along this path.


  5. Thank you for an easy to understand yet explanation of the event!

    I am wondering about this however:

    The intermediate radioactive materials (Cesium and Iodine) are also almost gone at this stage, because the Uranium decay was stopped a long time ago.

    Isn’t the half life of the radioactive Cesium something like 30 years? How can it be gone just a few days after the reactor shutdown?


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  7. Two questions, if I may:

    1. Why these reactors built along the east coast of Japan – ie facing the subduction zone – and not on the west coast?

    2. Will this reactor at Fukushima be able to go online again? If so, when?


  8. Good article, apart from the gratuitous innuendo about Iran “building a nuclear bomb”, a lame warmongering propaganda claim which has been demonstrated false long ago.

    If you really want information on the difficulties of building a nuclear arsenal, you’d better ask a nation which actually has one, like Israel, or USA.


  9. 1. East coast is near major load centres and transmission infrastructure. There are clearly questions about the preparedness of these plants for a tsunami, which will have to be looked at carefully for future planning.

    2. Unit #1 will be decommissioned – it was 40 years old anyway and was due to be shut down. Unit #3 will probably also be written off. Units #2 and #4 will probably be restarted, but not for quite some time, anywhere from 6 months to 3+ years.


  10. Thanks for this! I am not a supporter of nuclear reactors, but think of them as a necessary “evil” until we can devise safer ways to make energy. The recurrent thought running through my head while reading your article was “Thank God these are Japanese designed” since I truly respect the engineering of Japanese products.

    I hope that all plays out as you have described.


  11. Moderator rods exist in some types of reactor, but common PWRs and BWRs use light water flowing around the fuel bundles as both moderator and coolant.

    The rods that absorb neutrons are control rods, not moderator rods.

    A moderator is any material which moderates, slows down, neutrons.

    It is not a delicate balancing act to make sure the reactor stays precisely critical, in order that the reaction not quickly run away towards zero or towards infinity(until something breaks or explodes).

    Reactor are stable and manageable for several reasons. By stable I mean that the power output responds slowly and injection of a small amount of reactivity(e.g. partially withdrawing a control rod) will cause power to increase slightly before leveling off at a new, higher value without any operator intervention.

    There are delayed neutrons from some short-lived fission products. In a nuclear bomb only the prompt neutrons are needed to sustain a super-critical state, the rate of the reaction increases so quickly that an enormous amount of energy can be produced before the fissile core of the bomb blows itself apart. A reactor is not like a bomb; it’s not prompt critical; if it weren’t for these delayed neutrons the reaction would quickly die down(we’re talking miliseconds here) these delayed neutrons come from isotopes with half-lives of between a second and a minute. When you rely on delayed neutrons to maintain criticality the power level can’t change very rapidly; the reaction increases or decreases on time scales appropriate for human intervention.

    There is also a whole host of effects that tend to stabilize the power level. These can be anything from thermal expansion of moderator, thermal expansion of fuel pins, doppler broadening, chemical dissassociation(hyperion’s uranium hydride design) formation of voids in the coolant/moderator(e.g. the bubbles of steam in a boiling water reactor).

    The purpose of slowing down neutrons in a thermal reactor is that it increases the fission capture cross section for fissile U-235(and Pu-239 if present). You can build these reactors with small fissile inventories or very slight enrichment(or none, as in a CANDU).

    Reactors that slow neutrons down to such low energies that most of them are at a simular temperature as the reactor itself are called thermal reactors. Light water reactors are all thermal reactors.

    In a fast reactor the neutrons remain very fast because the core contains no good moderators(compounds of light elements with a large collision cross section and a small capture cross section, such as water, heavy water, carbon, beryllium and fluoride salts). The purpose of operating in the fast spectrum is that it enables breeding with the plutonium fuel cycle; although the fission cross section is smaller(necessitating more fissile inventory; about 10 metric tonnes per GW), the capture cross section of fission products is reduced even faster, reducing parasitic losses and thereby improving the neutron economy.

    Thorium reactors can breed in the thermal spectrum given some online removal of fission products as in the molten salt reactors.

    The moderator can also play an important role in making a reactor stable or unstable against increases in temperature or formation of voids(of steam, typically).

    In reactors with light water as coolant/moderator the effect of partially withdrawing a control rod is to inject a certain amount of reactivity; neutrons multiply and power increases. But this is self-limiting; as water heats up, its expands, becoming less dense and a poorer moderator.

    In a light water reactor the formation of bubbles of steam reduce moderation, causing the reaction to die down.

    In RBMK reactors they used both graphite and light water as moderator; graphite is better moderator, so bubbles of steam in the core would tend to increase moderation, not reduce it. In an RBMK the void coefficient is strongly positive, this means that if ever the water in the core were to begin to boil the reactivity would increase, causing power to increase, causing more water to boil and increasing reactivity further in a vicious circle; this run-away reaction happened at chernobyl and the control rods took too long to be inserted stop it in time before the steam explosion.

    [Ed: Thanks for picking that up Solyent, I missed it in my rapid read through. Have updated]


  12. Good write up. Only thing I would say different is that the Reactor Building is designed to maintain a negative pressure relative to the outside atmosphere to prevent the spread of radioactive contamination. Its ventilation exhaust is monitored for Radiation/ Contamination and isolates if sensed. This is the standard GE BWR design and called “secondary containment”.

    Part of that purpose is to also address a fuel handling event on the Refueling floor. Unfortunately the spent fuel pool and the Refueling floor area is where the walls were lost during the hydrogen explosion.

    That is the top area of the Reactor Building image which shows the crane used for vessel disassembly in the overhead. These walls are not as robust as the balance of the Reactor Building walls which would explain why they failed first.

    No real word on that status, but current Radiation levels seem to imply adequate water level remains in the Spent Fuel Pool. The actual pool is steel lined and concrete walled.


  13. The most significant problem is not going to be power shortage, but finding the funds to decommission the wrecked reactors. This will cost far more than it did to construct them in the first place.

    Presumably TEPCO will declare itself insolvent and leave the next few generations of the Japanese public paying for it.


  14. The author seems to have missed the vertical shock wave just before the outer walls were torn apart. IMHO the hydrogen explosion took place within the third containment and blew away the concrete shield plug (vertical shock wave).


  15. @ esquilax

    Actually it is no and yes.

    Regarding the first question, this is what the Japanese experts came up with :
    The 500 years event was a 8.6 magnitude quake. The present earthquake was 5 times more powerful !
    Hindsight bias anyone ?

    Regarding the second question, here is one solution : http://en.dcnsgroup.com/energie/civil-nuclear-engineering/flexblue although there is a good chance that a “simple” EPR, with its air-tight and water tight redundant ECCS would have stood the tsunami test.


  16. Thank you for a clear, well-supported summary of the likely events at Fukushima. We’re in Tokyo and are fairly stressed about the ongoing crisis. I’d be grateful if you could confirm whether the summary you’ve provided can be applied all the reactors at the Fukushima site. Evidently, a number are affected.

    Really helpful. I’m a big fan of nuclear energy and can’t frankly understand why folks in the US are so frightened of it. The part about the plugs not fitting sent chills up my spine. Beyond that, the lessons of Fukushima seem to be: build better protection for cooling systems, back-up the back-up, and ensure the plugs match. Things not to do? Continue to rely on obsolete systems or curl into the fetal position.



  17. Wonderful explanation, thank you! I have just one remaining question: if the worst-case scenario brought the core catcher into play — where does the SNF end up? Is that storage pool completely separate & does it remain intact? Or could we have a LOCA up there?

    Thanks again for your insights!


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  19. Bravo, Barry! A very useful post.

    The details will keep on coming for a long time — but your estimates and predictions are right on target. The BWR experts in the US are bringing in their materials regularly, now. The disaster speculators will be disappointed — the crisis is about over now.



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  21. em: is it certain that this plant had negative pressure?

    and what exactly was negatively pressurized? the containment (third)?

    Barry: great job. Wolf Blitzer of CNN could not get the word “Chernobyl” out of his mouth enough.

    the japanese ambassador never corrected him.


  22. @ charles

    The operator (TEPCO) is blaming the tsunami which was/is completely foreseeable, given the site is on the coast (duh!). Which one do the apologists want?

    BTW, earth quake magnitude and the size of (any) tsunami wave are not always correlated.


  23. “the crisis is about over now”

    The BBC just reported a State Of Nuclear Emergency for Onagana NPP, confirmed by the UN/IAEA because of “excessive radiation levels”.


    “(The) water level gauge in Fukushima nuclear reactor 3 may have failed – ‘We don’t know what’s going on’, says chief cabinet secretary.”


  24. Thank you! I have been pulling my hair out over the garbage the media has been incorrectly and dangerously spewing to the public. It is at relief to find an article that accurately describes the accident, written in a manner that most people should understand. Again, thanks!


  25. Well written, but some references to support your claims would go a long way. Particularly on points regarding the specific construction of THIS reactor and its rated specifications. You’re certainly correct on many points but, without references, you only appear as authoritative as the inaccurate media you are chastising.

    Also, the difference between 8.2 and 8.9 on the Richter scale is 10^0.7, which is 5, not 7 (the Richter scale is base 10 logarithmic).


  26. Some easily verifiable objective facts: (not from a ‘scientist’ working for the nuclear lobby)

    “Chief Cabinet Secretary Yukio Edano said an explosion could take place in the building housing the No. 3 reactor at the Fukushima Daiichi plant in northeastern Japan.

    “There is a possibility that the third reactor may have hydrogen gas that is accumulating in the reactor (that) may potentially cause an explosion,” he said.

    An explosion caused by hydrogen buildup Saturday blew the roof off a concrete building housing the plant’s No. 1 reactor, but the reactor and its containment system were not damaged in the explosion.

    Edano said the No. 3 reactor would also likely withstand a similar blast, noting that workers had already released gas from the building to try to prevent an explosion.

    Hydrogen means at least partial core’s meltdown.

    MOX very dangerous nuclear fuel is used at the No. 3 Daiichi reactor, maybe at the No. 2 also.

    Zirconium liner fuel is only used in Kashiwazaki-6 and 7 (ABWR 1350MW), not in BWR (500MW or 800MW) plant design of Fukushima Daiichi and Onagawa.

    Japanese Nuclear Reactors have a strong design, that’s true, but they have to resist to several small/medium earthquake/year.

    Since 11 march, they took level 9 earthquake (designed for max level 7) + tsunami 2-10meters wave + many replica level 5 and more.

    These reactors aren’t designed to be cooled by sea water.

    No. 1 reactor Fukushima Daiichi is 40+ year old.

    At least 69 officially irradiated persons.

    Last news say :

    1. water level don’t increase in reactor No1 2 and 3, sea water don’t work, they don’t understand why

    2. Japanese authorities have informed the IAEA that the first, or lowest, state of emergency at the Onagawa nuclear power plant has been reported by Tohoku Electric Power Company + Onagawa had an fire emergency at 11 march.

    Japanese people need support and real infos, i really hope things will go better.


  27. Kaj, there might be some slightly different effects on the void reactivity coefficient and stuff like that because the fission cross section for Pu as a function of the neutron energy is different than U-235.

    And of course there’s plutonium phobia to contend with with the MOX fuel, irrespective of the real science and engineering information.

    Anyway… in the GE BWR-3 like Fukushima I Unit 1… if there is excessive pressure within the primary containment vessel, where will it be vented to? Will it be vented out into the reactor building, outside the inner containment structure?

    What about venting excessive pressure from the torus? Will that be vented out into the reactor building?

    I’m trying to better understand the path of the hydrogen from within the torus into the area on top of the reactor building, where the fuel transfer crane is, where the steel walls were blown out by the explosion.

    The outermost layer of the multiple layers of containment – the reactor building – has walls and a roof made of solid concrete, and it’s roughly cube-shaped.

    On top of the concrete reactor building, however, there is an additional part of the structure – it is not made of concrete, but it is made of steel, with steel sheets over a steel frame. Refer to the drawings posted previously above.

    This steel building on top of the reactor building houses the fuel transfer crane, and it is built on top of the concrete roof of the reactor building. I’m referring to the part of the structure above the concrete shield plug and the refueling platform at the top of the concrete reactor building.

    It is this relatively weak steel structure on top of the concrete reactor building, which is not really part of the reactor building proper, which seems to have been blown out by a hydrogen explosion.

    The explosion does not appear to have occurred within nor does it appear to have breached any of the fundamental layers of containment structure.

    It appears that the building has been breached as a result of a hydrogen explosion. It’s probable that excessive hydrogen generation within the reactor core, either radiolytically or chemically by reduction of water in the presence of the zirconium cladding at significantly elevated temperatures, has been vented into the torus, and as temperatures and pressures have began to rise within the torus steam pressure in the torus has been vented out into the reactor building surrounding the torus.

    From there, the hydrogen mixed with that steam and water vapor has risen, as hydrogen does, and worked its way through the reactor building, escaping at the top of the reactor building, and accumulating at the top, in the area around the fuel transfer crane. It then appears that the accumulated hydrogen has mixed with air and exploded.


  28. Cristina,

    Regarding the used fuel storage pool, it is not in the reactor building, as far as I’m aware. It’s a separate building, which is designed to be very robust and seismically hardened as well.

    There is a very small pool in the reactor building near the top of the reactor vessel which is used to temporarily hold the used fuel during its unloading from the reactor.


  29. “The Zircaloy casing is the first containment.”

    ** Not Correct **

    1st containment is the ceramic fuel pellet itself. The fission process produces fission fragments, or radionuclides, which almost entirely remain within the ceramic fuel pellets. Only a very small fraction of fission fragments escape the fuel pellet, unless the pelet integrity is comprimised by melting or some other degredation.

    The 2nd barrier is the zircalloy tube; 3rd – primary coolant system; and so on…

    This is not quibbling, but rather an important and fundemental reactor design safety feature.


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  31. Hmmm. The plugs on trucked in temporary diesel generators did not fit? Did anyone in Japan ever heard of temporary connection rigging. Or is the status quo in Japan entrenched like here in US where electrical inspectors will threaten you with multi million dollar fine if you don’t comply with polished electrical code so the guys who try to help in emergency will spit in disgust and walk away? 8 hours is very long time in which temporary electric power should be connected by any means or batteries should be charged with temporary hook-up to prolong the time. Most electrical engineers will be scratching their heads why this was not done in 8 hours time.
    This accident in Japan is another classical case how mother nature wins when she is allowed to run her natural course. Add to it the human status quo and you have a screw up of first magnitude.
    I am sure after the investigation is done a lot of heads will be rolling. I would not be surprised if some individuals commit hara kiri.
    Nevertheless, after the fact solutions are no consolation to reactor owners who face massive financial losses for clean up and overall further damage to nuclear industry that anti nuclear elements will surely exploit.
    This is why only three weeks ago I was pointing to unbeatable natural safety features of Molten Salt Reactors as a preferred method to generate nuclear power.
    One thing is certain, this accident will not play well for IFR acceptance.


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  33. Frank: An old Naval invocation: “Point the Guns Outboard, Lads!!”

    Personally, I cannot understand people who take advantage of any opportunity to further their own limited objectives, even in the midst of a most difficult situation such as exists in Japan.

    The next time a 10 meter wave washes over a nuclear power plant of any particular design, I hope all of us will take a moment to recognize that the situation on the ground is somewhat less than ideal.

    I think the Japanese are doing rather well in controlling this 40-year-old reactor, which was scheduled for final shutdown a couple of months from now.


  34. I can hardly imagine what people, who work in the nuclear station, are surviving right now. I believe that they are aware of how big responsibility is laying on their shoulders. It´s too late and too early to blame somebody, it has already happened. The major task is to save as many lives as possible.


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  36. A very interesting post and great to know given that many friends are still living in Japan – the place I called home for two years.

    However, ‘safe’ or not, I am still very much relieved that New Zealand, my home country, is Nuclear free – and long may it stay that way! Thank you David Lange for leaving us that!


  37. Excellent summary, thanks. A small point – it would have helped if the diagram had not labeled as primary and secondary containment what the text refers to as secondary and tertiary.

    I certainly hope your assessment of the situation at Fukushima plays out.


  38. Barry, thanks for the explanation.

    Just one note – we haven’t heard the last of this. Invariably governments & companies lie. Just think about the gulf drilling disaster.

    Next time someone compares costs with PV or Wind these scenarios should be included. Tax payers shouldn’t be the ones funding all these …


  39. Pingback: Cranky-D » Japan’s Nuke Plants

  40. This part of Japan is next to a subduction zone. Subduction zones are known for their ability to create magnitude 9+ earthquakes with large tsunamis, such as the 1960 Chile earthquake and the 1964 Alaska earthquake. It’s not rocket science to understand that nuclear plants in this kind of environment need to be designed and operated to handle seismic and tsunami events that are quite large.

    BTW, the Richter scale is no longer used much, but its most common replacement the moment-magnitude scale uses the same logarithmic scale, just with a different calibration.


  41. Comment on three areas:

    1 – the explosion in the reactor building.

    It obviously wasn’t hugely powerful – it seems to have removed cladding, but left the structural steelwork substantially undamaged.

    I can’t see an obvious pathway for hydrogen generated in the core to the into the building. Or at least, not one that wouldn’t have radioactive material coming along with it, and a substantially greater level of radioactivity.

    There is, however, another source of hydrogen on the plant – that’s the hydrogen coolant for turbine stators. There are some reports that the explosion originated in the turbine hall.

    2 – the overall impact. Dependent on the end outcome, it’s obviously not good for the pro-nuclear argument. But, there’s a counter-argument, and that’s “in an unforseeably bad combination of circumstances, a 40-year old plant not only survives the intitial fault, but is then managed to a succesful outcome, then how bad would it have to be to actually cause significant release?”

    3 – timing of any action. Just doing some basic sums, and I think the heat generation is probably down to under 10% of what it was immediately post-trip – perhaps 8MW versus 90+, and 1500 or so under full power.

    So far as I can see, researching online, it’s usual to open up a BWR RPV about 4-7 days into a refuelling shutdown – heat generation at that point, on a plant of Fukushima 1’s size is 7-8MW. Now, obviously, at that point, there’s no boiling, and unpressurised water circulation is enough to maintain cooling.

    Can anyone who knows BWRs reasonably well confirm that? My background is AGRs, rather than light water designs. It strikes me that at that point, we can reasonably assume all’s under control.


  42. . Invariably governments & companies lie.

    I wouldn’t go so far as invariably. But that’s a quibble.

    What’s more important is the direction in which they lie. Today Japan is full of power plants and fuel reservoirs that have been killing people. All the plants had been burning, and all the reservoirs contained, much more expensive fuels than the Fukushima plants, and the Japanese government is a major beneficiary of that expense.

    If it must lie, won’t it lie in the direction of favouring its fossil fuel income?


  43. Shame that this isn’t true

    “Some radiation was released when the pressure vessel was vented. All radioactive isotopes from the activated steam have gone (decayed). ”


    Japan’s nuclear safety agency said on Sunday there was no problem with the cooling process at Tohoku Electric Power Co’s (9506.T) Onagawa nuclear power plant and that a rise in radiation levels there was due to radiation leakage at another plant in a neighbouring prefecture.

    100Km away the leaked radioactivity is being detected


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  46. It is time for everyone to look at facts, not emotionally respond, nor ignore the realities of living on the Earth. The recent article in the Times Magazine published yesterday, http://ecocentric.blogs.time.com/2011/03/12/japans-radiation-exposure-how-serious-is-it , demonstrates how poor research, bad writing, and incomplete and or incorrect facts can skew and misinform the reader.
    The article suggests a doomsday is approaching, and that the slightest amount of pollution of various materials involved in the nuclear process will be fatal to the existence on Earth. Let us examine the facts.
    One common email this past week shows the proliferation of 3000 RADS of Nuclear fallout to the Aleutian Islands in three days, 1500 RADS of Nuclear fallout to the coast of Canada in six days, and 750 RADS of Nuclear fallout to Nebraska and Nortyh Central Mexico in ten days. Pollution would travel in the upper atmosphere if it were to spread, and exposure would only be probably caused by particulates from dust or attachment to rain. So far, there is not a dust cloud from the nuclear plants. There is probably small amounts of steam. The liklihood of exposure over more than a few miles is improbable.
    The fact is the “Nuclear Fallout Map” is a hoax based on jet stream maps and little additional facts. See further http://bhalomanush.posterous.com/my-take-on-the-japanese-nuclear-fallout-map-h . A “RAD” is a term associated with radiation and nuclear fallout. It refers to exposure, but is not meaningful in itself. (The rad is a unit of absorbed radiation dose. The rad was first proposed in 1918 as “that quantity of X rays which when absorbed will cause the destruction of the [malignant mammalian] cells in question…”[1] It was defined in CGS units in 1953 as the dose causing 100 ergs of energy to be absorbed by one gram of matter. It was restated in SI units in 1970 as the dose causing 0.01 joule of energy to be absorbed per kilogram of matter. The United States Nuclear Regulatory Commission requires the use of the units curie, rad and rem as part of the Code of Federal Regulations 10CFR20.) http://en.wikipedia.org/wiki/Rad_(unit) Rem is more likely to be used. (The röntgen (roentgen) equivalent in man (or mammal[1]) or rem (symbol rem) is a unit of radiation dose equivalent. It is the product of the absorbed dose in rads and a weighting factor, WR, which accounts for the effectiveness of the radiation to cause biological damage.) http://en.wikipedia.org/wiki/R%C3%B6ntgen_equivalent_man .
    So what is sieverts? “The sievert (symbol: Sv) is the SI derived unit of dose equivalent. It attempts to reflect the biological effects of radiation as opposed to the physical aspects, which are characterised by the absorbed dose, measured in gray. It is named after Rolf Sievert, a Swedish medical physicist famous for work on radiation dosage measurement and research into the biological effects of radiation.” http://en.wikipedia.org/wiki/Sievert.
    Now, given the definitions, a better understanding of nuclear fallout is appropriate. Is it in the atmosphere or will it be on the ground? If it exists, it will start at very high altitudes with the jet stream. Will it reach the ground? Possibly if there is enough up there. Are the Japanese reactors emitting significant amounts of nuclear waste? Probably not. There are layers of containment. A melt down is the destruction of the fuel rods, but a meltdown is a possibility considered in the construction of nuclear facilities. The probable consequence is that local people will be evacuated for safety after the experience with a far less safe nuclear facility, Chernobyl. Additionally, as a society, we should watch for safety flaws, but not over react.
    A more serious problem to Earthlings is the rate we are using up natural resources and not replenishing them, the pollution of fresh and salt water, the pollution of the upper atmosphere, and the rapid population explosion that may make the Earth uninhabitable within 500 years.
    [This article is published in Time Magazine comments this week.] http://ecocentric.blogs.time.com/2011/03/12/japans-radiation-exposure-how-serious-is-it


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  48. How can you be sure that in the case of a full meltdown, the nuclear fuel wont melt through the steel and concrete containment vessel? Ive heard the steel there is only 6” thick, whereas newer reactors are much thicker?


  49. As a former NRC licensed operator of a BWR, the write-up was spot on (minor quibbles with some terms). How would anybody fare is every back-up failed when it was called on?

    It has been suggested that the designers failed to consider an earthquake of sufficient magnitude (design 8.2 vs. actual 8.9). My question to those would be this: what would be a a good enough design earthquake? Magnitude 10? 11? Nothing could be built economically if that is your criteria. That is pure wishful fantasy.

    It is possible to economically design something to withstand foreseeable casualties. It is possible to design something to withstand every possible casualty, foreseeable or not. It is not possible to economically do both.


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  51. “The small amounts of Cesium that were measured told the operators that the first containment on one of the rods somewhere was about to give.” – Que? Surely this would indicate that the casing was broke, not about to break?

    ” I am not quite sure if they flooded our pressure cooker with it (the second containment), or if they flooded the third containment, immersing the pressure cooker. But that is not relevant for us.” –
    Umm… flooding a nuclear reactor with sea water kinda seems desperate to a non-specialist like me.

    Also it’s not over yet. But, thank you for staying calm however.

    Also what’s the fatality rate for petrochemical power vs nuclear? I’m guessing oil kills more…


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  53. I know some people at Australian Radiation Services – the Melbourne-based health physics and radiation safety firm whose logo appears on that extremely dodgy looking plume map.

    I do not think they would really turn out crap science. They’re serious professionals in a serious field, and they know what they’re doing. I’m seriously tempted to flick them an email to confirm whether or not their organisation did actually produce that chart or if someone else has mendaciously put their name on it.


  54. Thank you. From someone familiar with BWRs, this is a nice synopsis. Agree that we should be celebrating the engineers who had the forethought to have multiple cooling systems, multiple layers of containment, backup generators and batteries, and, when many of these failed, yet another backup in the seawater. Let us continue to give the situation the attention needed to maintain containment integrity while we focus on the immediate needs of thousands stranded without food or water.


  55. While the radioactive Cs and I isotopes are obviously important and a primary focus in nuclear incidents of the type that is occurring at these plants, I think that it is counterproductive (ultimately, in the same way that all the more egregious media misinformation is counterproductive) to frame the discussion as though those are the ONLY two fission product radioisotopes that have been and will be released. As a minimum an informed perspective requires an understanding of why the other radioisotopes of the fission product yield (e.g., http://en.wikipedia.org/wiki/Fission_product_yield#References) are of less significance in this incident.


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  57. “A Japanese official said 22 people have been confirmed to have suffered radiation contamination”

    This contradicts your claim that “If you were sitting on top of the plants’ chimney when they were venting, you should probably give up smoking to return to your former life expectancy. The Cesium and Iodine isotopes were carried out to the sea and will never be seen again.”

    Or perhaps you are suggesting that 22 people were sitting on the chimney?

    Just because the operators are trained for these events, that does not mean they are not serious events.

    I don’t think I’ve seen any media reports anywhere that claimed that the chain reaction had not been stopped or some other catastrophic situation remained. You do not need to debunk non-existent stories. The media has done a good job.

    However, you have written a good summary.


  58. Thank you Mr Brooks. That was excellent. I would like to think that our news media is just ignorant and trying to catch up to reality. Howver, they surely had experts to call upon that gave this information to them within hours. That means they’ve just been hyping things with their talk of meltdown etc for ratings. That’s not surprising, but no less disgusting! Thank you for the truth!


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  60. It very helpful read the account provided here. As a retired nuclear professional, I learned specifics about the plant and the sequence of events that I did not see elsewhere. I came across this account via a citation on Real Clear Politics, so hopefully the article will receive additional attention.

    I do have a comment to an assertion by esquilax that it is not possible to design around the problems experienced by the Fukushima plants. In 20-20 hindsight, design solution is clear. The diesel generators for backup power should be in an enclosure protected from the effects of a tsunami (as the reactor itself is).

    It is reassuring to learn that despite encountering an earthquake five times as severe as the design basis earthquake (which itself is twice as severe as the worst earthquake ever to hit Japan previously), the plants withstood the earthquake.

    Let us hope that the scenario does play out as forecast in the article (i.e no new unpleasant surprises) and that the worst is over.


  61. I don’t think a meltdown from loss of coolant in a water reactor is the same thing as a chain reaction. At chernobyl, loss of coolant increased the rate of fission due to the particulars of the graphite moderator. That was a chain reaction.


  62. Very nice summary. I am a health physicist but with no NPP experience. If you update the information here I would find this helpful: (1) regarding the facility design: where are the operators located and what protects them? (2) What is the design and location of the coolant piping systems – they apparently are robust enough to have survived the explosion but still must somehow not be completely inside the protected structures if seawater can be brought in. And (3) NISA reports 40 microSv/h (4 mrem/h for US readers) measured at the site boundary – would this have been a short term measurement while noble gases were being vented, and if not what would explain that?


  63. The Fukishima nuclear reactors are Boiling Water Reactors, BWRs. So they were designed and built by the GE-led, BWR reactor consortium.

    It is reassuring to note that the new American “Standard Design ” reactors, so painstakingly being designed, reviewed, modified and certified, ALREADY INCLUDE extra provisions for the remote set of circumstances that affected one of the 53 nuclear reactors in Japan forced by the Japanese Earthquake and subsequent tsunami.

    New American “Standard Designs” are re-designed so that they have no problems if commercial power is unavailable; and All not just some of the emergency diesel generators did not start.

    The new “Standard Designs” nearing final approval, after almost five exhaustive years, of analsysis, modification, and approval and final certification of every nut and bolt in the design. They were redesigned to not need the power for the pumps, at all. These new “Standard Designs” rely on placing the coolant tank above the reactors and letting the emergency cooling water flow down into the reactor vessel by gravity, without needing any pumps. Secondly, they have been redesigned so that the coolant capacity is much larger inside the reactor vessel, requiring less from outside to be added.

    Third, the larger coolant capacity reactors are not so time critical to a meltdown. They extend the time to a meltdown without cooling to several hours instead of 45 minutes, allowing more time to thoughtfully react.

    Fourth, they have been redesigned so that natural thermal convection will circulate the coolant water, inside the reactor, thus eliminating the need for power to the pumps, or the pumps at all.

    Isn’t it further proof that the new reactors and the new NRC certification scheme of “Standard Design”, makes much more sense. It used to be that letting progress occur by each new plant be a single design, perhaps incorporating new features unique to itself, and much more anticipatory rather than reviews while under construction, or in post-accident design fixes.


  64. As to the question how the hydrogen ended up in the reactor building, my (layman) understanding that it first formed inside the reactor vessel and entered the suppression pool system via approaches to cool the reactor (RCIC/HPCI). As suppression pool temperature increased, pressure was released into the containment. After pressure in the containment subsequently reached a critical state, containment was vented – leading to hydrogen mixing with oxygen in the reactor building.

    I may of course be totally off. Based on:


    Click to access 03.pdf


  65. Reading the Fukushima thread at The Oil Drum I see many assert that we must replace nuclear with wind and solar. Fair enough but how are we going to also replace coal, oil and gas?

    There has been a fatality with the death of a crane operator at the Daini group of reactors.


  66. The main thing that needs to happen if or when they overhaul the reactor plants in Japan, is to move the darn things on the WEST coasts, OPPOSITE of the eastern coasts of the Japanese islands that are in the direct line of exposure to major seismic and tsunamic activity……while no place on earth is completely invulnerable to natural disasters, there are some places that are statistically better than others…..


  67. Wait a minute, has this website not been championing a new generation of nuclear technology (Gen IV) that would largely eliminate most of the multifarious risks that have been associated with traditional nuclear reactors?

    If so, does this incident not add weight to the case that the new technology ought to be pursued when building any new nuclear plant?

    And if so, should this incident not be viewed as a positive, prescient signal to the world that other technology may soon be available – if not already – and to immediately forsake investments in nuclear plant using older technology?

    If Brave New Climate is really certain about its prognostications re the new safer technology, then it should have nothing to fear from this incident. It presents a golden opportunity to put its case for a technology transition, surely?


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  69. I have engineered six BWRs, Mark I, Mark II, and Mark III containments. This is an early Mark I. I would quibble with some statements but consider this article infinitely better than the errors, both ignorant, and intentional, that have been reported. Japan is not out of the woods yet, but we must acknowledge the skill and courage of their people, particularly those working the emergency. There are a lot of unknowns but this report, and time, indicates the good guys are winning, regaining total control, perhaps at the cost of a modest number of deaths, a statement which may have no scale of meaning.
    There will be time for informed assessment, and perhaps malfeasance confronted, but now is the time for prayers and best wishes, to a grievously suffering nation.
    IMHO, the next unknown to fear is another probably great quake, an aftershock, and possible tsunami over the next week.


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  71. Good post – thank you.

    However I have to comment that the attempt to downplay the radiation risk is misguided and will do the nuclear cause no good.

    You say:-
    By “significant” I mean a level of radiation of more than what you would receive on – say – a long distance flight, or drinking a glass of beer that comes from certain areas with high levels of natural background radiation.
    However Tepco (the operator) say
    “The radiation exposure of 1 TEPCO employee, who was working inside the reactor building, exceeded 100mSv and was transported to the hospital.

    Slightly more than you get from a glass of beer, especially as they do the “more than” bullshit.

    The 40 year old plant took extraordinary damage and did most of its job, but the general opinion will further harden against nuclear – folk just don’t like even a tiny chance of great risk.

    Given that Spain’s electricity is 35% renewables and Portugal 45% I know where I would put Australia’s money. Build wind and solar as fast as possible and plan a few nuclear installations but don’t start for 10 years. By the time you are ready to build we will know how the renewables are doing.


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  73. barry: in that video, while you speak, the picture shows arrows pointing out of the nuclear plant with the words “cancer and genetic defects” underneath.


    In an earlier video, you mentioned that newer plants had no problems. could you elaborate? what sort of plants were these to which you refer?


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  75. Greg, plants like the AP1000 have passive cooling systems that work by convection and gravity feed, so don’t depend on external power. Plants like EPR have fully isolated and sealed power units for the ECCS so would have not been damaged by the tsunami. Sorry for the short reply, being overwhelmed by media stuff right now.


  76. Much better analysis than the TV but Mr. Brooks curiously congratulates Japanese construction because the facility withstood more than the 8.4 or so that it was designed to take (failing then to criticize the forecasters). But the 9.0 earthquake was centered a couple of hundred miles away, so what was the intensity at Fukushima? I’d think it would be below the design limit. More to the point, what would have happened if the 9.0 earthquake had occurred closer to Fukushima, or if several large tremors had occurred back to back and the control rods or the battery somehow was disturbed?


  77. We all love to read something that confirms our opinions. Most people here seem quick to condemn any report that does not support the view that everything is fine, and then just to praise a report from an “MIT Research Scientist” . [ad hom deleted] I will take this report along with all the others claiming there is likely to be a big release of radioactivity with a huge grain of salt until this is all over in a few weeks/months time.


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  79. Excellent, informative article.

    Interesting perspective from Sonya terBorg, above about how great it is to be safe in a “nuclear free” New Zealand, given that 29 coal miners were recently killed in NZ’s Pike River coal mine disaster, providing non nuclear fuel. So just how many people have been killed in Japan’s nuclear industry?

    For some people, fantasy will always triumph over reality.


  80. Bill Brown, hard to say at such energy levels, but it was telling that the critical damage was done by the tsunami, knocking out all of the backup generators and redundant generators in one fell swoop. The earthquake itself simply caused a SCRAM and doesn’t seem to have damaged the reactors, which have some degree of seismic isolation. So an ocean-based incident may have made matters worse. But the time for such analysis will have to wait, too much speculation at this stage.


  81. I am still confused about the sea water injection. First of all, did they flood containment or only injected into the reactor vessel? Wouldn’t flooding the containment have implications if a core meltdown can not be averted by injecting into the vessel (hydrogen/steam)? Also where exaclty does the assertion that “core meltdown has been averted” made in the post stem from? Are we there yet?

    Meanwhile, NHK reports that Tepco has informed the government radiation is again above legal limits at Daichi 1, but doesn’t understand what is causing this .


  82. disdaniel
    “If the nuke plants are so bloody safe, then why is half the world on the edge of its seat, praying that nobody (else) dies as a result of “unplanned failures” at Fukushima?”
    Why? because the media love to terrify the misinformed public by overstating any perceived problems with nuclear power. Most of the Australian press have been feeding misinformation to the general public BECAUSE IT SELLS PAPERS AND BOOSTS RATINGS. Thank goodness for a rational explanation such as we have been supplied with on this blog. BTW who has died (from radiation – unfortunately someone has been killed by a crushing accident) as a result of the current situation at the power plants? Meanwhile thousands have been killed by the earthquake and tsunami and more in fires which have broken out in oil and gas plants. Let’s get some rational perspective shall we!


  83. “If the nuke plants are so bloody safe, then why is half the world on the edge of its seat, praying that nobody (else) dies as a result of “unplanned failures” at Fukushima?”

    Because the media is churning this into a story when in fact there is really nothing there. There is much more damage in that country that is likely to impact more people that these reactors, but anything nuclear gets the fear factor higher than the possibly that an whole town has been swallowed up, which indeed might be the case.


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  85. disdaniel, people’s fears do not always correspond to reality. And while 4 people have been injured – last I heard – due to the various equipment failures and the explosion at Fukushima, the only fatality, of a crane operator, can reasonably be ascribed to the earthquake rather than the nuclear plant. Especially in the light of the huge numbers of casualties elsewhere which were also due tot he earthquake, and will not be ascribed to inadequate building or poor road protection or failed moorings or a million other possible but faulty causes.


  86. Thank you for an excellent piece, Professor Brook. The news sources here in the States (CNN, ABC News, etc.) have been nothing short of frightening when reporting on this story, repeating the same video loop of the explosion over and over along with the dramatic music and blaring headlines. They’ve all but shouted “We’re all gonna die!” to we the viewers and it really is quite upsetting. It is both refreshing and comforting to read something that takes a more level-headed, non-sensationalist, education slant to what is going on right now at these plants.


  87. The name ‘Chernobyl’ is sure getting a run in the world’s media at the moment. It would be good to see a clear analysis of why these reactors have not catastrophically failed in a similar fashion.

    Excellent blog and website Barry, and a great antidote to the [ad hom deleted] greens who both want to adhere to the science of AGW but at the same time distort the facts and science of nuclear power [deleted ad hom]


  88. Hi,

    Thanks for the great explanation. You said the plant is safe now and it will be safe, so, why I read a few minutes ago that the radiactivity is increasing again? So what happens if they do nothing now?


  89. RE; R.Hails comment

    I too examined the design of the containment building for Mark II and Mark III. Mark II is a little less sturdy than Mark III, but adequate for the design parameters set 40 years ago. Any engineering system needs to be upgraded as factual information becomes available. That is why we have Mark I, II and III. The present hysteria by the media does help our understanding of BWR systems, but only detracts.


  90. This is very good, but there is a correction required to the seismology bit. “As with the Richter scale, an increase of one step on this [moment magnitude] logarithmic scale corresponds to a 101.5 ≈ 32 times increase in the amount of energy released, …” from
    so an increase from magnitude 8.2 to magnitude 8.9 is over 20 times as much strain energy relased as the presumed design basis magnitude of 8.2.

    However, this still does not give the accelarations at the reactors compared to the design basis, since the distance from the earthquake epicenter matters greatly.


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  95. Correcting a numerical error in my comment of 14 March 2011 at 10:30 AM, the increase in moment magnitude of 0.7 means 11.3 times as much energy was released as in the design basis. If the earthquake were actually moment magnitude 9.0 [as seems likely], then the increase in moment magnitude of 0.8 means 16 times as muich energy.

    Nonetheless, until the distance from epicenter is figured in, these calculations say little about the accelerations experienced by the nuclear power plants versus the design basis accelerations.


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  100. This “feel good” post reminds me of the self-proclaimed petroleum expert who was putting out information during BP’s Gulf of Mexico rig disaster. He claimed it was only releasing a thin sheen of easily dispersible oil, and only in small quantity. We’ll know in a few days or weeks if this is yet more agenda-driven disinformation.

    Let us revolt. The power industry is a huge, self-serving and entrenched model. Equivalent investment in point-of-use generation/energy efficiency/conservation solutions would substantially reduce the need for costly overbuilding of peaking capacity.


  101. “My question to those would be this: what would be a a good enough design earthquake? Magnitude 10? 11? Nothing could be built economically if that is your criteria. That is pure wishful fantasy.”

    Jeff in Iowa, that’s a straw man. No one here has suggested any such thing.

    That said, the degree of earthquake and tsunami danger at the site may not have been adequately understood at the time that the first few units were designed and constructed. Nevertheless, the plant owner has had decades to study and reconsider these hazards in light of new geologic knowledge, and in response make appropriate adjustments to such things as emergency power supplies.

    I stand by my previous post.


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  103. Barry, you’re wrong.

    There will be a significant release of radioactive isotopes.

    Cesium has already been detected outside the reactor, and radiation levels are going up again for unknown reasons; fuel rods from the storage pools may have been blown into the air and dumped randomly on site.

    Reactor #3 is not effectively cooled even with the seawater being added. We’ll see whether it explodes and whether the containment vessel works. Radioactive gases have to be vented repeatedly to prevent the containment vessel from failing due to excessive pressure, so either it blows up or stuff is dumped in the air nearby — the hope is that the gasses can be scrubbed before being vented, but who knows?

    An informed public is essential to rejecting the chimera of nuclear fission steam engine plants in favor of renewables, which involve much less in the way of toxicity and are frankly cheaper per kilowatt-hour anyway.


  104. Barry, you’re wrong.

    There will be a significant release of radioactive isotopes.

    Cesium has already been detected outside the reactor, and radiation levels are going up again for unknown reasons; fuel rods from the storage pools may have been blown into the air and dumped randomly on site.

    Reactor #3 is not effectively cooled even with the seawater being added. We’ll see whether it explodes and whether the containment vessel works. Radioactive gases have to be vented repeatedly to prevent the containment vessel from failing due to excessive pressure, so either it blows up or stuff is dumped in the air nearby — the hope is that the gasses can be scrubbed before being vented, but who knows?

    All information from the IAEA.

    An informed public is essential to rejecting the chimera of nuclear fission steam engine plants in favor of renewables, which involve much less in the way of toxicity and are frankly cheaper per kilowatt-hour anyway.
    [ad hom deleted]


  105. Thanks fot the information.

    I stopped watching news channels when they showed the Tsunami originating just above Fiji (obviously closer to the US).

    I wish there was a short version. Then more people would read it.

    Thanks again.


  106. Outstanding work, and highly reassuring.

    It would be very helpful for lay readers like me if you might offer easily understood radiation exposure comparisons.

    e.g – as a result of radionuclide emissions, persons within 1km of the reactor received exposure equivalent to a n hours airline flight at 35,000 ft.


  107. Why were the back-up gen sets located in an area that could flood? Should they have not been located high up or in a sealed area.? What did the think would happen after a big quake? A BIG wave perhaps? Sounds like a flaw to me!


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  111. Hi Barry. What does “design basis accident” mean? I think who ever designed the back-up systems should be held accountable for such a common sence mistake. (Bechtel, Parsons, B&R perhaps?) Nuke is the future and this just about killed it!


  112. I’m in Japan and asked earlier if the analysis of the problems at Fukushima apply to just one reactor or to all the reactors at the facility. Perhaps, I missed the reply.

    It would be extremely helpful to have a frank assessment of the risks of each individual reactor, if possible. I’m persuaded that the particular reactor in question is in no danger of exploding. I’m not all convinced that the threats from the other reactors have been explained clearly, at least here.

    I appreciate the effort made here and remain pro-nuclear. Facts about the risks we face from other reactors are essential. Looking forward to an informed, well-supported update.



  113. It is unclear to me why control room levels of radiation are so high. They are ~ 1000 mSv according to most reports. The US Air Force and Navy are now reporting radiation in an airstream in the Pacific Ocean near the accident. The NYTimes reports releases will continue for many months. Finally, I am a geneticist, not a physicist, and I am aware that many workers (~160 by most current counts) have been significantly exposed. My profession became expert at judging the effects of Radiation on people only after Hiroshima and Nagasaki. Jim Neel (James V. Neel), now deceased, whom I knew, went to Japan to assess the effects of radiation several times after the war and eventually wrote a report for the UN about it. That report did not make these kinds of situations appear very safe. The long term consequences of radiation exposure are not pretty. Herman Mueller got a Nobel Prize in great part because he noted that radiation shows zero-order kinetics in its ability to cause mutation. No dose is low enough so that it is completely safe.

    I’m sorry the plugs didn’t fit.


  114. Good overview.
    Some comments:
    1. Metals which make up the primary loop piping, valves etc. can contain metals (such as Cobalt) which is often used as an alloy metal to control corrosion, and does have a more significant halflife than seconds (about 5 years). These particles can become entrained in a steam rupture etc, and pose a ingestion risk.
    2. Iodine is often cited due to the fact it is a very abundant fission byproduct and that it is particular nasty because the human body likes to use it in the thyroid. If their is a lot of radioactive Iodine floating around it and your body squirrels it away, that could be bad. That is why they hand out iodine tablets so you saturate your system with good iodine.
    3. The most important take away is that just because one little bit of radiation makes it way out of the reactor, it is not necessarily dangerous. Scale must always be considered. For example, we all heard about the Tsunami heading for Los Angeles after this quake – when the scale of that Tsunami was realized (i.e. about one inch in height), it hardly warranted the name Tsunami. In this case particulate counts, and radiation monitoring need to be done to properly assess the magnitude of the situation. I believe, due to the fact that Nuclear Power and Nuclear Bomb share first names, their tends to be a much greater fear of Nuclear Power than is warranted, and as a result cleaner better ways of using and employing this technology are not chosen. I am not saying it is without risk, but the engineering risks are manageable – often more manageable than basic things, like the levies of New Orleans. For some reason as a society we decide to accept certain risk as ‘just the way things are’, and allow ourselves no tolerance for risks in other areas. Often these areas are where the consequence is not clearly understood due to the complexity of the science or an unwillingness for us to keep an open mind earns certain areas like Nuclear Power the ‘boogyman’ label. When someone says that ‘radiation has leaked’ or 22 Japanese have been contaminated, those statements have no meaning without scale. Once the official reports and studies come out, and the scale is understood, I am sure the big media rhetoric will die down with no apologies. The anti-nuclear zealots will claim that the reports were misleading and filled with lies. And nuclear power will receive another ‘false perception’ based black eye, and because of the afore mentioned boogyman effect it will be hard pressed to redeem itself even if it is one of the most viable and greenest forms of energy currently widely available globally.


  115. Thanks Barry,
    I qualified as a Navy Nuclear Engineer, and worked on secondary side maintenance for commercial nucs for several years.

    Your article presents a pretty good layman summary of both the design and casualty situations for a BWR. While engineers can always fault you on some technical details, the thrust of your article is quite correct, in particlar that the risk to people ought to remain low, Japanese society is typically opaque on issues that might embarass, and that the utility will absorb a large loss on damaged equipment.

    Best Regards,


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  121. Informative but clearly written by pro nuclear lobby – how is this guy supposed to make accurate claims about the situation when he is sitting in some office on the other side of the world???


  122. In a practical sense, it sorta doesn’t matter what has precisely happened at Fukushima, the upshot is that this event is an unmitigated nightmare for the nuclear industry’ – just as it appeared on the verge of a renaissance.

    For nuclear devotees the aftermath will be a bitter pill to swallow, because unravelling what happened, and how close the nation came to disaster, will now preoccupy scientists and engineers for years to come.

    The first 30 years of nuclear power took place in the aftermath of the WW11 bombings of Japanese cities and then the protracted cold war, when nuclear armaments kept the clock hovering around one minute to midnight…. and then the accidents at 3 Mile Island and Chernobyl locked in people’s ingrained dread.

    25 years of breathing space and the climate change agenda finally brought nuclear power back onto political and commercial agendas and the tide in public opinion had only just started to shift favourably towards nuclear power in the past 5 years. Now Fukushima is to become a household word.

    Whether fear of nuclear power is justified or not, the industry is back to square one again. Well, almost. The majority of people out there aren’t nuclear scientists, suspicion of the dangers of nuclear power stem from a history that was not imaginary, it was very real.


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  124. @Heather Miller

    While you are correct, i.e.
    (10 ** 8.9) / (10 ** 8.2) = 5.01187234, there is no need to snipe at the author for a simple calculation error. This does not detract from the central argument in any way as far as I can see.


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  127. These figures ceratainly put things in perspective don’t they?

    Energy Source Death Rate (deaths per TWh)
    Coal – world average 161 (26% of world energy, 50% of electricity)
    Coal – China 278
    Coal – USA 15
    Oil 36 (36% of world energy)
    Natural Gas 4 (21% of world energy)
    Biofuel/Biomass 12
    Peat 12
    Solar (rooftop) 0.44 (less than 0.1% of world energy)
    Wind 0.15 (less than 1% of world energy)
    Hydro 0.10 (europe death rate, 2.2% of world energy)
    Hydro – world including Banqiao) 1.4 (about 2500 TWh/yr and 171,000 Banqiao dead)
    Nuclear 0.04 (5.9% of world energy)


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  131. A simple and unrealistic explanation…
    Anything can happen, there is already 2 explosions plus 2 more nuclear plants with problems, meanwhile radiation is been leaked to the atmosphere going to the air, earth and oceans…
    This articles could be good at explaning how nuclear planrs work but nothing valuable regarding what can happen in accidents… because no one knows…


  132. Nathanael, what you wrote is incoherent compared to Barry’s carefully detailed and informative piece. We certainly want an informed public, but what are we to make of statements like:

    ‘There will be a significant release of radioactive isotopes.’

    Our hospitals are full of radioactive isotopes. ‘Significant’? Good grief the sentence is meaningless, like legal jargon, ‘The party of the first part shall be known as the party of the first part’.

    If you’ve got something to say, you need to learn how to express it.

    BTW, you seem to be making a prediction, however ambiguously. So if you are wrong, will you recant?


  133. “On the other hand, actual nuclear professionals who work with this stuff every day and, therefore, have some respect for the limitations of the technology, have been alarmed by the steadily deteriorating situation from the beginning.”

    Rubbish. Completely contrary to the facts. actual nuclear professionals are at pains to explain that the situation is under control.

    [ad hom deleted]


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  137. Robert Green
    Do you understand the laws of libel?
    Barry Brook receives no remuneration from anywhere or anyone associated with the nuclear industry. All of the work on this blog is done in his own free time, using his own money, because he cares and because it matters. You can easily check that out for yourself (and Barry has already answered this criticism elsewhere).His only motivation is to find an answer to the developing climate change catastrophe and thereby prevent species extinction and civilization breakdown. A rogue always accuses others of his own motives because his character cannot see that anyone else would act differently. I strongly suggest you apologise to Professor Brook immediately.


  138. Could you keep your pro/con nuclear power comments out of this post for now.

    For all those in Japan (including myself), all we care about is our next move…and in order to be able to make it we need clear un-bias opinions.

    You can argue about it all you want when the situation is under control again.


  139. Death rates associated with various energy technologies do rate very positively for nuclear power, as reported by Ms Perps.

    In fact, if risk of reactor accident was the only sword hanging over the industry’s head then nuclear power could easily vie in popularity with other technologies (e.g. the motor car) that have an accident and death rate many hundreds of times higher.

    The problem for the industry partly stems from the fact that the invisible nature of radiation tends to spook people (falling off a roof whilst installing solar panels is, by comparison, a very obvious and direct way to risk being maimed or killed).

    Oddly there is an inordinate focus on the reactor safety issue, I guess because nuclear accidents are rather like planes falling out of the sky, in that they make for good dramatics. Per kilometre travelled, air travel is safer than car driving, bike riding or even walking, but the prospect of a plane crashing tends to spook people much more.

    What sets the nuclear industry completely apart is that it has to contend with an array of other perceived high-level risks in parallel – that is, the historic connection between the nuclear fuel cycle and worldwide nuclear arms proliferation and the seemingly eternal problem of waste disposal. With all that other appeasement baggage to contend with the last thing the nuclear industry would want right now is a reactor meltdown, even if a partial one.


  140. Thanks for the article, it has cleared up how the system works, and the redundant backup systems. I am still going to keep a close eye on the information coming out. Your assessment is too clean, it is based on probabilities. No one has actually seen the entire damage yet. If I have learned anything in this life its “if something can go wrong it probably will”. It is not over yet, until it is I will remain vigilant. respectfully jack


  141. The figures from the report I have linked to “Energy Death Rates per KWhr” are gathered from reputable sources such as WHO and have been published throughout the literature. Attribution is given in the article.[ad hom deleted]


  142. @ Ms Perps

    File that one under sample bias and Fun-With-Stats-and-Dick-and-Jane.

    To everyone else, the comments are HILARIOUS and worth a look. The author smacks of desperation for his headline; “Rooftop Solar More Dangerous Than Chernobyl”


  143. Jason
    You say:
    “Interesting article but your conclusions have just been proven wrong as a second hydrogen explosion just killed 6 workers at the plant.”

    What is the source of your information? This is what the authorities say:

    “Operator Tokyo Electric Power Co. confirmed that the 11:01 a.m. blast did not damage the container of the No. 3 reactor, allaying concerns that the explosion may have caused a massive release of radioactive substance.

    TEPCO said three workers, including its employees, were injured by the blast. All of them suffered bruises.



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  145. Great article, rather irritated at the people who didn’t appreciate the innuendos about Iran or the Soviet. I am a nuclear operator for the Navy and find that people ignorance with Nuclear Power is rather astounding. You have summarized this “tragic nuclear accident” rather poetically. Thank you


  146. Esquilax – stats with Dick and Jane – I don’t think so. They come from a highly regarded report done for the EU.
    The summary:
    “The risk comparisons are based on the results of the ExternE project (Ref. 1), which was
    financed by the EU Commission and carried out by research organisations in most EU states
    and in Norway. ExternE is one of the most extensive and scientifically most soundly based
    investigations within the field.”

    Here is the full scientific paper:

    Click to access 15%20-%20Polenp~1.pdf


  147. In discussing intermediate radio-active elements the author states “The challenge is that after inserting the rods and stopping the chain reaction, the core still keeps producing heat. “The uranium “stopped” the chain reaction.”

    This is last sentence is less than optimally placed. It reads as though (the) uranium moderated itself. Assuredly not the case. Perhaps it should read “neutron-inspired uranium-decay ceased.”


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  150. @ Ms Perps

    No, they’re correlating essentially construction deaths (questionable anyway) of solar PV installation before a TWh is produced.

    Where is the number of construction deaths before any of the NPPs produced an electron?

    On the mater of fossil fuels, obviously pollution there is causation. I have no problem with that.


  151. Anyway – I agree with Finrod or was it DV8 -enough feeding of trolls like esquilax – this thread is being derailed and is not about pro or anti nuclear arguments but rather to give honest, up-front information to those people concerned about the situation in Japan often because they are worried about friends and relatives there. Let us return to that subject.


  152. @ Ms Perps
    [ad hom deleted]

    The future reports will make very interesting and damning reading I am absolutely sure of it.

    In the meantime, I hope everyone stays safe, including the unfortunate workers making it up on the spot.


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  154. Excellent summary, but I believe a couple of things could stand to be cleared up.

    First, the term “meltdown” is thrown around the media pretty loosely but is not actually defined here, in the media, or in the nuclear industry. This presents a problem, so let’s define “meltdown.”

    In the past, before agenda-driven obfuscation became the norm in the media, a “meltdown” was understood to be when the uranium oxide fuel reached 3000 degrees and the separate pellets melted to form a single mass at the bottom of the reactor vessel. This mass would feed on itself to continue creating more heat, making it virtually uncontrollable. The popular theory went that this molten mass of fissionable material would melt its way through any material it came in contact with, including steel and/or concrete tertiary containment systems. This meant the mass could be neither controlled nor contained. Scary stuff indeed. The popular belief was that this mass of nuclear fuel would melt its way into the earth and melt a hole to China, hence the term “China Syndrome.” That’s where that sappy Hanoi Jane movie got its title.

    In any case, by this definition, melting at 2200 degrees of the Zircaloy tubes which contain the fuel pellets is not a “meltdown.” It’s a very serious problem, and a hideously expensive one for the plant owner/operator, but it is not a meltdown.

    This is an important distinction because of one technical point that was left out of this discussion. In the Three Mile Island (TMI) accident, the direct cause of damage to the reactor was some of the Zircaloy fuel tubes melting, allowing the fuel pellets to drop to the bottom of the reactor vessel. On the face of it this would seem to be a precursor to a meltdown. But it wasn’t.

    It’s important to understand that the fuel is uranium oxide, a ceramic, not uranium-235, a metal. Compared to metals, ceramics transfer heat very very poorly (that’s why they use ceramic tiles on the outside of the space shuttle), and have a very high Young’s modulus (i.e., let’s just say they are very brittle ). The result is that they easily crack and break apart when subject to uneven heating or cooling.

    Most people have seen what happens when one pours a hot liquid over ice in a glass container (for example, making iced tea) – the glass cracks. This is precisely what the fuel pellets at TMI did – they broke apart when they hit the relatively cool water, or steam, or melted Zircaloy, or whatever “coolant” was present and significantly cooler than the uranium oxide. When the fuel pellets break apart, they reduce their criticality and increase their surface area, which improves cooling. The result is that a meltdown becomes very difficult, if not a practical impossibility, to achieve.

    I used to work in the nuke industry. I worked with people who worked on the TMI cleanup. They showed me photos taken of the TV screens connected to their robotic cameras. One could see the remains of broken pellets sitting in a solidified mass of Zircaloy. They were surprised but relieved to see what had happened to the pellets. To them it meant that a meltdown would be very difficult to create. To me it means you would really have to work at creating a meltdown. I’m skeptical that a meltdown is even possible, but I could be wrong.

    Of course, if you have an agenda, you could call melted fuel tubes a “meltdown” but molten metal is pretty easy to contain and isn’t fissionable, meaning it can’t feed on itself to create even more heat to create the imagined “China Syndrome”.

    FYI: The TMI reactor was a pressurized water reactor (PWR), not a BWR like the Fukushima plant, but the PWR and BWR aren’t all that different in operating concept. The Chernobyl-type plant was a whole different animal, nothing at all like either TMI or Fukushima. Those comparisons are simply idiotic.

    I worked with a guy from Kiev before Chernobyl blew up. He used to tell me how dangerous Russian nukes were. After Chernobyl blew up I wondered if that was what he was talking about. I had lost track of him and couldn’t ask.


  155. Thank you SO much. With misinformed rumors and over-dramatized reports flowing over local communications, your report not only gives us foreign residents here in Japan an understanding of the situation, it also gives us peace of mind.

    With the continuing aftershocks and casualty discoveries, this is definitely a Godsend.


  156. Good summery of what has happened. However, after a series of things going wrong, the conclusion “nothing can happen anymore” is naive. As with any nuclear catastophe there is a whole chain of stuff going wrong at once, going through multiple layers of “depth of defense”. How e.g. can you be sure the core didnt get crack through the earthquake? Yes if nothing goes wrong anymore, the effects will result in only a few radioactive contained ruins, but thats no reason not to be careful and observant.


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  158. I’m still hoping for a detailed reply to my question about whether the very welcome post here applies to all the reactors at the facility. I have some very bad news, I’m afraid, for the fear-mongers who are trying to transform this crisis into a soap-box for their anti-nuclear hysterics. Kyodo is reporting that the state of emergency has been lifted for reactors 1 and 2 and that efforts are ongoing to keep the heat levels low at the remaining reactors. It appears that human error, a massive tsunami, and the most powerful earthquake in modern Japanese history combined could not damage a 40 year-old nuclear power plant built in one of the most unstable seismic regions on the planet. If that sounds like proof positive the technology is unsafe, you’re living on a different planet. We live about 200 kilometers from Sendai and understand that the situation is fluid.


  159. Jason; the 2nd explosion at Fukushima Unit 3 was planned. They didn’t know exactly when it will happen, but the Japanese Government thru Mr Edano, Chief Cabinet Secretary has already announced this explosion yesterday to win public confidence. This is just a hydrogen detonation, an announcement was made yesterday so that the public does not speculate along the lines of that it could be a nuclear chain reaction explosion.

    They announced that the explosion will happen today. But they didn’t know exactly when.


  160. so long !
    where is the summary

    the first picture “Boiling Water Reactor Design”
    Secondary containment : area of explosion
    Primary containment : remains intact and safe

    that enumeration differs from what he defines below

    The Zircaloy casing is the first containment.
    The pressure vessels is the second containment
    The third containment is a hermetically (air tight) sealed, very thick bubble of the strongest steel.
    This third containment is then surrounded by the reactor building.

    , a large and thick concrete basin is cast under the pressure vessel , which is filled with graphite, all inside the third containment.

    The reactor building is an outer shell that is supposed to keep the weather out, but nothing in. (this is the part that was damaged in the explosion, but more to that later).

    how much do each of these parts weigh, how big are they, are the proportions correct ?


    > the difference between the 8.2 that the plants were built for and
    > the 8.9 that happened is 7 times, not 0.7). So the first hooray for
    > Japanese engineering, everything held up.

    but the 8.9 (now 9.0) did happen in 120km distance and 16 km beneath the sea-level
    So, what happens when an 8.2 happens directly at the plants ? Still hooray ?

    > The tsunami took out all multiple sets of backup Diesel generators.

    would it have been so difficult/expensive to make them Tsunami-proof ?
    Just put them underground

    > So mobile diesel generators were trucked in.
    > the plugs did not fit

    ahh. Please say they were destroyed by the earthquake or such.
    Not just an oversight ?!?

    > Because cooling the core is such a big deal, the reactor has a number of cooling systems,
    > each in multiple versions


    > Which one failed when or did not fail is not clear at this point in time.

    no problem, we have multiple versions.

    > The temperature at this stage was about 550°C.
    > This is when the reports about “radiation leakage” starting coming in.

    > At some stage during this venting, the explosion occurred. The explosion took place
    > outside of the third containment (our “last line of defense”), and the reactor building.

    outside the reactor building ? Where then did it occur ?

    > And it did explode, outside the third containment, damaging the reactor building around

    OK, so apparantly that was a typo above. Replace “and” by “in”

    > The operators decided to vent the steam from the pressure vessel not directly
    > into the environment, but into the space between the third containment and
    > the reactor building (to give the radioactivity in the steam more time to subside).

    maybe to filter it by these hepafilters, which I had read elsewhere ?

    > The core is covered by several meters of water in order to allow for some time
    > to pass (hours, days) before it gets exposed.Once the rods start to be exposed
    > at the top, the exposed parts will reach the critical temperature of 2200 °C after
    > about 45 minutes. This is when the first containment, the Zircaloy tube, would fail.

    and that water level, is it known ? Is it being measured ? Did Tepco know about the
    actual situation all along but didn’t tell us (nor their injured workers) ?

    > uranium, was still under control, because the uranium oxide rods were good until 3000 °C.
    > … very small amount of Cesium and Iodine escaped

    > The water used in the cooling system is very clean, demineralized (like distilled) water.

    > In order to prevent a core meltdown, the operators started to use sea water to cool the core.
    > I am not quite sure if they flooded our pressure cooker with it (the second containment),
    > or if they flooded the third containment, immersing the pressure cooker

    > The plant came close to a core meltdown. Here is the worst-case scenario that
    > was avoided: If the seawater could not have been used for treatment, the operators

    …or, as was reported now (AFAIU) the whole plan had failed due to some leak …

    > would have continued to vent the water steam to avoid pressure buildup. The third
    > containment would then have been completely sealed to allow the core meltdown
    > to happen without releasing radioactive material.

    … and most importantly : without informing the public …

    > After the meltdown, there would have been a waiting period for the intermediate radioactive
    > materials to decay inside the reactor, and all radioactive particles to settle on a surface
    > inside the containment. The cooling system would have been


    > restored eventually, and the molten core cooled to a manageable temperature.
    > The containment would have been cleaned up on the inside. Then a messy job of
    > removing the molten core from the containment would have begun, packing the
    > (now solid again) fuel bit by bit into transportation containers to be shipped to
    > processing plants. Depending on the damage, the block of the plant would then
    > either be repaired or dismantled.

    OK. So how much damage would (did?) that cause Tepco ? Does it compare to the scenario
    that the newspapers drew (due to lack of information like this)

    > Now, where does that leave us?
    > The plant is safe now and will stay safe.

    but now we have problems with #3 which is another type and the cooling of #2 is reported to
    have failed too and possible problems in other plants too and aftershocks and injured
    workers, so we don’t know whether there are still people let to do the job.

    > If you want to stay informed, please forget the usual media outlets and consult the following websites:

    http://www.world-nuclear-news.org/RS…1203111 .html

    > 233 Responses

    I’m not going to read all these


  161. Thanks for putting this up..

    I am in Japan at the moment and can’t believe how the world media is sensationalizing this. Sure it is a serious problem, but nuclear physics is not something to be sensationalized.

    I think people need to take a chill pill about the nuclear plants and think about the tens of thousands of people who are dead from the tsunami. The Japanese authorities are literally finding beaches with hundreds of bodies and people are worried about 3 people having mild radiation exposure.


  162. Many thanks for the informative article.
    I find it a really well thought out article at attempting to explain how nuclear reactors function.

    Unfortunately I have the same questions as many other people here and I frankly find it very unsettling that despite going to such pains to write an easy to understand article in the attempt to set the record straight – you and many of the commentors (who purport to have some sort of qualification when it comes to nuclear energy) seem unable or unwilling to answer some basic questions regarding radiation leakage.

    It has been reported that some 200 people are now being treated for radiation poisoning.

    Low level radiation has been detected some 60 miles down the coast from Fukushima.

    The US have withdrawn their fleet from the Fukushima area after detecting low level radiation.

    For all these reports surely if the radiation only lasted for a few seconds then no-one would be suffering poisoning and radiation (even low level) would not be detected up to 60 miles away from the plant.

    Finally – and this is a big one – I can’t wait for someone to answer this one –

    Why bother attempting to salvage the reactors if even a complete meltdown is completely safe and poses no risk to anyone ever? One of them was due to be shutdown forever anyway? Why bother attempting to cool it?

    Reports are that now that they are using sea water to cool them – they are effectively useless and will be unable to be used again. So why bother?

    Someone is not telling the full truth somewhere – if the reactors really were completely safe – just just the plant and walk away – as it is there have been numerous casualties now at the plant which going on your advice is a pointless exercise if there is no risk anyway.


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  164. Andrew Jones, what he said, there are multiple layers to hinder nuclear and toxic material to get into the environment. Some have failed, some are crticial and another one (the core catcher) is still in place.

    However the conclusion “it is 100% safe” is wrong. We can’t be 100% certain the other layer will also fail out of this or that unforseen event. And it is not futile to work on inner layers, as long they didnt fail completly. Also there is a difference in how big (and expensive) the radioactive ruin is going to be.

    Contrary to this autor a true expert will tell you there are different scenarios that can happen (where this one is merly the optimal case from this moment on.)

    About the news of radiation poisining I wonder as well. Fact is, news are contradictive and filtered. Nobody except the japan government and the company operating the plant do not know what is really, really, happening. And even those cannot look into the reactor cores.


  165. I can not believe the television stations here in australia, they have been sensationalising the
    reactor and explosion to the extent it is beyond belief.
    Prime television which has national coverage here in oz ,announced this afternoon that their was a second explosion and in the same sentence said that 2,000 bodies were found on the beach, insinuating the explosion was the cause of these deaths, the disaster is bad enough and the suffering of the Japanese people, let alone all this rubbish being released by the media here in oz my heart goes out to the people of japan.


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  169. Thank you very much for detail explanation. Please let me ask a couple of questions, and I would be thanking you very much if you would give a lecture.

    I am familiar with neither nuclear technology nor quantum physiology. I wonder nuclear fisson might be going on more or less, due to partly malfuntion of control rods: which worked as they should at the first impact (ground shake), but during the Tsunami or second/third thrust, some of them may fall down (Japanese BWR designed to insert the rods from the bottom, not along gravity…my understanding). I would be very happy if you tell me your professional opinion on this possibility.

    Second one, pure-water first, and now sea-water is pumped into the reactors (the reports do not tell which comaprtments, though) for long time: while the ECCS are designed to use a limited amount of reserved pure-water. Given the amounts of uranium/prutonium there and how long the fuel has been burned, it would be not difficult to calculate the expecting heat generation during shut-off. The amounts of water/sea-water putted in are then comparable what they should be ?


  170. I found this post very informative, however biased…

    There will still remain some misunderstanding between people considering a realease of Cesium and radioactive Iodine as a success, and those seeing the failure and the lies.

    You say “science”, I see inconsistancy.

    Don’t try to change people’s vision, change what they see, act better!


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  172. Why bother attempting to salvage the reactors if even a complete meltdown is completely safe and poses no risk to anyone ever? One of them was due to be shutdown forever anyway? Why bother attempting to cool it?

    Because if a meltdown happens, Chernobyl 2 happens. They’re not attempting to salvage it at all. Using seawater to cool the reactor spells the death knell for the reactor since the corrosion on the equipment will make the whole thing unuseable. It’s not salvage, it’s a desperate attempt to prevent a catastrophic explosion.

    The US have withdrawn their fleet from the Fukushima area after detecting low level radiation.

    —-After detecting radiation 100 miles offshore! I’d call that a significant release of radiation.

    They never tell the full truth in these matters. There’s the wider issue of chaos and panic to consider in an already disaster zone. There simply isn’t the infrastructure to cope with every Japanese individual trying to escape a possible nuclear blast, whether or not they’re at safe distance. So you never admit impending doom.


  173. Thank you to those who have answered my questions – here are some more.

    Why does the author (and some commentors) claim the half life of Iodine and Cesium to be so short that it will cause no problems to anyone – and yet the US EPA says that Cesium has a half life of 30 years and Iodine a half life of 8 days (but roughly 100 if it gets into the body)

    Google “Cesium EPA”

    Both of these timescales seem to be considerably more than “a few seconds” to me?


  174. “They never tell the full truth in these matters. There’s the wider issue of chaos and panic to consider in an already disaster zone. There simply isn’t the infrastructure to cope with every Japanese individual trying to escape a possible nuclear blast, whether or not they’re at safe distance. So you never admit impending doom.”

    If the facts don’t fit your belief that something very bad is happining, it must be a cover-up.

    Oh Eric Moore, tobacco health issues were well known and no one covered them up. The tobacco companies tried to claim thet did not know about it, Please get your history straight.


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  177. Why does the author (and some commentors) claim the half life of Iodine and Cesium to be so short that it will cause no problems to anyone – and yet the US EPA says that Cesium has a half life of 30 years and Iodine a half life of 8 days (but roughly 100 if it gets into the body)
    [ vulgarity removed]
    But you’re correction, the half-life is 30 years.


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  179. If the facts don’t fit your belief that something very bad is happining, it must be a cover-up.

    If you want to cause a giant panic in an already stricken country, then be my guest. But the result would not be pretty at all. And more people would die.


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  182. nobody believes in what the PRO-Lobbyists preach anymore.

    in case you missed it: Fukushima Reactor 2 is dry. out of water. the trials to cool it down with seawater FAILED.

    Switzerland decided not to build new nuclear power plants. more countries (with people who got some brains) will follow….


  183. This blog is being cited because the public wants to believe that the engineers in charge have anticipated all the possibilities and are properly managing the partial meltdowns. OTOH, it is clear that several unfortunate unanticipated events have occurred (diesel generator flooding, mismatched power source wiring, hydrogen explosions in or near the secondary containment). Now we are seeing some radiation danger to workers in the plants (can they not be remotely managed using PCanywhere or Remote Desktop Connection?), with significant consequences (just like 3-mile Island) because workers cannot risk exposure over long periods. We have also learned that there is no ‘core catcher’ as this blog suggests.

    Japan is a physically small country with a huge population and cannot afford to give up any significant real estate for any significant period of time. Consequently, the rosy scenarios seen by many will not come to pass. The technology for clean up will have to progress and “safe” storage for all the waste will have to be found. This will not be quick or easy.

    As a scientist I am hopeful that all the problems can be solved with a minimum loss of life. As a pragmatist, I am aware that there will clearly be (have already been) some casualties in this accident. My hope is that there will be as few as possible going forward and that ‘normalcy’ will return rapidly. That is certainly what the blogger that wrote the original comments intended.


  184. Hi Barry,

    Could you give an update on the situation right now? The media are talking about cores without cooling and a possible meltdown. A far worse situation than described in your, by the way excellent, article. Is it really getting worse? I hope you can and will respond.

    Thanks in advance!


  185. “Why does the author (and some commentors) claim the half life of Iodine and Cesium to be so short that it will cause no problems to anyone – and yet the US EPA says that Cesium has a half life of 30 years and Iodine a half life of 8 days (but roughly 100 if it gets into the body)
    -Because some people will invariably talk out of their arse. But you’re correction, the half-life is 30 years.”

    Well, it depends what isotopes you’re talking about, of course.

    Yes, the half-life of caesium-137 (which is a significant moderately long lived fission product, responsible for most of the radioactivity contained in used nuclear fuel) is 30 years.

    But there’s absolutely no reason to expect that anything but the tiniest little traces of radiocaesium will be released at Fukushima.

    What is the natural background level of Cs-137 in the environment in Japan, due to things like the atomic bombs, anyway?

    Some media outlets say radio-Cs has been detected… but nobody has ever said quantitatively how much (remember that measurement is extremely sensitive) nor have they said that it was actually above existing background.

    The half-life of I-131 is not “100 days if it gets into the body”. Maybe that’s its biological half-life for excretion and turnover within the body, but its physical half-life for radioactive decay is still 8 days.

    Many drugs and the like follow an exponential decay as they’re eliminated from the body – so you talk about the biological half-life.

    If you’ve got a radioactive chemical or radiopharmaceutical, with a certain physical (radioactive decay) half-life (which depends on the radionuclide) and a certain biological half-life (which depends on its chemical form), then to plot the decay of the amount of radioactivity in the person’s body as a function of time then you need to add together the exponential decay constant for the physical decay and the decay constant for the biological decay.


  186. Barry, Kyodo is now reporting that some of the rods in Number 2 may have already melted. The best case reporting for that reactor reported 30 centimeters of water in that reactor. That’s about 10 inches, most of which must have been converted almost immediately into steam, if I understand the processes taking place. TEPCO is venting the steam as I tap. We need to get a clearer picture of what happens if these rods melt, please. I strongly suggest you address questions from pro-nuclear visitors and ignore the camp that has already determined the outcome irrespective of the actual facts.


  187. Fukushima No. 2 reactor’s fuel rods fully exposed, melting feared

    TOKYO, March 14, Kyodo

    Fuel rods at the quake-hit Fukushima No. 1 nuclear power plant’s No. 2 reactor were fully exposed at one point after its cooling functions failed, the plant operator said Monday, indicating the critical situation of the reactor’s core beginning to melt due to overheating.

    The rods were exposed as a fire pump to pour seawater into the reactor to cool it down ran out of fuel, Tokyo Electric Power Co. said. The firm had reported the loss of cooling functions as an emergency to the government.

    TEPCO said water levels later recovered to cover 30 centimeters in the lower parts of the fuel rods.

    The seawater injection operation started at 4:34 p.m., but water levels in the No. 2 reactor have since fallen sharply with only one out of five fire pumps working. The other four were feared to have been damaged by a blast that occurred in the morning at the nearby No. 3 reactor.

    The utility firm said a hydrogen explosion at the nearby No. 3 reactor that occurred Monday morning may have caused a glitch in the cooling system of the No. 2 reactor.

    Similar cooling down efforts have been taken at the plant’s No. 1 and No. 3 reactors and explosions occurred at both reactors in the process, blowing away the roofs and walls of the buildings that house the reactors.

    It is feared that the No. 2 reactor will follow the same path. To prevent a possible hydrogen explosion at the No. 2 reactor, TEPCO said it will look into opening a hole in the wall of the building that houses the reactor to release hydrogen.

    The company has also begun work to depressurize the containment vessel of the No. 2 reactor by releasing radioactive steam, the government’s Nuclear and Industrial Safety Agency said. Such a step is necessary to prevent the vessel from sustaining damage and losing its critical containment function.

    With only one fire pump working, TEPCO is placing priority on injecting water into the No. 2 reactor, although both the No. 1 and No. 3 reactors still need coolant water injections, according to the agency.

    The blast earlier in the day injured 11 people but the reactor’s containment vessel was not damaged, with the government dismissing the possibility of a large amount of radioactive material being dispersed, as radiation levels did not jump after the explosion.

    TEPCO said seven workers at the site and four members of the Self-Defense Forces were injured. Of the 11, two were found to have been exposed to radiation and are receiving treatment….


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  189. Fear not, as we already know by this simple and accurate explanation what happens next:

    “Here is the worst-case scenario that was avoided: If the seawater could not have been used for treatment, the operators would have continued to vent the water steam to avoid pressure buildup. The third containment would then have been completely sealed to allow the core meltdown to happen without releasing radioactive material. After the meltdown, there would have been a waiting period for the intermediate radioactive materials to decay inside the reactor, and all radioactive particles to settle on a surface inside the containment. The cooling system would have been restored eventually, and the molten core cooled to a manageable temperature.”

    By the book, that is.


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  193. My last comment got deleted for some kind of violation. I am just wondering why the link bzb posted has a right to stay as he calls this ‘information’. A link to a site where Chernobyl is called a bluff. If you want to keep your article at least a bit credible, you should get rid of this link, too, as you did get rid of my comment to it. it is kind of off-topic anyway.


  194. “m” proves to me once again that insult is the last refuge of the incoherent.

    The Japanese recovery workers are doing the very best with what they have. Reactor decay heat is decreasing steadily, as it always does after shutdown.

    The situation is improving, not degrading. A large release is becoming less and less likely as time goes on,


  195. Your synopsis implies that the pumping of sea water into the cores has cooled them. This isn’t precisely the case. The pressure inside the chamber is so great that they are having a hard time getting the water in with the firefighting equipment (yes, fire hoses) they’re using. On top of that, their instruments are likely not giving accurate readings, so they’re working somewhat blind. While they are able to keep the reactor from going into total meltdown, they aren’t able to get it sufficiently cooled to have it “off”.


  196. I hope you guys are right, however you seem to be very self righteous which makes me worry. I am not sure if nuclear is good or bad for the long term in our world, but one thing is sure I don’t think I can trust people with commercial or political interest in nuclear power. Humans are naturally only concerned with short term interests. Money is the biggest driver both for individuals and governments. I get very annoyed that so little is spent in research to do with renewable and, even more importantly, energy efficiency projects are too slow and again not funded properly as far as I can see.


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  199. Eric – this is a 40 year old reactor surviving with only minimal low level radiation releases what was one of the largest earthquakes recorded and a 10m Tsunami to boot! 10,000+ people are dead, pretty much everything in the path of the Tsunami was wiped off the face of the planet, and yet these reactors are holding together. Sure there are issues, and no one is denying that something else COULD go wrong even if highly unlikely, but right now the media should be calling a spade a spade and celebrating that these reactors are intact, in spite of commercial or political interests.

    Media is reacting as though this is already Chernobyl, or will almost definitely be Chernobyl, but it’s not. It’s a goddam celebration of engineering safety!


  200. I am not doubting that anyone is doing their best.
    Doing the best just doesn’t always mean, someone’s doing the right thing…

    And reactor heat is increasing steadily after an expolsion occured. ….I am correcting myself: there have been two detonations this morning.


  201. Kyodo:

    BREAKING NEWS: Fukushima’s 3 reactors highly likely facing melting: Edano 9:41 Tokyo time.

    It is quite possible that the engineers will be able to pump enough sea water into the three reactors over the next 48 hours to prevent a major disaster. But the best case scenario seems to call for the venting of a lot of radioactive steam. I’m still unclear what the worst case scenarios look like. Mr. Edano states that a worst case scenario like Chernobyl is highly unlikely. So, what are some of the likely worst case scenarios?


  202. Matt – I do hope you are right and I am following all commentators on this, because I know there is media hype, self interests and ignorance (I am sure I probably fit into that label). As long as in the long run there is total openness and lessons learnt, I will be happy. I hope Japan gets back on it’s feet and that the people immediate requirements are put before big financial interests.


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  204. All of what we actually _see_ here in the reports doesn’t fit the “good news” presented here.
    This is just a personnel, unqualified judgment but I’d bet that at least for reactor #1 the containment vessel is _not_ intact (or at least the cover is not) while the reactor pressure vessel still is. You just don’t get the kind of explosion we’ve seen at #1 from hydrogen burning in an unpressurized environment without high levels of oxygen.
    This is how high levels of hydrogen burning with atmospheric oxygen under perfect conditions look like (lots of excess hydrogen is released during engine startup):


  205. the media is not reacting as this is another Chernobyl. actually everyone hopes it will be not. and it is not about comparing one desaster with another anyway. the politicians and people are reacting! they simply see that nuclear power has risks which we should think about if we are willing to take them. that is what is happening.

    and it is no celebration of engineering safety. those guys were lucky (lucky?! what the head i am saying…) …well, lucky not more has happened yet….or lucky, that nobody really knows what actually happened.

    it is legitimate to observe a happening and make one’s own conclusion. if some people decide that there are alternatives….why is it so hard for you respect this?


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  207. Once again “m” has it wrong. The Japanese responders are doing just fine, thank you. They are doing the right things.

    And reactor heat production is NOT increasing. Read the recent statement by the Japanese Atomic Industrial Forum. Good news all around — and true.

    Every time the pressure of the primary containment is relieved we can expect a hydrogen explosion. Even at atmospheric pressure, hydrogen is combustible above about 4 percent concentration. The secondary containment atmosphere is air, after all, especially after the roof has been blown off.


  208. I totally understand that people who own their bread in the nuclear biz stand in for it. I respect that. I probably would do the same. It is like a discussion between mac-users and the rest of the PC-world. Everyone believes what is already closest to their believes. Before those incidents I must admit I hadn’t any clear opinion concerning nuclear power plants, though I remember how frightened I was as a kid when Chernobyl happened. It didn’t make me an active anti-nuclear-person. I was still open and observing. But after all this I cannot stay neutral anymore. I am not doubting the know-how of people who work in the business, BUT it is frivolous to claim to exactly know what is going on inside this reactor (just as frivolous as shouting: Chernobyl, Chernobyl!). And exactly this is why I decided not to be pro. We just cannot foresee anything. And with this knowledge nuclear power plants are like an army of Pandora’s Boxes. It is just about measuring the risks. If there is no better alternative than living with this fear than – I am sorry – we haven’t thought about it hard enough. Nuclear Power seemed to be a short-cut when mankind came up with, but we may not survive it…


  209. Barry,
    I have been looking for a post like this to counterbalance the mindless, sound-bite reports that don’t care to tackle any of the science.

    Thanks for taking the time to explain what is going on in rational terms. Even though the situation is changing and not all information is known, at least you try to go through what you know in a rational fashion.

    Whether one likes nuclear power or not, an attempt to get to the facts is necessary, and this is one of those efforts. Thanks!


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  211. I am a health physicist (radiation safety expert) with advanced degrees and 30 years experience in US nuclear power and USDOE experience. I have been reading this and the comments, but alas hesitate to express my opinions due to the nasty attacks of the anti-nuke trolls. The article is mostly correct in the technical details albeit a few minor errors about the accident(s). It is hard not to be seen as self-righteous when accosted with emotional attacks that do not have any scientific basis. That said, it is not the time now to sit back and say everything is fine, as the situation is still serious for the site.
    For those who are reading this in Japan, the event is not over yet and the findings of airborne radioactivity plumes 100 mi. from shore and 30 km down from Fukushima are alarming – however they are not an emergency, especially if they are only the short-lived I-129 and 131, and other radionuclides from the decay neutron activation of air, water, and sea water. Tritium is especially weak as a hazard, even with its’ long half-life, due to the very weak radiation emissions. The cesium-137 and Sr-90 (if indeed these are the isotopes detected) are another matter, but as previous bloggers have stated they should likely be in much smaller quantities – and I understand the prevailing winds normally blow from E or SE so the plume is going offshore. Also, neither explosion was large enough (in my opinion) to eject particulates high into the atmosphere, nor has there been any report of fire, so comparisons with Chernobyl are ridiculous. However, listen to, and follow any of the guidance being given by authorities. They are using protection guidelines that are extremely conservative and will keep you safe.

    Finding any hard numbers for the extent of the exposure or release has been extremely frustrating, and I have not found one single use of the correct terminology in the media yet for radiation dose or dose rate. It has been stated that the radiation level in the control room of unit one is 1000 mSv. That is meaningless with out the RATE – per hour ??? per day? Converting to US units (sigh…) and wildly guessing it means 10 rem/hr, then the control room is uninhabitable. I doubt that is the case unless the spent fuel pool really has been drained of cooling water and there is spent fuel in there. Another report from TEPCO stated one employee has received a radiation dose of over 10 rem. How much over? Radiation non-stochastic effects (prompt effects) start at about 50 rem absorbed dose.
    The US Navy report from the USS Eisenhower stated that the radioactive plume the sailors were exposed to “was only exposing the personnel to the same dose from natural background they would receive in one month”. A little radCon math tells me that exposure was ~30-40 mrem. If they received this in an hour, and this was in fact 100 mi. from shore, than this is a significant plume from the accident and is not a short-term ‘puff’ release. Of course it also means the reactor containments are not effective, which is to be expected when venting off steam from the PV. However, I doubt very much this is correct, because site boundary instruments are not reading above 5 mrem/hr from my reading, and even Chernobyl did not approach such doses at that distance.

    One comment on the original article I disagree with is the results of the full melt-down of the fuel, whether it is the Low-Enriched U fuel of Unit 1 or the MOX (mixed Pu-U) fuel of unit 3. There is no possibility the reactor containment will seal in a melt-down. If the water completely boils off in the vessel and cannot be replaced – unlikely, but if it is really true that the only emergency pumps are fire pumps and they are running out of fuel, possible – and the fuel/zirconium mixture melts and begins burning, and there is now no reactor building left over each unit……well, it will be a ‘mini-Chernobyl”, for lack of a better laymans’ term. Lets all hope and pray they can restore power, and decay-heat removal cooling continues as the workers are valiantly trying to ensure.
    It could have been MUCH worse.


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  213. Sad that “m” feels he must discredit the professional ethics of all the expert and well-meaning people who work in the nuclear industry around the world, in order to support his own point of view.

    As a professor almost ten years past retirement, I am quite independent in both my finances and profession. I am more that a little offended by this attitude.


  214. From the Guardian:

    2.13pm: Justin McCurry, the Guardian’s Tokyo correspondent, emails to say the water level inside the No. 2 reactor at Fukushima Daiichi nuclear power plant has recovered to a level of about two metres, according to Kyodo News. The rods were fully exposed for about two and a half hours, according to Japan’s Nuclear and Industrial Safety Agency.


  215. I’m assuming that some people are giving their lives (or many years of their lives) to prevent a worse catastrophe. I would probably refuse to continue working there even if I was one of the critical engineers needed to save the situation. Also, there is no “celebration of engineering” element in allowing any of these 40 year old reactors to keep working. It sounds like massive bad luck that at least one reactor was supposed to shut down permanently just about the time the tsunami happened. We will see the public shut down many Mark I’s around the world soon. Smart people will be saying “if it doesn’t have a core catcher” it isn’t going into my backyard.”

    I mean, after all, with a “core catcher”, it won’t hurt anyone’s real estate value to be located 5km from a nuclear power plant, right?

    I’m sure the pro-nuclear people will volunteer to have at least a PRISM reactor located 5 km from their real estate.


    Why am I hearing crickets chirping?

    By the way, are their advantages to a PRISM reactor?


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  219. Everyone with political or economic decision making power regarding nuclear plants, should be required to put a significant amount of their personal fortune into local real estate.

    Here is important info on the Mark I from GE that was noted for its “cost-saving” inadequacies compared to competitors 40 years ago:

    However, as early as 1972, Dr. Stephen Hanuaer, an Atomic Energy Commission safety official, recommended that the pressure suppression system be discontinued and any further designs not be accepted for construction permits. Shortly thereafter, three General Electric nuclear engineers publicly resigned their prestigious positions citing dangerous shortcomings in the GE design.

    An NRC analysis of the potential failure of the Mark I under accident conditions concluded in a 1985 report that Mark I failure within the first few hours following core melt would appear rather likely.”


  220. In the Hazards of Boiling Water Reactors in the United States one sees that venting was expected for Mark I’s in 1986, which means it’s been considered an “acceptable risk” by governments and industry people since then.

    You can’t fault GE because they would have gladly had their old systems replaced with new ones. It sounds like, just as many first world dentists have more dangerous x-ray and other equipment than third world dentists, there’s been a lot of greed going on where companies were trying to get for their shareholders immense profits based on the idea that their capital expense was realized 40 years ago or 25 years ago.

    It is unconscionable that, at the time of Chernobyl, these Mark I’s were known to be at high risk for “venting events” but this was considered “acceptable”. Politicians have been getting lobby money for sure.

    Real estate values around all Mark I BWR reactors should be plummeting about now, as people learn what they are = dangerous cash cows.


  221. Dr. Meneley says,

    Sad that “m” feels he must discredit …

    Or anyway he feels it’s clever to try — under a pseudonym!

    It was good to hear you talking to Wei Chen on the CBC. They’ve been doing some things right. Another is to talk about the radiation levels at the afflicted plants in terms of transpacific airline flight exposure.


  222. Peter, I think that Chernobyl is an entirely inappropriate point of reference to use in any context, no matter how you qualify it.

    If there is a full core melt, and if somehow (despite our knowledge of what happens from Three-mile island) the melt penetrates the reactor vessel, there is still the next layer of containment for the melt, much of which will not leave the reactor vessel anyway (3MI again), diluted with steel. Your assertion that “there is no possibility that the reactor containment will seal in a melt-down” seems without ground.


  223. Two questions:

    You say: “The intermediate radioactive materials (Cesium and Iodine) are also almost gone at this stage, because the Uranium decay was stopped a long time ago. This further reduces the activation.” 137-Cs has a half-life of over 30 years, the Chernobyl cesium is still around all over Europe. Iodine has several isotopes with half-lives of a few days, implying a high intensity in the next couple of weeks. How do you arrive at your conclusion that the “activation” – whatever you mean with this imprecise term – is reduced?

    “The reactor core will then be dismantled and transported to a processing facility, just like during a regular fuel change.” Do you seriously think it will be easy to dismantle a (partly) destroyed, highly active reactor core?


  224. Thanks a lot for this. Very informative. I gave up on the MSM for accurate info a long time ago.

    It’s probably too late, but I was wondering if you could explain one or two points. If (as I understand it) the Cesium and Iodine naturally breaks down into non-radioactive elements, why does some Cesium or Iodine have to be removed from the cooling/ sea water as radioactive waste?


  225. ‘The radioactive nitrogen as well as the noble gases do not pose a threat to human health.’

    does this meant to living creatures (fish, squid…) as well? So we still can eat sushi?


  226. Eric Moore, on 14 March 2011 at 11:39 PM said:
    I hope you guys are right, however you seem to be very self righteous which makes me worry. I am not sure if nuclear is good or bad for the long term in our world, but one thing is sure I don’t think I can trust people with commercial or political interest in nuclear power.

    Look at it this way: both before and after the tsunami, Japan was full of fuel burners and fuel that routinely killed people. The fuel was heavily taxed. So you could say that for each $billion government got, someone had to die.

    And not only could you say it, it’s the whole truth, up to perhaps some inaccuracy in the $1 billion figure. But obviously it doesn’t make much difference if it’s ten billion or 100 million.

    And the (Teller-approved) nuclear power deal was always, give up that billion, Mr. Tax Man. You don’t need it, and you’ll save the victim that it requires. And the answer has always come, “Oh, goody. Excellent. just excellent. Um … with due deliberation, and if we can get it by the public, of course.”

    And the deal hasn’t changed. Teller-approved reactors still haven’t harmed their first neighbour. But notice how enthusiastically public money takers have been grinding their axes in the hope that it might!


  227. Let me repeat myself:

    High level Atomic Energy officials wanted Mark 1 reactors banned 40 years ago. See http://www.nirs.org/home.htm

    This was entirely preventable even if one wasn’t stupid enough not to build for the most powerful earthquake and tsunami effect theoretically possible (rather than the most powerful experienced in the meer 100 years before). One has to read “The Black Swan” and prepare for the worst case theoretically possible and not the worst case ever before seen. You have to prepare as if you own the real estate immediately downwind.


  228. McMike at 1:14AM, 15 March.

    You do understand, don’t you, that even if there had been a core meltdown, it would have been held within the containment vessel, and not entered the environment? Did you actually bother to read the article?


  229. “You do understand, don’t you, that even if there had been a core meltdown, it would have been held within the containment vessel, and not entered the environment? Did you actually bother to read the article?”
    Yes, we read the article and it’s just plain wrong in this point.
    The article also states that the reactor had a core catcher which is also just plain wrong.


  230. i admit I am ignorant and relying on you guys to tell me more. I have been reading Masashi Goto’s comments. I think he might be the reactor designer. Should I believe him?

    1431: More from Japanese nuclear engineer : He say that as the reactor uses mox (mixed oxide) fuel, the melting point is lower than that of conventional fuel. Should a meltdown and an explosion occur, he says, plutonium could be spread over an area up to twice as far as estimated for a conventional nuclear fuel explosion. The next 24 hours are critical, he says.
    1426: Mr Goto says his greatest fear is that blasts at number 3 and number 1 reactors may have damaged the steel casing of the containment vessel designed to stop radioactive material escaping into the atmosphere. More to follow.


  231. I think the big problem here was the following: The Fukushima plant uses seawater drawn in to condense the steam after it exits the power turbines. You can look at Google Maps and see the seawater inlets behind the seawall, and see the seawater outlet as well. This is a normal method for cooling a power plant.

    When the tsunami hit, it likely dredged up massive amounts of silt (just look at the after photos of all of the mud and silt in the towns), overflowed the seawall, and deposited that silt into the seawater inlets, clogging them.

    So even with backup power, seawater could not be drawn in to condense the steam back to liquid water.


  232. Although I appreciate this technical explanation of what went wrong in this nuclear plant, I do not like the way these facts are used to ‘promote’ nuclear power.

    I find this quite ‘uncivilized’, knowing that 200.000 people are evacuated, one person is dead and several are wounded (as mentioned before). And the article also states that the Japanese people are going to have to pay more money for their electricity bill in the coming months.

    Knowing all this, I can not imagine that the Japanese are prepared to take more risks related tot nuclear power plants in the future, just to prevent global warming. After all, why should they be scared of slightly higher sea levels after the events of the last four days?


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  234. One point for the pro-nukes is that, if left wing groups have been preventing the building of safer nuclear plants that would have already replaced the older ones, then they’ve been part of the problem and the reason why so many Mark I’s are still operating around the world.


  235. So this all comes down to Plugs not fitting together to be able to use the portable generators!
    A multi million dollar complex and not one Electrician around to wire these cables together!
    You do not have to have a plug in to conduct electricity
    Just a conductor!


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  237. 1422: Japanese engineer Masashi Goto, who helped design the containment vessel for Fukushima’s reactor core, says the design was not enough to withstand earthquakes or tsunamis and the plant’s builders, Toshiba, knew this.

    1426: Mr Goto says his greatest fear is that blasts at number 3 and number 1 reactors
    may have damaged the steel casing of the containment vessel designed to stop radioactive
    material escaping into the atmosphere.

    Should a meltdown and an explosion occur,…The next 24 hours are critical, he says.


  238. Frank said: “The plugs on trucked in temporary diesel generators did not fit? Did anyone in Japan ever heard of temporary connection rigging. Or is the status quo in Japan entrenched like here in US where electrical inspectors will threaten you with multi million dollar fine if you don’t comply with polished electrical code so the guys who try to help in emergency will spit in disgust and walk away? 8 hours is very long time in which temporary electric power should be connected by any means or batteries should be charged with temporary hook-up to prolong the time. Most electrical engineers will be scratching their heads why this was not done in 8 hours time.”

    Frank, I think that we’re talking 100s of KVA needed to run the coolant pumps. You can’t exactly splice those wires without dedicated tools. You need a hydraulic ram with correct die to do attach lugs to the wire. You can’t do temporary insulation using electrical tape either. It just takes ONE missing piece for the job to be stopped. You don’t have the right die for the size of the wire available, or you don’t have the lugs, or, or, or. It’s very easy NOT to be able to do such a job when it’s unplanned for.


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  241. To “prepare for the worst case theoretically possible”. An interesting concept…. Before leaving home tomorrow morning, think what is the “worst case theoretically possible ” and then think again about going out.

    Designs need reduce the risks so that they as low as reasonably practicable.

    Now, however, is not the time for additional speculation by those who have limited information and have a wish to exaggerate. Leave that to the journalists and politicians in countries such as Switzerland…

    But seriously, truly sincere wishes to all our peers and all other caught up in the evnts in Japan. Particularly those on the NPP site who are working to make the plants safe and minimise radiological releases. Heroes one and all.


  242. Question: Fukushima differs from Chernobyl mainly in that the control rods never got back into the core at Chernobyl. Correct? The Soviet plant remained critical as it burned, right?

    If that is the case, then can a misshapen, melted core in Japan go back to criticality?

    Is boron being flown in? How much boron does a plant keep on hand?

    Would Mark I reactors not located next to lots of sea water be more dangerous?


  243. It is indeed paradoxical to conclude from the current situation that nuclear energy is safe and controllable.

    It is laudable to what extent the reactors held up to an earthquake that they were not designed for, but then, the reactors were – in hindsight – obviously deployed in a place they were not designed for.

    And that’s the problem. You can’t sell nuclear reactors as ‘safe’ as there always will be unexpected events or chains of events which were not included in the design, and will lead to violation of safety, in the form of unplanned release of radioactive materials.

    Keep in mind that while this looks like a prood of robustness of those reactors how lucky we are that the winds don’t blow towards tokyo right now. While the ‘just an X-ray’ is true, it still means that the downwind regions are uninhabitable as long as the reactor cooling doesn’t become a lot less haphazard.

    So ‘nuclear power is safe, except when something unexpected happens, then better be prepared to evacuate large swaths of the country’ may be closer to the truth, and one that isn’t exactly likely to win the population.


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  246. Designs need reduce the risks so that they as low as reasonably practicable.

    No, no and no. This is wrong.

    Read “The Black Swan” to understand that, with nuclear power, you don’t prepare for the practical, you prepare for the 2000 year event, because a 2000 year event can occur at any time.

    If you are from the Depleted Uranium site, believe me, there attitude of hubris will not play. They say there that “pro-nukes should not apologize” and use other arguing techniques that just aren’t going to fly with intelligent people nor the general public. Those Mark I’s should have been taken offline 40 years ago.

    Those of us with conservative politics need to be very careful of pretending that only liberals (left wingers) care about their real estate and the milk supply and the food supply in terms of possible contamination in the interest of corporations they do not personally own shares in.

    Scenario: Obama campaigns for 2012 that all Mark I’s need to be decommissioned fast. Republicans say this is hype. Several politicians are caught taking money from GE. Landslide victory for the Dems. All because of a misguided concept that only left wingers can get ticked off by the stupidity and greed that led to this Mark I problem.


  247. Quoting Patrick Niessen:

    – A reactor is build on a coast with a large and well documented Tsunami Risk

    – Reactors all over Japan are built on or near active Earth Quake fault lines

    – They are operated by a company well known for falsifying safety reports, circumventing regulations and building codes, engaging in suicidal processing techniques and intentionally hiding facts or lying

    – The plants are supervised by an agency that fully relies on the operator to take measurements, fix faults, etc

    – All things that were earlier said cannot happen actually did occur

    – International experts are flabbergasted by the official statements coming from Japan

    Engineering Hubris – I recommend reading Homo Faber to remind people the role of chance (or even fate), if this is required after the financial crisis and the Oil Disaster in the Gulf of Mexico.


  248. This is not directly tied to the event in Japan or any other reactor “accidents” but could anyone tell me how we store nuclear waste or the containment vessels of a reactor after decommissioning? What has the cost of this issue been to date? This is never added to or discussed when considering the building of a new reactor. Reactor construction has always cost two to three times as much as the estimate so I feel sometimes the people promoting nuclear have more important issues of profit than civic responsibility. As far as accidents go there have been far more than the A.E.C. or its’ replacements would like for one to believe. While these accidents are not directly involved with the operation of power plants it does involve nuclear research and testing*. The designs are old and the repeated “it won’t happen again” always comes into play. If a coal mine is hit by a quake the loss of human life and economy could be great but it doesn’t carry on for 300 plus years or possibly a millennium of dead land. People say solar can’t support the all planets energy needs. I believe this, but can’t, never could. If you don’t believe technology can bring solar on line then you can’t convince me that nuclear power from its beginning refinement to deposal is a safe and economical endeavor.


  249. albert, that post is not from Mr Brook but from a Josef Oehmen (read the beginning). A lot of the information and assessments it provides are incorrect or have been superceeded by events happened in the meantime.


  250. Dear Coalburner. Two comments
    1) There is a risk to everything we do, of course. Everything has a finite likelihood and consequence. (You wear a seatbelt for safety in the car as you chose to drive, but if you wanted people to drive slower and with more care you would put a spike in the centre of the steering wheel, but I digress) We do not build ships with 10+ hulls to protect against icebergs, we do not wear body armour when going to the store etc. This is because we make a judgement between the liklihood of something happening and the cost (money, time, other inconveniences). Simply being deterministic in your approach to avoid a theoretical worst case scenario, would mean nothing ever was done, anywhere. Of course, where you “draw the line” is often subjective and based on experts decision (who we hope are impartial and well informed, of course). Where this line is drawn is something to discuss, but it must be drawn somewhere

    2) Whether these particular plant designs should have been operating is a question for the Japanese nuclear regulator authorites who gave the site a license – and, despite the low risk of a Tsunami in Switzerland, ENSI who license the similar plant at Leibstadt and other such bodies elsewhere.

    Some really smart comments on this site, thansk BNC.


  251. Our Prime Minister in the UK came up with a statement that I partly agree with. Basically he is saying that we should not jump to conclusion regarding the nuclear incident, however he continues to say that they will have to consult our advisers. Now call me cynical, but if the short term economic/political case for nuclear is in the interest of the government, would it not be convenient to have the experts come back with a pro-nuclear conclusion. It has happened many times in other fields. I laugh because some of the experts on the illegal drug committee were fired when they did not agree with the governments policy.


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  255. Johnny English,

    No. In this case. No. And where so many lives are at stake, you can’t compare it to one person’s assessment of risk when driving.

    It’s this attitude that gives us these preventable catastrophes (Gulf Oil Spill, etc).

    There was no excuse for not being prepared for a 9.0 in that region and no excuse for having the pumps in an area that could get swamped. Keeping a Mark I going so long except as a cash cow for shareholders to see more profit in 2010. Reactor 1 was supposed to go offline permanently on March 25th. For the rest of the world’s Mark I’s you will now see retirement a lot sooner.

    That depleted uranium site is so badly wrong in its attitude by the way. If you are here from there, note that it is NOT a good idea to take a no prisoners, non apologetic approach such as never admitting that nuclear energy isn’t dangerous, etc.

    The best argument for the pro-nuke crowd is that the left wingers have prevented the replacement of the old Mark I’s with newer plants. That argument will fly, possibly.


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  257. Thanks very much for this.

    I currently reside in Chiba and I am in a very lightly but still affected area of the quake/tsunamis.

    I am essentially fluent in Japanese having lived here 4 years and studied vigorously, and I can tell you that there have been many contradictory reports on TV indeed. Also, a severe lack of practical information such as you have kindly provided above. It has been said that:

    – a melted core could in fact break through all containment barriers and burn itself into the Earths crust like an ember through paper. (My own analogy but, you get the picture)

    No mention of:
    – the strength of the 3rd containment vessel or composition of the 2ndary vessel has been made. The working assumption here is that the fuel inside can just burn its way through anything indefinitely and also do so very quickly, again like an ember sitting on paper.

    – (brief) mention only, and only in the very initial news pieces not at all anymore, of the control rods and main nuclear reaction having been stopped. It is most likely a working assumption in most peoples minds that the main nuclear reaction, the ‘main oven fires’ are still burning away in there, or something.

    – there has been sufficient mention of how low radiation levels actually are, but nothing about half-lives. Knowing most of the radioactive material which is being released dies within seconds would be of great relief to many people (if theyd just friggin report it!)

    Add to this cultural aspects such as

    – The Japanese hate saying the wrong thing and rather than say something thats 99% true they prefer to wait till its proven 100% true, have a meeting about it and so on. This leads to

    – a lot of use of the volitional form, the ‘most likely’s, the ‘maybe’s and ‘mights’ and ‘one could possibly say’ etc, to the point where you really feel you cant trust the info.

    Take all of the above and you have a really well controlled but bitterly panic-inducing situation.

    Thanks again for the post, good to know Chernobyl is impossible in Fukushima and that even a slow meltdown is of no immediate risk.


  258. yes….this whole situation was ‘impossible’ before it happened and now it happened and it seems pretty possible. who knows which other impossiblities come possible in no time.

    it is good that other countries (especially in the EU) think over their nuclear-concepts.

    i am sorry for all the japanese people. i am a big fan of many stuff their culture brought to us. it is hurting me that they to go through all this…at the same time.


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  260. in other countries the people just raise their voice right now! when if not now?

    i am pretty sure that if the people of japan would have been told clearly …listen, we build nuke plants which are technically not perfect and they will be in an area where we should actually not build them…. maybe i am wrong, but i bet they would have tried to avoid that.

    and if not, it is still absolutely legitimate for the rest of the world to raise their voice now and try to stop this nuclear insanity.

    why are we not allowed to learn a lesson?
    who wants us not to learn?
    this is the question.


  261. The key sentence in that article is “The third containment is designed, built and tested for one single purpose: To contain, indefinitely, a complete core meltdown”.

    Two problems with that:

    1) As we know, not everything is “working as designed” here, so that would be a huge bet to take.

    2) It’s not even true… This has never, EVER been “tested” for a true meltdown. There have been computer simulations, and some small-scale regressions tests… but this was never tested for a full meltdown.


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  264. exactly. the problem with this article is that the writer describes this particular power plant as if he has been in there.

    as we know now:
    some of the parts are even missing in the plant built by Toshiba.


  265. There’s a small error in your Richter Scale calculation. The difference in energy between a 8.9 earthquake and a 8.2 earthquake is not 7; it’s 11. Each number on the scale indicates 31 times more energy (logarithmically, as you indicated). So 31^0.7 = 11


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  267. Ironically, the backup diesels were the weakest link in the chain, and the ones that could have been the easiest to retrofit to prevent.

    Since the facility was built, much has been learned about the science of tsunami waves, such as that earthquake-spawned tsunami top out around 10-12 meters. Similar limits also tend to apply to typhoon storm surges (another sea phenomenon that has been researched much better since 1970).

    There were probably 6 or more chances (the refueling maintenance periods) where someone could (and probably should) have looked at the elevation of the generators, and relocated them to a purpose-built mound to raise them to 15-20 meters above the surrounding landscape, and into an armored, sealed building protected by berms and battery-powered pumps.

    It’s probable that the control rooms had similar protection, from their heights in the surrounding buildings – why the equipment meant to be used from the control rooms in a reactor emergency was not given similar protection will probably result in a lot of finger-pointing and plant modifications.

    When it comes to safety, it’s better to overengineer because nature (and the occasional terrorist) have repeatedly proven that “worst-case scenarios” typically aren’t.


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  269. They should have had power switchover boxes rigged with the correct male and female plugs for any needed aux gen sets with the proper attachment tools at the ready…even Homer Simpson could figure this one. Doh!


  270. Mr. Brook, you also seem to assume that the control rods were successfully inserted immediately after the earthquake began.  How do you know this?

    If the rods were not inserted all the way, then (of course) there *is* an issue with continuing criticality, and your analysis is fatally flawed.


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  273. Lisa, continued criticality is impossible even if control rods were not inserted, due to the boric acid in the coolant water. And since these are water moderated reactors, criticality is ALSO impossible if they dry out and there is no water at all.

    The only time a reactor design like this can be critical is when control rods are out, AND it’s swimming in water that hasn’t been treated with neutron poison.


  274. According to wikipedia the No.1 reactor was commissioned in 1971 with construction starting in 1966. Does anyone know how old the DESIGN of this reactor is? I’m don’t know how the permitting process worked in Japan in the ’60s, but here in the U.S. the lengthy process would seem to indicate a design dating to the mid ’50s. Are the failures of such outdated technology really pertinent to the discussion of the safety of current designs? A second thought: It seems to me that the failure was not of the reactor design (outdated as it was), rather the failure was in the backup emergency power supply provisions. This is a separate issue from the safety of the reactor itself.


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  278. They have partial meltdown in reactor 2, possibly in 1 and 3 as well. They have only one functional pump and three reactors with broken cooling systems, so they have to choose which is the most dangerous at any given point in time, when really all three need to be cooled constantly. They need to keep pumping in sea water, which keeps running the risk of hydrogen explosions, any one of which could compromise the core, which would be bad news. If it was the #3 reactor, that would mean plutonium being released. I’m basing this entirely on govt. and industry statements. So you can see how far off base Dr. Oehmen is.


  279. To those who are ignorant of the Russian designed unit at Chernobyl:

    There was NO containment vessel constructed around the reactor. The Russians did not believe them necessary. Thus the problem with magma-like radioactive material spewing forth from the bowels of the reactor.
    The only option after the failure was the construction of a concrete ‘sarcophagus” poured over the reactor in a huge pile. Said covering is deteriorating rapidly and a more permanent solution is supposedly under study.


  280. I’d like to be as sanguine as all the experts, but all that’s been documented here is a brave prognostication in a “if everything works as designed” sense. However, since no one posting here is actually there, and because the IAEA has just dispatched a team to Japan, I don’t think anyone here posting knows anything more than what you are hearing or reading in the press.

    TEPCO has an abysmal safety record and you can’t trust Japanese officials as far as you can throw them. Since the second day after the quake/tsunami, the official version of things has been that they are getting everything under control. I guess that’s why the outer containment building for another reactor blew its roof off today.

    I’ve got a vested interest in this having a happy ending. The last thing we need right now are pro-nuclear experts explaining how what’s happened to date is nothing to worry about and that three reactors reaching critical state isn’t anything to worry about.


  281. Hello I have read the article carefully but have some (sorry if naive) questions:
    – “The third containment is a hermetically (air tight) sealed, very thick bubble of the strongest steel” so how is the pressure released from that? Are the valves that you mention installed on the third containment?
    – What about the people who were found to be infected by radioactivity? From your article I would expect that nobody is harmed.
    Thanks in advance


  282. You mention that the H2 accumulation was the result of venting primary containment (Drywell) to secondary containment (Rx Bld). Why not go to the Stack using Stand By Gas Treatment (SBGT). Was this out of service due to loss of Safety Related electrical from EDG?

    Perhaps change to MARK 1 Containment with a manual vent to atmosphere on the refuel floor to vent H2 on station blackout.


  283. it is like someone posting the user manual for a car which has been already driven against the wall and manual mentioned airbags, but they sparsed out the airbags because….well, stuff like this is so expensive..


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  287. This event worries me in the sense that it will be a roadblock in the research and development of better nuclear reactors. I am a layman but I realize the importance of nuclear reactors to sustain our way of living, our energy needs seem to have an exponential growth and there is no way we can achieve this using wind and solar.

    I am not against wind, solar and hydro-electric power; I just don’t see a way we can maintain the necessary energy output without having nuclear power to provide a solid base that we can complement with renewable sources.

    The biggest threat as I see it today is our coal/oil plants that directly contribute to greenhouse gases and frankly should be scrapped a.s.a.p.

    As for all you pro-wind people, why is it that we can’t build wind power? There is always harsh resistance, mostly from the green-people, citing destruction of nature, killing of birds, reflections causing epilepsy, horrible sound and em-radiation. Now these are things that are preventing the construction of wind power in my home country Finland, I find most of them bogus, but somehow they have effectively halted the development.

    I support all additional power sources as I think that humanity needs endless power to achieve our potential.


  288. Something that has been forgotten in this is that even though Caesium 137 DOES react with water in a harmless way (besides the exploding part.)…

    They are radioactive! It doesn’t matter what reaction occurs the half-life of 30 years still stands. Radioactive elements remain radioactive and carry radioactivity beyond any normal reaction with an element like water.

    Caesium 135 will stay radioactive for millions of years.

    It isn’t the isotopes reaction to outside elements that matters, it is the radioactivity. This radioactivity was detected on American Fighter Jet pilots hundreds of kilometers away when they returned to aircraft carriers. The original 12 mile zone was really a hundred kilometers plus.

    Although Dr Josef Oehmen gives a good analysis, it isn’t complete and the facts are only given on information that has been released. We always find out later that things aren’t often as they first appeared and the truth is somewhere in the middle.

    Many scientists other than Dr Josef Oehmen are expressing great worry, he is saying don’t worry.

    We DO KNOW Caesium HAS been released.

    That leaves the truth to be something to take note of.


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  291. Some help;

    lschubert – The containment may not have been tested but similar ones have such as 3 mile island. It is also HUGELY over engineered. They work out how big it has to be to contain the fuel in this situation (using simulations) then they make it MUCH bigger and stronger than it needs to be.

    armchairpilot – Ceasium isn’t the real issue iodine is. Because such small amounts have been released the only danger is if the material is ingested or inhailed and accumulates. Ceasium will not accumulate, but spread out. Iodine will accumulate in parts of the body so it is an issue. However the iodine half life is very short so will almost be gone!

    Emery – MOX fuel is only different as it contains 3% Plutonium. The other cores at this stage in their lives will have ~1% Pu due to neutron capture in uranium (called breeding). So they all contain Plutonium, which isn’t any worse. If anything Plutonim is more mechanically and thermally stable.

    I have missed a lot of other questions but please feel free to email me about anything you’re interested in. The media has over egsadurated a lot, and paraphrased very inappropriately:


  292. It will be fascinating to find out which side is right in this argument. Two quite opposite opinions battling over what is really the situation. We should find out soon enough.


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  295. Thanks for the enlightening article.

    I am sure there were good reasons to do so, but I am puzzled why a BWR which doesn’t need seawater to run, is built so close to the ocean, facing a known subduction zone.

    As a layman, I would recommend NOT building any future BWRs on the coast, but inland, just a few tens of Km. And implement a minimum height above mean sea level (say 30-40m). I noted other suggestions that they be moved to the West coast, but that is far from the centres of population. I think there is a happy compromise which, yes, may require extending the high tension power lines to the new area in the foothills, but certainly seems like a safer option going forward.

    And the story about the power plugs not fitting? You can’t be serious! Any competent electrical engineer could resolve this issue. I’m going to spend the rest of the day trawling through the news reports to try to get a better understanding of the precise issue. It just can’t be as simple as stated.

    I am a nuclear, wind and solar proponent.


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  297. After working in the media myself and being a bit educated about the distance to which some (all?) media trusts would go to sell their material and drive the general attention upon it, I have to say that I trust this article to be a lot more accurate and transparent than the general mambo jumbo you’ve been seeing on the news lately. Why I choose to believe this ? Because i’ve spent the last 10 minutes reading hard facts as opposed to the televisions that have been feeding one overexaggerated scenario after the other to the general (sorry to say this but it’s true) uneducated population – I mean c’mon, how many of us are actually nuclear scientists and can pick the truth apart from the little white lies? Thank you for a great and educated explanation Mr. Brook.


  298. @m from previous discussion: i would like to remind you that your “clear, brutal facts” come from biased sources as well. You have no idea if its actually 200,000 people. Every source is biased. There’s no point in arguing until whatever happen’s happens.


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  300. What I don’t get is this – and it’s probably simple to some people, but I’m no nuclear engineer. If the rods can’t be cooled and continue to heat, and they melt, what happens next?

    These fuel pellets have a high melting point of 2200 degrees. Steel melts at approx 1370 degrees. The base of the containment is concrete and might well have been subject to damage from the earthquake. Zircaloy melts at 1850 degrees, which will not contain the fuel or the melting rods.

    I can’t see how this can be contained unless they can be cooled properly. if the fuel and the rods melt. I think we’re heading for a disaster much bigger than Chernobyl.

    . My heart goes out to all the people of Japan – especially those sacrificing their lives to avoid major catastrophe in the nuclear power plant.


  301. You make an error in math. An 8.9 is only about 5 times larger than an 8.2 in log scale.



    The zirconium melting disassociates the water into H and O so that would imply temps above 2200 celsius.

    If, as you say, the uranium oxide is in pellet form, wouldn’t they fall to the bottom of the second containment. Because the first containment has melted away. If they get clumped up at the bottom pressure cooker aren’t they more likely to go supercrit, runaway on the engineer so adding water instantly boils off?


  302. We can be thankful that public concern over reactor safety is actually a very positive thing in that over the years it has required the nuclear industry to implement stringent safeguards and (as is now being demonstrated) these safeguards are indeed warranted.

    So a heartfelt thanks to all those who have been a part of these advances, pro and anti nuclear folk alike.

    Some within the nuclear industry have no doubt resented such safety advances because they have contributed to a prohibitive cost of nuclear power construction rendering that technology less cost competitive than other energy sources. But just imagine for a moment if those standards had not been developed as they have.

    Actually, we don’t have to imagine, we know what happened with BPs rig in the Gulf of Mexico – deep sea drilling for oil had no rigourous safety regulations in place and in the aftermath of that debacle the nuclear industry was cited as a prime example where regulations had been forced on an industry as a result of public concern.

    The Fukushima incident will be very helpful in the research and development of safer nuclear reactor technology. It was fortuitous in a way that this incident happened within a jurisdiction that has the technical capacity and resources to handle the emergency, just imagine if this same event was occurring right now in earthquake-prone Indonesia.


  303. If they get clumped up at the bottom pressure cooker aren’t they more likely to go supercrit

    No, subcritical. Criticality or supercriticality, with low-enriched our unenriched fuel, requires that the neutrons leave the fuel for a while, and travel through a moderator, e.g. water, and then return to fuel.

    So fuel lumps spread out through moderator can be going along in that state, and then, if they fall together, they are extinguished by the absence of moderator in between.


  304. errors and errors too by the end not limited to:
    “because the Uranium decay was stopped a long time ago”

    wording denies law of physics if I understand the translation correctly. halflife of the the active isotopes. the decay is still present at some levels due to halflife but there is high chance all the particles that can activate another uranium atom are trapped by the control rod. so the ratio of decaying:newly activated is

    if the “likely to happen” condition far above in the text is true then probably the more correct wording should be: stopped the excessive activation among different fuel rods (continues in the rod itself ? lot less heat produced but still some? slowing down the decay of uranium closer to the levels of extremely small quantities in ratio to the mass in the reactor.

    i’m no hightech. but that last part sounded ridiculous. so did I got at least a closer to the perfection this part?


  305. Chris:

    The Fukushima incident will be very helpful in the research and development of safer nuclear reactor technology.

    AFAIK, there was nothing wrong with the reactors in Fukushima. The one and only cause for troubles seems to be the diesel generators that couldn’t withstand the tsunami.

    That’s obviously a design failure, or risk management failure or something. And it’s a shame, a VERY BIG SHAME, and I’m sure we will hear more about this in near future.


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  307. Amateur idea: Could a number of pressure vessels in series with a reserve of stored water be used to recycle steam like a massive distillation apparatus until such time as the core residual heat begins to fall? I suppose that redundancy would be too expensive even if it was theoretically possible.


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  309. It is nothing new that the media targets the “mass” or “corporate slaves” or the “unfortunates” to cause panic, fear, anxiety and curiosity as well as “the lust to see some action”. I particularly enjoy the facial expressions some journalists are required to have and use while recounting certain events (which is the reason you always see the same people telling the news). People are being influenced to watch more, to keep the channel on, all to benefit the news broadcaster, or at least, the owner of it. Unfortunately the wrong people like Murdoc and Co will now become richer, due to the already general mass population watching this now for hours a day.
    I totally agree with person that wrote this article with how a nuclear powerplant functions and that it cannot explode and that it cannot turn into a next Chenorbyl. I do not comment on the calculations as I am ignorant in regards to advanced mathematics and physics, but the fact is, it will not turn into a dirty nuclear bomb and spray around crop, farm animals, people which then pass the radiation on to anyone else they just get close to.

    I would also like to add that now is no time for a mathematics competition nor a who is wiser than the author. I am sure that the author of this needed to write something as fast as possible since every second counts before more people become infected from the news virus, so therefore errors in any regards such as calculations or exact decaying times, even if it takes 30 years instead of 30 seconds for now are tolerated. Because much worse is people being infected by the news virus that go around spread their ignorant viewpoints as recalled from Fox News and CNN.

    Propaganda and news broadcasts are after all a weapon of mass desctruction much greater than what is happening in that plant right now so I thank the author for his time in diverting people off those horrible news virus producers that are cashing in big time by the second.


  310. In his summary Josef says

    “A very small amount of Cesium was released, as well as Iodine. . . . . . The Cesium and Iodine isotopes were carried out to the sea and will never be seen again.”

    This is a highly inaccurate and misleading description. Radioactive Iodine -131, after it is breathed or injested, immediately accumulates in the thyroid gland. Its radioactivity decreases about 8% per day, so that after 2 weeks there is still 31% of the radioactivity present. If the initial level were one million times the safe amount, 2 weeks later there would still be 300 thousands times the safe amount.

    Cesium-137 has a half life of 30 years which means that its radioactivity decreases only by about 2% per year. It is water soluble and is absorbed by vapor in rain clouds from where it can be blown anywhere and deposited on large areas of vegetables and on grass which animals eat. This leads to the supply of radioactively contaminated food and especially milk and meat products.

    Josef’s post is an insidious example of deliberate disinformation used in “crisis management”, which as it happens, is an area in which Josef is an expert, as shown by his publication list at



  311. I’m japanese, and I read “version 2 (in Japanese. by Shota Yamanaka)” and I have a question.

    > By the time you spelled “R-A-D-I-O-N-U-C-L-I-D-E”, they will be harmless, because they will have split up into non radioactive elements

    If it’s true, better news for Japanese.
    But, when the first reactor building explosion, 90 people were outside.
    They were in the place where was 4km distant from nuclear power generation, but three people did radiation exposure of the quantity that decontaminating it needed.
    (I thought that the all the members who were in the place may have been exposed to radiation, but the Japanese Government chose only three people and inspected them and announced it with which “3 people got radiation”……)

    Is it that the thing which should disappear in several seconds moved 4KM during the several seconds in your sentence?
    Or will the thing discharged in this accident be different from radioactive material in your explanation in a kind?

    I am anti nuclear power generation. However, it is good news to let people suffered from relieve if radioactivity leaking in this accident is safe.
    But neither the Japanese Government nor the expert mentions it at all.
    I don’t wish Japan becomes the panic. However, I believe that I am reliable and don’t wish the damage becomes serious more.

    Sorry about my poor English…
    I expect that there is a clear answer from you.
    Thank you.


  312. Pragmatist, your own link describes him as a Research Scientist and he certainly has a PhD. Rather than an economist, I’d say he is a business systems engineer. Still not a nuclear scientist of course, but a technical background and interest in the area is often a better precursor for a popular article than a deep technical knowledge.


  313. I only hope the assertions of the author of the article (a research scientist at MIT Boston whose father has extensive experience with the German nuclear industry), are correct and that the ‘final-line-of-defense containment’ in these reactors has remained uncompromised as intended.

    Its fair to say that (at least in my opinion) when we get to the ‘final line of defense’ in a nuclear accident with six, possible more individual reactors in full crisis mode simultaneously, that there is reason to be concerned whether that ‘final-line-of-defense’ in each of those reactors will hold up as intended. Each Japanese nuclear ‘plant’ has as many as 5-6 ‘reactors’ in each plant.

    It would appear that no less than ‘four more reactors’ in various plants will be allowed to reach ‘the final line of defense’ in full fail mode — because of inoperative primary cooling systems, secondary cooling systems, emergency diesel back-up cooling systems,and, last but not least — hastily installed (but inadequate) mobile diesel cooling systems.

    At this point they are resorting to pumping in sea water (the cooling measure of absolutely last resort…it has never been done before) to prevent the core getting so hot it could possibly compromise the final containment tomb. That seems like it would work so I’m somewhat comforted. That’s what the explosions are you see on television — when sea water meets near molten reactor core the hydrogen and oxygen in water separate.The pressure has to go somewhere. The so called hydrogen explosion. A giant pressure release. They claim they are controlling that. I’ll play along. I want to believe. But my skeptic keeps poking me. I wish he would stop.

    Seawater however destroys the reactor as an asset. It can never be used to generate power again. In other words they are flirting with meltdown up to the very last minute in an attempt to salvage an asset (admittedly a needed public utility too. Its freezing in Japan right now on top of everything else they’ve endured. It’s a full blown apocalypse for the fine people of Japan.) We must trust that they know best when to start pumping in seawater and abandon trying to save a capital asset. Nuclear brinkmanship of a different order. They are balancing on the head of a pin. A lot of Japanese national pride hangs in the balance. Wish them good luck and pass it on.They could use some good luck right now.

    In other words we need to have faith that highly unstable and dangerous near molten radioactive material in borderline meltdown mode will be ‘contained’ by the final line of defense — basically a very large concrete tomb and that the operators will know the precise moment when to give up on saving the reactor and throw the seawater in there to slow old Nuclear Nelly down. I wont even tell you about the failed gauge at Reactor #1 that prevented them from knowing the actual core temp — so I’m assuming they used their best guesstimate when to start pumping in the seawater. Pray for the integrity of that concrete tomb. Four more containment tombs have to survive their first (and only) test too in the coming days. Again I am only assuming that the first two have. Pray that I am right. Prayer actually could make a difference now.


  314. Very good and informative article.
    As an Iranian, with all my peace and love please accept my excuse if I couldn’t answer the question regarding the difficulty of building a nuclear bomb.


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  316. The cold, hard, inescapable fact remains: THERE WAS NO CATASTROPHE. Those powerplants were hit by one of the most powerful earthquakes in human history (an earthquake several times more powerful than they were built to withstand), AND they were hit within an hour by one of the most powerful tsunamis ever seen. They were clobbered by a one-two combination of historic proportions, and despite that, THERE WAS NO MELTDOWN.


  317. High res.satellite pic of Fukushima Daiichi plant with Reactor #1 to the bottom and reactor #3 to the top. Photo taken 3 minutes after the explosion. Email me for pic if Flickr is down.


    Similar photo of Chernobyl reactor block after explosion. I’m sorry but Reactor #3 looks to be in much worse shape than Reactor #1 after their respective explosions. Secondary containment is visible above Reactor #1. Not so clear if it is above Reactor #3.


    if you have trouble accessing email me and I will forward both pics for you.


  318. I am sure Dr Josef Oehmen had the best intentions while writing this, but it clearly doesn’t stand. Too many assumptions are made.
    That the government actually reveals all information in a correct manner.
    That operators are performing correctly (meaning following the book).
    That the construction of the reactor is as described.

    Any of those assumptions might be easily ill-founded. Clearly there is not enough information as to what is happening at the site. Different sources give different information, France even put the incident higher on the scale. While the western media certainly goes over the top, in Japan not much is said by the government. As an example, the Toshiba containment vessel designer said that they have no idea if the containment vessels are completely intact for sure, that some of the monitors might not display correct information etc.

    Also, many points of the article are already disproved. The author clearly stated that there is no danger even if one must sit on top of the reactor. That doesn’t fit with evacuating 200 000 people (evacuation which in itself is dangerous and may cost lives) and screening some for radiation. Or US troops measuring elevated levels kilometers away from the site. Or Japan calling for help from US.

    The article also doesn’t take in account what aftershocks can do to that situation (there’s still one 7 forecasted with 70% chance), tired operators and whatnot.

    This surely isn’t going to be a Chernobyl, no doubt about that. But it is also only 270km away from 12 million people.


  319. @Greg Brede

    In the original Mark-I design, the suppression pool was believed to sufficiently relieve steam pressure. But:

    “In 1986, Harold Denton, then the NRC’s top safety official, told an industry trade group that the “Mark I containment, especially being smaller with lower design pressure, in spite of the suppression pool, […] you’ll find something like a 90% probability of that containment failing.” In order to protect the Mark I containment from a total rupture it was determined necessary to vent any high pressure buildup. As a result, an industry workgroup designed and installed the “direct torus vent system” at all Mark I reactors. […] the vent is a reinforced pipe installed in the torus and designed to release radioactive high pressure steam generated in a severe accident by allowing the unfiltered release directly to the atmosphere through the 300 foot vent stack.”

    Filtering should be of minor priority under accident conditions. Either the steam was already in the containment, the venting system failed, or it was never retrofitted to the reactor in question at all. Also see this 1987 article I have linked to repeatedly over the last days, that describes what happens after containment venting (release into reactor building) and seems to have been written before the “direct torus vent system” was developed:


  320. “an earthquake several times more powerful than they were built to withstand” – Keith

    Which raises the question: why were they not built to withstand more powerful quakes and larger tsunamis? This was a large earthquake, but far from unprecedented: the Chilean quake of 22 May 1960 was a 9.5.

    BTW, Keith, the earthquake and the tsunami were not unconnected, so to call this a “one-two” as if they were two independent events is daft.


  321. @Keith Loosing cooling on a nuclear is already a catastrophe. Hence the coverage you see.

    “There was no meltdown”, even if written in capitals is still not a fact, but merely an assumption. And given recent news, the safer assumption would be that there was partial meltdown.


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  324. You note that it wasn’t stated if the sea-water was being pumped inside the ‘pressure cooker’ or outside, IE a water bath. That they are putting boric acid in the water seems to strongly imply that it is going inside along with the fuel rods to help inhibit the reaction inside the chamber. They may also be flooding both.


  325. @Greg Brede

    sorry, I misunderstood your question – thought you were asking about the torus vent system.
    As of SBGT, some speculation: it may not have been installed at all (patent application from 4 years after Unit 1 went into production [1]), it was not designed to the pressure developed, it was installed but connected to the annular [2] – in which case the idea may have been to vent via SBGT, but the hydrogen exploded before that could happen.

    [1] http://www.freepatentsonline.com/3925046.pdf
    [2] http://tinyurl.com/5u58xk8


  326. @Josh

    AFAIK, it has been pumped inside the “pressure cooker” only.

    @Greg Brede

    sorry, I misunderstood your question – thought you were asking about the torus vent system.
    As of SBGT, some speculation: it may not have been installed at all (patent application from 4 years after Unit 1 went into production [1]), it was not designed to the pressure developed, it was installed but connected to the annular [2] – in which case the idea may have been to vent via SBGT, but the hydrogen exploded before that could happen.

    [1] http://www.freepatentsonline.com/3925046.pdf
    [2] http://tinyurl.com/5u58xk8


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  328. I just found this discussion using Google, and a quick search indicated the corrosion properties of zirconium (Zircaloy-2) used in fuel cladding in this reactor have not been discussed and are a critical part of the failure sequence. SinceI personally did some of the pioneering work on Zircaloy-2 for eight years back in the 1957-1965 while working as a materials scientist for GE).let me add the following to an otherwise excellent review of this accident:

    I believe there is a close similarity to what is now going on in Japan to the Three Mile Island accident. At Three Mile Island a combination of equipment failure and operator error caused the water level in the pressure vessel to fall and expose the very hot fuel to just a steam atmosphere after the reactor shutdown. This lead to overheating of the zirconium alloy fuel cladding, which then begins to corrode rapidly in the hot steam forming a hydrogen bubble at Three Mile Island with this quote the Wikpedia article on the TMI accident::

    “After almost 80 minutes of slow temperature rise, the primary loop pumps began to cavitate as steam, rather than water, began to pass through them. The pumps were shut down, and it was believed that natural circulation would continue the water movement. Steam in the system prevented flow through the core, and as the water stopped circulating it was converted to steam in increasing amounts. About 130 minutes after the first malfunction, the top of the reactor core was exposed and the intense heat caused a reaction to occur between the steam forming in the reactor core and the Zircaloy nuclear fuel rod cladding, yielding zirconium dioxide, hydrogen, and additional heat. This fiery reaction burned off the nuclear fuel rod cladding, the hot plume of reacting steam and zirconium damaged the fuel pellets which released more radioactivity to the reactor coolant and produced hydrogen gas that is believed to have caused a small explosion in the containment building later that afternoon.”

    This same lack of cooling due to the failure of the last battery powered safety cooling system appears to have exposed the fuel rods in a similar manner in this Japan nuclear accident. The media is calling this a “meltdown” which is a misleading, but commonly used term. What actually happens is the normal corrosion reaction of zirconium exposed to water or steam rapidly accelerates as the cladding temperature rises without cooling water.

    Zr + 2 H2O = ZrO2 +2 H2

    Zirconium is an extremely reactive metal, but this reaction quickly forms a corrosion resistant thin film of ZrO2 that almost totally blocks the reaction from proceeding in normal temperature reactor conditions. In fact it is routine to autoclave fuel rods to pre-coat them with this thin film. However if overheated, this reaction takes off exponentially, the coating becomes thick and cracks, hydrogen is absorbed into the cladding causing embrittlement, and very quickly the protective cladding cracks and releases fission products to the system. Radioactive cesium and iodine detected are clear evidence of cladding failure. If this reaction proceeds far enough the cladding can crack off causing uranium oxide fuel pellets to be exposed or even drop out of the fuel assembly into the bottom of the pressure vessel.

    So rather than “meltdown” a more accurate description is: “catastrophic fuel assembly disintegration”.

    This process can be stopped by getting cooling water into the vessel which is what the Japanese are doing by pumping in sea water. Putting boron compounds in the water, which are strong neutron absorbers, guarantees that in a worst case scenario, a pile of fuel pellets in the bottom of the vessel cannot go critical and restart the nuclear chain reaction.

    Clearly after seawater containing chlorides has been put into the reactor, it will NEVER run again, since chlorides cause stress corrosion cracking in the stainless steel used for the pressure vessel and piping and one could never get all traces of chlorides removed again. I DO worry about stress corrosion cracking of the stainless steel pressure vessel and piping which can cause cracking failure in boiling seawater.

    The hydrogen explosion occurred just as the operators were starting to put water into the vessel which probably vented the steam containing hydrogen into the building where it exploded. An explosion this big implies that a LOT of zirconium fuel cladding has been destroyed by reaction with the steam in the pressure vessel. But, that is why this huge pressure vessel is part of the safety system- it keeps all the debris and fission products inside when sealed. However, it will be a huge financial cost to decommission and disassemble it!

    It is ironic that this reactor is 40 years old and I read it was scheduled for shutdown this year .

    This scenario is nothing like Chernobyl where a steam explosion blew apart the graphite moderator and building ( there was no containment building) letting air in. This caused the graphite to burn up the fuel elements in a catastrophic fire spreading the fission products over thousands of miles for days. This CANNOT happen in the reactors in trouble in Japan as they have NO graphite moderator.

    I hope this clarification is useful.


  329. Chris, does the “he” refer to me?

    I can assure you I am a scientist. Bachelor Degree-Rice University 1955, Master’s Univ Texas 1956 and a card carrying member of the National Association of Corrosion Engineers for decades. I retired in 1995

    I don’t know the guy in your post


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  336. PacificNW Don wrote: “I DO worry about stress corrosion cracking of the stainless steel pressure vessel and piping which can cause cracking failure in boiling seawater.”

    Has this just happened with #2 Reactor? There was a different sort of explosion, and the containment vessel is reported as losing pressure, so either liquid or gas must be leaking out somewhere..


  337. from the guardian blog update.

    11.22pm: A rupture may have occurred inside the containment vessel at Fukushima’s number two reactor, Japan’s NHK public broadcaster is reporting.

    Although details are only slowly emerging about the explosion that was heard there a short time ago, technicians have been told to evacuate the area

    A nuclear expert told the broadcaster that there may have been a radioactive leak as a result of the explosion at the vessel, which is supposed to prevent radiation from leaking out.

    The explosion appears to be related to a fault with the suppression pool at the very bottom of the containment vessel. Steam is brought down to the pool and is used to cool the reactor.


  338. As much as the above makes sense, it does make the assumption that there has been no damage to the containment building, and that no further damage will occur.

    Meanwhile, we seem to have TEPCO managing to generate daily explosions on site. The latest sounds much more worrying than the last couple. From the BBC’s live update site at the end of March 14th (JST):

    2344: Tokyo Electric says that 50 employees are still staying at the Fukushima plant

    2340: Tokyo Electric officials are now holding a news briefing. They say the blast at reactor 2 happened “near the pressure vessel”. They also confirm that some staff at the nuclear power plant are being evacuated.

    2333: More details on the reported blast at Fukushima’s reactor 2. The explosion is feared to have damaged the reactor’s pressure-suppression system, Kyodo says. It adds that “radiation tops legal limit” after the explosion.

    2320: A spokesperson from Tokyo Electric says said some staff have been evacuated from the site.

    2316: Kyodo now says that the suppression pool may have been damaged at the second reactor.


  339. I hope they have enough concrete to seal these off and people willing to get close enough to poor it ..

    Sad to say the last line of ‘defense’ is a rather poor option to have to rely on.


  340. Thanks for the summary Mr. Brook, but I am left to wonder how much is correct. You stated that the fuel is uranium oxide. I read today that in one reactor the fuel is MOX. And I read that MOX is uranium and plutonium. Isn’t Plutonium a more toxic substance? And did you speak to the integrity of the spent fuel storage pools?


  341. Sorry – the above should read end of 15 March (JST). Almost a full day away on the opposite side of the date line here in Hawai’i, and it’s hard to keep dates and times in check…


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  343. During my career as Navy nuclear reactor operator/technician/instructor and professional engineer in chemical, oil, gas, safety system manufacturing, consulting and implementing industry safety system applications, I have observed public perception and reaction to apparent risk of fire, flood, explosions, electrocution, falls, crushing injuries, chemical and radiation exposure. Public fear of potential radiation exposure far exceeds any other hazard risk. They believe death due to radiation exposure is far worst than any other form. Perhaps due to their own personal experience with fire, flood, falls, etc., people understand and can estimate the risk of non-nuclear accidents. But, people do not understand radiation. They do not understand the types of radiation, external and internal exposure, measurement metrics, and its effects. Almost all have been exposed to radiation during physical and dental exams, CAT scans, cardiology catheterization/stent placement, and ingesting radioactive “cocktails,” yet they have no “feel” for the amount of medical and background exposure and how it relates to nuclear facility emissions, so fear abounds. And the media does not help; it reinforces that fear and anxiety. Although the Japan earthquake and tsunami killed thousands (flood, fire, falls) and displaced 100’s of thousands, the media focuses on the potential effects of BWR damage.

    It is in this context that we are witnessing the ongoing third strike against the nuclear power industry. TMI was the first strike. The industry and the regulatory agencies apologized for underestimating the hazards and gave assurance that plant design, operation, training, inspection and scrutiny would preclude this ever happening again.

    Chernobyl was the second strike. The industry and regulatory agencies explained the deficiencies of the RBMK reactor; the superiority of their PWR, BWR and PHWR designs; how the three or four barriers prevent fission product release to environment; how the defense-in-dept concept provides extensive redundancy and fault tolerance; their superior quality control, and training and safety culture. Industry and regulatory agencies touted their calculated probability of core damage frequency exceeding 1 in 100,000 years. That is the equivalent of one core damage event in about 250 years amongst the current population of NPPs.

    And now, strike three. The Fukushima reactors were designed for worst case anticipated earthquake magnitude of 8.2 on the Richter scale, which was exceeded by the actual earthquake. Some say that it is a miracle that the plant withstood the event. The actual tsunami exceeded TEPCO’s worst case estimate, causing a loss of all emergency diesel generator power, which resulted in limited core and no containment (suppression pool) cooling available. Within a few hours, battery power was exhausted and coolant replacement capability was lost. Two, perhaps three, reactors have suffered core damage and a small amount of fission products have escaped into the environment.

    Although one died at Fukushima – not from the earthquake, the tsunami, the explosions, from core damage, nor radiation exposure – we are seeing the death of nuclear industry creditability and trust. Almost every safety assurance principle touted by industry has been violated. Design basis was underestimated. Redundancy and defense-in-depth failed. All fission product barriers failed. It is only because of the courage and resourcefulness of the plant crew that the release is limited. Since it is likely that three reactors suffered irreparable damage, they will be dismantled. And because the other three reactors experienced a beyond design basis earthquake event, TEPCO has lost the entire Fukushima facility.

    So, who will believe and trust the experts and regulatory agencies in the future? Given the previous probability of core damage was so inaccurate, who will believe future predictions? Who will be willing to finance new plants? Who will be willing to insure/underwrite new plants? Regrettably, I fear the trust is lost.


  344. Who pays?
    The whole nuclear industry via increased prices?
    NO! NO! NO!
    The local industry just goes bankrupt
    thus passing the cost onto the taxpayers, and locals while the rest of the nuclear industry quotes cheap power in competition to clean energy


  345. @Troy Martel
    I do not understand radiation. But I would like to know if I am incorrect in these assumptions:
    The effects of radiation in the long term are very difficult to estimate, so very easy to be downplayed in the short one.
    From my limited understanding the situation at Fukushima is pretty serious and can lead to some important leakage. 240km to Tokyo is a small distance.


  346. with the evacuation of the plant, and a further explosion damaging stuff around the reactors, the improvised cooling might not be kept up any longer.

    this will speed up the melting of the cores and it is only a matter of time, until vessels are breached on all 3 reactors.

    i hope evacuation is extended to a much bigger radius, and measures are taken to protect Tokio reason.

    it looks like now our best hope is for a change of wind direction.

    nuclear is not a good technology.


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  349. Well whatever you say there’s obviously a damage somehow in the containment now appeared. High level of radiation in the air ( > 8,000 micro sv / hour) was measured this morning, and the pressure of the suppression pool was down from 3 atm to 1 atm. The durability of containment is not that naively high, said by Dr. Goto the former designing engineer of containment. ( http://www.ustream.tv/recorded/13320454 ) (He mentioned the reason near the end of this press conference why he decided to leave the side of industry to speak up for giving out the truth of vulnerability of the safety system of nuclear power plant system. )


  350. Now here are some corrections:

    1. The Zircaloy fuel rods are NOT a containment layer.

    2. There is no “catch” at the bottom of the containment vessel.

    3. Cesium 137 is NOT a normal byproduct of a nuclear reaction. It is created when the fuel rods overheat, fracture and melt. The presence of Cesium 137 is the result of at least a partial meltdown.

    4. The Boron control rods do not immediately stop the reaction. They only slow neutrons to the point that there is no longer a chain reaction. The fuel continues to fission for quite some time after the rods are inserted. Infact spent fuel will continue to fission for years in cooling ponds, long after they’ve been removed from service.

    5. Residual heat will also persist for years because of the ongoing fission. The venting of radioactive steam will continue for many months at the very least.

    As this piece was written prior to the second and third reactors’ emergencies, I’ll spare the author any further corrections as it would require the use of facts not available to him at the time of his post.


  351. sod wrote:

    “with the evacuation of the plant, and a further explosion damaging stuff around the reactors, the improvised cooling might not be kept up any longer.”

    50 employees are remaining on site to maintain the seawater pumping operation.


  352. When I first read this post I saw it as a breath of fresh air – something to blow away the dense cloud of hype and noise and ignorant speculation generated by the press. After re-reading it I, like others, began to see it as just a ‘little’ too cheery and optimistic.

    At any rate, unfavorable winds are on the way. If there is a large release withing the next day or so, people will be exposed to decidedly non-trivial doses.



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  355. The authoritative style of the article has clearly persuaded a lot of readers they are now getting the truth. Sadly this is not true.

    The elements most likely to migrate out of the fuel pellets, through the damaged cladding and into the containment area and from there into the atmosphere, are the chemically inert radioactive gases Xenon-137 and Krypton-85.

    Xenon-137 has a half-life of 229 seconds and decays into Caesium-137, which has a half-life of 30.17 years , NOT “a few seconds”. It decays 95% into Barium-137, which has a half-life of 153 seconds.

    Krypton-85 has a half-life of 10.76 years, and decays into Rubidium-85, which is non-radioactive. However some 80% of the Krypton-85 from a reactor is in an excited state and its half life is considerably shorter.

    If the fuel starts to melt, many more radioactive species can be liberated. Their chemistry on contact with distilled water is hard enough to describe, but the reactions with dirty seawater just don’t bear thinking about. And anyone who says “its all over” is simply covering up.

    > “Dirt or salt in the water will absorb the neutrons quicker, becoming more radioactive. This has no effect whatsoever on the core – it does not care what it is cooled by.”

    Complete bullshit. The chemistry between the hot fuel and seawater is completely unknown – it might easily make the steel containment chamber brittle.

    > “The Cesium and Iodine isotopes were carried out to the sea and will never be seen again.”

    True, but that is only ‘out of sight and out of mind’. They haven’t disappeared. It is this kind of attitude that leads to disposal of radioactive waste down a deep hole.

    Richter 8.9 is 5 times more than Richter 8.2, not 7 times :
    (10^8.9)/(10^8.2) = 5.01
    (10^9.0)/(10^8.2) = 6.31

    I’m glad the author wasn’t the one doing the maths on the design.

    The big question for Australia is what level of earthquake and tsunami should we build for? This is where the politics comes in, as it is clearly much more expensive to build for a 1 in 10,000 year event than for a 1 in 100 year event. The proponents will always want to cut corners because it increases their profits and if things go wrong they can always go bankrupt and leave the toxic mess in the lap of the government.

    Nuclear reactors are clearly NOT FAIL SAFE – they need complicated technology to be kept running even when they are switched off. Three back-up systems are clearly not enough. Would four have been any better ?


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  358. Does building 55 nuclear reactors to produce 33% of the energy for a great world economy on one of the world’s most active fault lines sound like it may be overly optimistic or delusional? I commend the Japanese for their faith in technology. Still, the quest for cleaner energy has to go on. Nuclear energy is one solution for current energy needs. Yet it is a very unrenewable resource. And it is the overhead of taking care of the bi-products, the collateral damage if you will, that is daunting. We pass this detritus to future generations. Human common sense does not fully comprehend long time scales like Chernobyl’s forecast recovery period. In good times, the issue has always been what do you do with the waste? In bad times it comes down to Murphy’s Law.


  359. Chris Warren, on 15 March 2011 at 11:55 AM — As I stated on another thread devoted to the Fukushima situation, this is a highly focused thread. Please help keep it that way by posting your more general remarks on Open Thread 9. Thank you.


  360. Barry, that was a top-notch summary to calm all the fear-mongers down. Thanks for taking the time to write this up! Hopefully this article will get the widespread coverage it deserves.


  361. David B Benson

    The author wrote “the Richter scale works logarithmically; the difference between the 8.2 that the plants were built for and the 8.9 that happened is 7 times, not 0.7”
    and the Richter scale is base 10.
    The author was not talking about the Moment of magnitude scale, and neither was I.


  362. David B Benson
    The Richter magnitude scale, also known as the local magnitude (ML) scale, assigns a single number to quantify the amount of seismic energy released by an earthquake. It is a base-10 logarithmic scale obtained by calculating the logarithm of the combined horizontal amplitude (shaking amplitude) of the largest displacement from zero on a particular type of seismometer (Wood–Anderson torsion). So, for example, an earthquake that measures 5.0 on the Richter scale has a shaking amplitude 10 times larger than one that measures 4.0.


  363. Troy Martel,

    Excellent post on perceived risk! I have noticed the same fears. I suspect many associate nuclear power plants with atomic bombs and fear “meltdown” will be like an atomic explosion. Yes, anyone with any science education knows better.

    But only about 20-25% of Americans are scientifically literate. Even some of those distrust science because of the creationism vs. evolution debate.

    Most of the media reporters are scientifically illiterate too and even their “experts’ they use to explain things. I saw Bill Nye- the science guy on CNN explaining that the cesium being seen in the accident was due to melting of the cesium control rods in the reactor that used cesium to absorb neutrons, and this was evidence of a core melt down. WHAT!!!! Cesium is a fission product and isn’t used in control rods. Google “Nuclear control rod” to see the real materials used.

    But the media have a problem. A real expert uses words that few of the audience understand, What is cesium? What is a control rod? What is a “fission produce”. So the lack of trust is based on lack of true communication.

    However as IJudge Judy said, ” I can’t fix dumb!”

    So I share your that fear politics will win out, A majority of voters will vote “NO” for nuclear, and also “NO” on “coal”, and “NO” on “solar and wind”. Then when the rolling blackouts begin here in the USA they will scream “Why didn’t “THEY” do something to prevent this!”


  364. Dave Kimble, on 15 March 2011 at 12:20 PM — Seismologists no longer use the Richter scale; the author of the embedded report was wrong in misinterpreting ‘magnitude’, abbreviating moment magnitude, as ‘Richter’.

    The initial assessment of the earthquake was magnitude 8.9; USGS has now revised this to magnitude 9.0.

    I don’t know where the design basis of 8.2 came from in the embedded report, but it is rather silly to compare two such magntudes except at the epicenters. The accelerations to be withstood are what the engineers design for.


  365. PacificNW Don, on 15 March 2011 at 12:29 PM said:

    I suspect many associate nuclear power plants with atomic bombs and fear “meltdown” will be like an atomic explosion

    For credibility’s sake – please provide evidence.

    You forgot to mention that the majority of voters will not vote “NO” for baseload renewables, and therefore will not have to scream in the USA or anywhere else for that matter.

    Only capitalists scream.


  366. Part of my trainng over the years included the reason for the 2200 degree limit on zirconium. It is the critical temperature at which the H2O – Ziconium reaction becomes self sustaining and exothermic. Basically the zirconium burns in water like potassium. The result is zirconium oxide and hydrogen gas. The oxidizing of the fuel rods is what creates the largest hydrogen hazard in this type of accident. This also results in the release of the fission product gasses such as iodine.

    The media use of so-called “experts” who have advanced degrees but are obviously ant-nuclear is so blatent that I choose to ignore them.

    One must also be careful of comparing this accident to Chernoble. Anyone who has read the NUREG on Chernoble will recognize that the “explosion” there was the result of re-introducing water into the boiler portion of a graphite moderated reactor while it was still critical. It had a steam explosion. Chernoble had a very high positive void coefficient, so the reactor power level actually increased when feed water levels dropped too low.


  367. David B Benson
    I know that seismologists don’t use the Richter scale any longer.

    I was pointing out what you have now agreed – “the author of the embedded report was wrong”.

    Would you also care to agree that the half-life of Caesium-137 is 10.76 years and not “a few seconds” ?

    The trouble is, so many of the readers here have gone away with the impression that the author is right, and everyone else is wrong, probably because that is what they wanted to believe in the first place.

    This hasn’t been helped by your attack on me, which it now seems you are withdrawing without apology. It all adds to the confusion, which protects interests that just can’t face the facts.

    The Telegraph now reports:
    “A huge explosion hit another reactor at an earthquake-damaged Japanese nuclear power plant early Tuesday, the third blast since Saturday, the plant operator said.
    “There was a huge explosion” between 6:00 am (2100 GMT Monday) and 6:15 am at the number-two reactor of Fukushima No.1 nuclear power plant, a Tokyo Electric Power Co (TEPCO) spokesman said.

    The government also reported apparent damage to part of the container shielding the same reactor at Fukushima 250 kilometres (155 miles) northeast of Tokyo, although it was unclear whether this resulted from the blast.

    Chief Cabinet Secretary Yukio Edano told reporters the suppression pool of the number-two nuclear reactor appeared to have been damaged. ”

    – so it is far from over.


  368. to Chris Warren,

    ‘I suspect many associate nuclear power plants with atomic bombs and fear “meltdown” will be like an atomic explosion”

    “For credibility’s sake – please provide evidence.”

    First an apology- I am not familiar with how this site uses quotes and there is no preview function so I hope this displays OK in readable form.

    Glad to show some examples of how it is necessary to point out to readers/viewers that these explosions are not nuclear. :

    A number of articles take the pains to point out that the explosions are NOT nuclear explosions;

    For Example:
    Discover Magazine


    “Here’s what happened: The plant has six reactors. The earthquake and subsequent tsunami severely damaged some of the reactors and hampered attempts to fix them. An explosion rocked the plant on Saturday, and another about a day later. These were not nuclear explosions! ”

    Bellingham Herald:


    Q: Exactly what is a meltdown, and why is it potentially dangerous?

    A: A meltdown occurs when a reactor’s radioactive core, which holds its uranium fuel, gets so hot that it begins to melt. A complete meltdown can breach a reactor’s steel pressure vessel and other protective barriers – and spread radioactive byproducts like iodine and cesium into the surroundings. That endangers the environment and nearby residents. However, a reactor will not explode like an atomic bomb.

    The Way entertainment shows portray nuclear accidents:


    Many have seen this type of portrayal of nuclear :

    “Both nuclear weapons and peaceful nuclear technology are enormously technical in nature. Since Hollywood never lets boring facts get in the way of an engaging yarn, this allows some truly mind-bending violations of physics to make it by most audiences. They can basically be summed up like so:
    Related to Shur Fine Guns and Stuff Blowing Up, if something is nuclear, and something, anything happens to it, it’s Going Critical and gonna blow up like an atomic bomb. It doesn’t matter if it’s designed not to do that, it doesn’t matter if it’s not radioactive enough to be used for an atomic bomb, it doesn’t matter if it hasn’t got enough material for critical mass, it’s gonna blow.”


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  372. Dave Kimble, on 15 March 2011 at 1:05 PM — You went about the seismology bit completely incorrectly. As it turns out, I already had posted a proper correction for that as a comment yesterday.

    So that everyone is clear on the matter, that part of the embedded report can only be characterised as, at best, muddled and your (and others) attempt to correct it just made matters worse.

    has a half-life of about 30.17 years, so I won’t agree with you about that, either.


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  374. Can someone please provide some follow-up comments on what is happening with reactor #2? The pressure vessel seems to have damaged and radiation leakage has been confirmed by the Prime Minister in a nationally televised address.


  375. Pingback: Daily SG: 15 Mar 2011 « The Singapore Daily

  376. This was a great article. Could the same author explain the explosion from reactor number three which occurred Monday morning and reportedly contains the highly potent MOX Fuel with a half life of over 20000 years. I would like to know how our (US) govt is going to monitor the radiation over th Pacific Ocean and its impacts upon us and the marine life.


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  378. Sorry, one more time

    “There was and will *not* be any significant release of radioactivity.”

    This has turned out to be a fallacy. There HAS been a significant release of radiation. No. 4 reactor had an explosion, the containment has most likely been breached, and radiation levels have gone up thousands of percents.



  379. I just wanted to post and say … God there are some really smart people here. This stuff is wayyyyyyyy over my head but its simple enough to read. Amazing stuff, really is.

    To all you ‘nerds’ :-) Keep up the good work. You make me want to work harder.


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  382. Great article Barry. You did not mention which model of BWR is at Fukushima but its an earlier model like BWR 2 or ? Its a tribute to GE’s engineering that this BWR and containment held up pretty well. Of course the latter days BWR’s are probably a lot safer.


  383. Why did they turn off the electrical genrator when the reactor shut down? If it was not damaged, they could have continued running the turbine and generating electrcity (even if they had to send it through a dummy load). That’s a good way to carry off the excess decay energy.


  384. Ms Perps,

    In the grey table in the blog post you link to

    ExternE is quoted as listing not only 0.04 deaths per TWh for “occupational fatalities”, but also 0.65 deaths per TWh for “public fatalities”. Why does your source, and then you, only quote the first number in their little table?

    BTW the same grey table refers to an ExternE publication from 1995, whereas your linked ExternE report

    Click to access 15%20-%20Polenp~1.pdf

    is from 2001 — and, as far as I could find, contains neither number. Sure you’re not mixing up two reports?


  385. The plant operators have been evacuated from their locations due to risk of radiation and explosions. I would like to know: How can containment be effectively controlled if the lights aren’t on and nobodys home????? Don’t the nuclear operators have to manage this from their control room or can it be done at another offsite location remotely????


  386. The author does a good job but makes some incorrect statements.

    I offer the following rebuttal based on my nuclear background (several years of operating, testing, maintenance on U.S. Naval reactors, I have studied the Chernobyl and Three Mile Island accident reports and I have written disaster drills that were used to train civilian personnel in the event of a reactor accident on a U.S. nuclear ship while in port under repair – etc.).

    Chernobyl was a “prompt criticality” accident which IS a nuclear type explosion (but not with the efficiency of a nuclear bomb which is designed to explode). The Chernobyl accident was not due to pressure buildup as the author claims.

    Also, as soon as the zirconium metal melts in the presence of water, it produces hydrogen gas. The hydrogen explosions at the Japanese power plants were due to hydrogen given off by the melting zirconium. This is proof positive that very significant melting has occurred. Three Mile Island also had several hydrogen explosions due to the melting of the core but they were all contained within the containment dome since the TMI design does not have a building outside of the dome.

    The author is also in error about Iodine and Cesium being the only fission products of concern and that they are now essentially gone. Cesium 137 has a 30 year half life. Iodine 131 has a half life of 8 days. Radioactive Isotopes are not considered “gone” until they have experienced five half lives (150 years and 40 days respectively) There are hundreds of fission products and associated isotopes that result from the fission process of Uranium. Some are gasses, some are solids, but all are VERY radioactive for various lengths of time based on their half life. If the reinforced containment is breached, these fission products will be released to the environment with very significant and long term adverse consequences.

    The boric acid is a liquid neutron absorber. It is being added so that if the uranium pellets (which are no longer being held in place by the zirconium -which has melted away) fall to the bottom of the pressure vessel, that the resulting new geometry of uranium fuel does not become a “critical mass” which would again restart the heat of nuclear fission, or worse, create a prompt criticality like Chernobyl. The Russians also had to worry about the remnants of the exploded reactor going “critical” again which is why they had helicopter pilots drop boron into the exploded reactor vessel. These pilots subsequently died soon after from radiation exposure.

    This meltdown is much more serious than the author portrayed. However, he is correct in stating that if the containment is not breached, then the disaster will be limited, just like it was at Three Mile Island. However, if the containment is breached, the tens of thousands of Rem (measure of radiation) per hour of fission product radioactivity that will be around for decades will be spread into the environment and create a disaster similar to Chernobyl.

    If a person receives 500 Rem in a short period of time, they have a 50% chance of dying. Typical background radiation is about 100 millirem (one tenth of a Rem) in one year.

    It is foolish to build nuclear power plants in areas that are likely to experience tsunamis unless they are engineered to deal with them.

    Hope this helps.

    Kevin Lea


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  393. @ PacificNW Don

    Excume me? Did you just mention “rolling blackouts” in the US?

    Not ever relevant my friend.

    This from someone who lives 215 miles from the plant in question; on the island called Japan that was hit by a very large earquake on Friday; which endured many tsunami(s) following; which IS experiencing REAL rolling black outs. When I read your comment it made made sick because of its inherant selfishness.


  394. To have one reactor melt down because of an unfortunate sequence of events, and the diesel plugs not fitting, sounds like an accident. Kevin Lea, I am very concerned by your insistence that melting zirconium somehow gives off hydrogen, is this a new form of elemental transmutation you have discovered ? Of course the hydrogen comes from the dissociation of water at extreme temperatures over 2000 in the presence of a reducing agent – how else are you proposing this hydrogen is formed ?


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  397. “That article is heavily biased. F.ex. the person interviewed works for windpower company and they are competing with nuclear…”

    F.ex. a “conflict of interest” is not a “bias”. In particular if it comes to a subject so mathematical as nuclear physics. How about some actual facts supporting your vague allegations? [deleted ad hominem attack]


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  401. Guys, I think you should take this article off the site.
    It might be scientifically accurate but considering the latest developments clearly wrong, starting with:
    “There was and will *not* be any significant release of radioactivity.”

    I think it’s worthwhile to retain this and the other related articles and associated comment threads. There’s a lot of material here we need to go through in time to come.


  402. What was written here made far too many assumptions about how events would proceed. Engineers like to imagine that they can control for all possible variables. Unfortunately in this case the level of devastation took the management of these reactors into the complex domain where non-linear behaviour was much more probable.

    It is worth keeping all this published information so that lessons can be learned about prematurely reaching conclusions without the full picture.


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  406. This article offers lots of good insights, but also buffs over some other important points. I am sure it was not intentional.

    Just on the facts: “RBMK reactors they used both graphite and light water as moderator…”

    It should be noted that the RMBK 1000 reactor at Chernobyl did not use water as a “moderator”. The moderator is the substance (could be a lot of things from graphite, to gas, to light water to heavy water) that helps trigger the chain reaction by slowing down released neutrons so that they are slow enough to agitate the U-235, as explained by Soylent above. The water in the RMBK reactor is actually an absorbent in comparison to graphite. You are right that graphite is a more efficient moderator than water, but what is important here is the relative value of neutron absorbency of the water and the graphite in relation to your reactor design, the materials you use and the point you chose to achieve “criticality”.

    In the RMBK, as the graphite moderator rods are inserted into the core to increase reactivity, they displace the water that is actually helping to dampen the reaction.

    Because the operators were conducting a low water pressure test “voids” (bubbles in the water) that normally would have been pushed out under pressure remained, allowing for more reactivity and greater heat, which in turn vaporized more water in the system. Steam has practically no absorbent quality at all. This is why the reactivity of the core increased when the water in core began to vaporize and this caused the positive feedback loop and the power surge, and the FIRST explosion.

    There were two explosions at the Chernobyl plant within a matter of minutes, not one. It is generally agreed that the first was a simple pressure explosions caused by vaporizing water, the cause of the second, which was caused by the first, is disputed. A common theory is that the second explosion was caused by Zirconium releasing hydrogen and then igniting as you describe, but other prevalent theories suggest that there may have been a “nuclear excursion”.

    You are correct that the biggest problem with creating a bomb is keeping the fissile material together long enough to actually create an atomic explosion, because once the material comes together it is ripped apart through the kinetic energy of the reaction, unless it is contained. However, if enough material comes together even for a short period of time it will create a burst of heat and energy as the fissile material expands, and this could have been what ripped open the containment at Chernobyl.

    The truth is, no one really knows what happened in that second explosion at Chernobyl, just as no one really knows what is going on in the reactor vessel at Fukushima, the fact that the circumstances that led to this condition is pretty much irrelevant. It is clear that the situation is barely in control, if at all.

    We can make some guesses however about what is going on and the fact that there are hydrogen explosions happening caused by Zirconium being heated enough to expel hydrogen gas in quantity, suggests that it is getting pretty hot in there.


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  408. More importantly, however, I think we have to salute those brave people who are staying on site in an attempt to prevent catastrophe from happening. People are taking serious risks to bring this under control and those people are really the best among us.

    More that 20 have been injured. There may indeed be deaths, both from radiation exposure, and other causes.


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  411. Well written post. Please explain why if there is no cause for alarm the following is happening:

    1. Radiation levels at the quake-stricken Fukushima Daiichi complex have varied wildly, with a reading of 11,930 microsieverts at the main gate of the plant at 0000 GMT, up from 596 microsieverts as of 0630 GMT.
    2. Elsewhere at the plant, levels reached as high as 400,000 microsieverts an hour (or 400 millisieverts an hour).
    3. Radioactivity at the cooling pool is high and Tokyo Electric cannot make checks at the site or determine what has burned.
    4. Radiation leakage from complex is likely to spread after a fresh explosion at the plant.


  412. Give the guy a break; he was writing this as an email to family in Japan. I don’t think he intended it to be spread all over the internet (his cousin posted it on a blog), so it doesn’t have some technical details right, and ends up with many completely wrong conclusions.

    But that’s OK; he was simply trying to comfort his family–not trying to write a journalistic article or scientific analysis!


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  415. Nuclear energy is a very sensitive subject, even if for civil uses. As humans we are unable to sense radioactivity levels whether they are at low levels or letal ones. For that, we need instruments like geiger counters for ex.
    Hence it is easy for governments and corporations to hide relevant information about radioactivity levels, and human health threats as had been shown in the past.
    This article is quite detailed about nuclear reactor technology, but the conclusions seems premature.
    I fear this catastrophe could be much greater than Tchernobyl, but I could be wrong.
    So lets wait and see (and don’t trust official sources -never-). Better sources are independant labs like this one http://www.criirad.org/


  416. Thank you for righting this article, the best piece I’ve read a long while. The paranoia around the issue is just frustrating, time for humans to kill the earth while avoiding ‘nuclear power’.


  417. people near the reactors might not have the luxury of waiting to see what happens, that is my point…there may or may not eventually be a disaster (I don’t think anybody really knows at the moment) but I’m pretty sure that it is abundantly clear there is at least a very high risk and that people should take immediate precautions (i.e. I would get the hell out of there ASAP if at all possible) but everyone is stil telling them it will be all ok and not to worry.


  418. Interesting, but it still leaves a lot of questions as to why radiation levels are suddenly extremely high today, and have even elevated as far away as Tokyo.

    My hope is that you are right, but my gut tells me this is far from over, and even farther away from “safe”.


  419. latest release is 400 millisieverts per hour. Not sure the reaction has quite stopped yet. But keep singing zippidy doo dah Barry.

    Old news. That spike died down some time ago. It was most likely coming from uncovered spent fuel. Presumably that situation is rectified.


  420. Pingback: The Truth on the Reactors in Japan | Eric Lee dot net

  421. There is clearly a lack of information about what really happened. Because the accident is much more serious as what is claimed in this article (we had to wait for a strong public claim by French Authority of Nuclear Safety, that this was a Level 6 accident and not a Level 4 as wrongly stated) to see the Japanese authorities starting to call for international help and admit that reactor 2 (whose external shelter did not explode) has adready melted and that the inner shell was already damaged.

    But now things are clear for nuclear plants: the main danger is not the earthquake but damages to external cooling systems : in France we had last year the Katrina storm that flooded the areas around a nuclear plant in Gironde, causing failures to the sources of cooling waters. Now there’s a wall around the plant supposed to keep the area out of polluted waters, and maintain the generators, pumps, and water cleaner bassins safe.

    But now we clearly need something else : we need to build those generators on higher stores, and also build reserve bassins for purified water, enough to support a massive evaporation in case of temporary failure of the electric grid.

    We also need to develop a way to use the produced hydrogen as a regular fuel to generate the energy for the pumps, instead of making it blast within the first outer containment, and risking to damage other outdoor structures (surrounding reactors, geenrators, pumps, bassins).

    Clearly, those reactors are missing a security reserve of cooling water in case of emergency.


  422. You say:-
    By “significant” I mean a level of radiation of more than what you would receive on – say – a long distance flight, or drinking a glass of beer that comes from certain areas with high levels of natural background radiation.
    If the danger is so low, why then does the nation order those living within 20 kilometers to evacuate the area?
    Also this plant had a fatal design flaw that was overlooked. Its location was vulnerable.


  423. JAIF report at 19:00 in Japan:

    Click to access ENGNEWS01_1300189582P.pdf

    shows temperatures rising in #5 and #6 spent fuel pits, while they are injecting water into sfp of #4.

    So it would seem that they haven’t been injecting salt water into #5 and #6 all this time, presumably so as not to contaminate the spent fuel rods, and relying on the amount of water in the pit to keep them cool.

    The water level in #4 fell so low that the rods were exposed and generated Hydrogen, which caused the fire. Presumably there is the possibility that the same thing will happen to #5 and #6, and the entire 4.4 GW complex could be wrecked.


  424. Also, there’s a compeltely false claim in the article: the cooling rods are NOT completely stopping the nuclear fissions. They are just stabilizing them. But as in normal operations the fuel rods and cooling rods are both solid, they do not stop reacting in themselves. Another system must also be installed to allow removing the uranium bars out of the central chamber back to the coling bassins from which they are inserted, separating them much more than what the cooling graphite rods are doing. If a plant must stop operating and has no more external power source, to maintain the normal cooling, this extraction of the fuel bars should start immediately, even if this makes the fuel unusable for later reoperation.

    I really cannot understand why TEPCO did not start the complete stop immediately given the limited timeframe they had to restore the normal cooling and given the huge difficulties or impossibility to restore the power grid in an area that was so massively damaged by the tsunami.

    A lesson to learn : we had certainly prepared all plants only to resist to massive earthquakes, without taking into account the damages that would have occured in regions around the plants. And there, floodings (not just tsunamis) are a major risk in almost all places where plants are built (because they are alsmost always near a massive source of natural water (large river or sea).

    Now it’s time to upgrade and protect the water sources to support the needs for several weeks (and not just a few hours or days like in Fukushima), and to install oil reserves for turbines and pumps, and to protect those reserves and external systems.

    The Fukushima catastrophe has also demonstrated that a simple blast of a modest quantity of hydrogen can damage the protection shells. This is clearly opposed to all the past claims that the plant would resist to a terrorist attack such as a bomb, and notably when the plant is not already running in normal operation but is stopped.

    [Deleted ‘lies’ accusation: one more strike and you’re out]


  425. Pingback: USA: Science Bloggers Explain Fukushima · Global Voices

  426. Philippe, please moderate your language re: “lies”. You have been put on moderation. (I honestly don’t know why I’m being even slightly tolerant of this anymore, too little time and too much nonsense/vitriol to moderate).

    Reminder to all: ALL COMMENTS THAT BREAK BNC COMMENTING RULES WILL BE (ARE BEING) DELETED. You are welcome to disagree, but do so respectfully, factually, and with more substance that a random shot out of the window.


  427. Watching our local media go into meltdown has been a wonderful lesson in how not to report events such these. No one seems to even mention the fact that other nuclear reactors in the region performed well (and have been safely shutdown after a colossal earthquake) before they launch into comparisons with Chernobyl. So ‘balance’ is out and hyped hysteria is in…the first rule of ‘journalism’, apparently. One online journal even put a graph of someone’s geiger counter readings from Tokyo for the last two days! And said the thing needed no translation! (I kid you not).

    But seriously, there are engineers at that plant coping with the effects of a catastrophic force of nature under unimaginably difficult conditions, doing their best to avert the worst outcome, risking their own lives, and it seems a little bit opportunistic to be jumping to the conclusion that this event is the death of nuclear power. More like the death of reason, and by the look of a few posts here, the death of civility.


  428. Interesting: in Germany the close down the AKW Neckarwestheim I forever. They seem to react pretty quick on the situation over there.

    Are there any news like that from any other country?
    I am just interested.


  429. @TR
    “Excume me? Did you just mention “rolling blackouts” in the US?
    Not ever relevant my friend.”

    My apologies since the post was intended to comment on how the public fear caused by these tragic accidents in Japan are affecting politics in the USA about nuclear power safety and referred only to future US rolling blackouts like Japan has now, if we in the USA don’t do something about our aging electric grid that is maxed out and fragile.

    A magnitude 9earthquake and tsunami HAS occurred on the US west coast ( Northern California, Oregon & Washington states) about 1700 AD and reoccurs every 300-400 years. The “Big one’ in LA is also overdue.

    WE in the USA are now due for the same sudden jolt to our electric systems and West Coast populations as Japan just experienced. Will we prepare?

    I was referring the the growing view that this tragic series of horrible events in Japan will change public perceptions of the safety of nuclear power and slow the future expansion of new nuclear power plants here in the USA. There are over 20 BWR nuclear plants in the USAA using similar designs as these in Japans. Even now some in Congress are calling for a halt to renewed nuclear expansion

    The USA needs to move about half of its transportation from by oil to fueled by electricity. That means electric cars, light trucks and an electric train system like Japan has sets the world standard for electric trains.

    The CEO of FedEX expresses this well in this article:


    Since the US must reduce use of coal fired plants while doubling the electrical capacity in the next 20 years, nuclear power has to be used if we are to also meet CO2 climate concerns.

    Thus IF this Japanese nuclear accident prevents nuclear power expansion in the USA, and coal plants are also curtailed, i was predicting the USA will experience reduced e electricity available , not doubling of electrical power needed.

    The result will be rolling blackouts in the future here in the USA..

    Don’t get me wrong. I spent the last 15 years of my career working on geothermal electrical energy and support solar and wind energy too. But do the math. None to these energy sources can scale up in the next 20 years to double the total USA electric supply.

    The new reactor designs now being built have such features as thermal convection cooling if backup generator power is lost in an accident and are much safer than the 40 year old designs in both Japan and the USA.

    I think the lesson from this tragedy In Japan is to learn how to make emergency backup power and water cooling more robust. It is a wakeup call to replace these old reactor designs with new ones, rather than give up on nuclear power, Just look at the deaths in the oil and coal industries and their environmental damage and ask if we want to double those industries instead of nuclear power.

    Energy must come from somewhere. Where?


  430. Concerning Neckarwestheim:
    There are elections there pretty soon. But additionally Germany has had a very strong anti-nuclear movement vor about 20-30 years now.
    Chancellor Merkel (strongly pro-nuclear) is right now ridiculously turning her coat.
    Sentences like “In this light nobody in their right mind could say our plants are secure. They are secure. …” are often these days. Its all quite silly…


  431. This is a very great paper by an expert in the field. However, it requires critical review. I have noted in this paper that the dangerous element released in the atmosphere is Caesium amongst others. The author plays down the danger of Caesium and the other elements by arguing that they were released in small amounts and have a half life of few seconds. While this is true even for certain isotopes of Caesium, it is absolutely not true for Caesium in general. Caesium has a total of 39 known isotopes. The radioactive 135Cs has a very long half-life of about 2.3 million years, while 137Cs and 134Cs have half-lives of 30 and 2 years, respectively. Unless the released Caesium was one of the metastable nuclear isomers, the danger does exist in my opinion. My question is, “What isotope of Caesium was measured/detected?” I find this to be the important information missing in this paper.

    My question is based on the statements that caught my attention in his paper as below.

    #Subtitle: Fundamentals of nuclear reactions
    1. “There is a multitude of fission products that are produced in a reactor, including cesium and iodine.”
    2. “…these fission products decay extremely quickly, and become harmless by the time you spell “R-A-D-I-O-N-U-C-L-I-D-E.” Others decay more slowly, like some cesium, iodine, strontium, and argon.”

    #Subtitle: What happened at Fukushima (as of March 12, 2011)

    3.”While some of these gases are radioactive, they did not pose a significant risk to public safety to even the workers on site.”

    4. “At this time, some of the radioactive fission products (cesium, iodine, etc.) started to mix with the water and steam. It was reported that a small amount of cesium and iodine was measured in the steam that was released into the atmosphere.”


  432. Please note that the cladding does not need to reach or exceed 1200 C to produce hydrogen sufficient to cause the hydrogen explosion. Hydrogen release is a function of both time and temperature. The cladding could have been at 800 C for several hours to produce hydrogen in large enough quantities. This is important to note because lower temperature would result in less damage to the core and more possibility to continue cooling the fuel.


  433. The news just reports that they want to cool down the reactors with water spilled out from helicopters. Maybe I am wrong and have a lack of insight, but that sounds not like routine procedure to me – rather a bit helpless.
    They do that because they say the risk to get contaminated on the ground level is too high.

    Anybody heard of something like that before?
    It is good they try everything possible though….


  434. Questions:

    1) When do they drop the cement on all the reactors to entomb them? I assume that is the last line of “defense in depth”.

    2) Will the chopper pilots who drop the cement also die like the ones who did that at Tchernobyl?

    3) When will the 50 workers die who remained after the containment broke in reactor 2 today? Those of you who are saying “risking their lives” are not grasping what these 50 people are really probably doing. It sounds like suicide in the name of saving their country, which is what heroes did in the Ukraine in 1986.

    I don’t see the CEO of Hitachi or GE heading to the plant to be one of those 50. I also don’t see nuclear power salespeople heading that way to help nor buy Tokyo real estate.


  435. Although this article was initially distributed to bring about clarity and reason, the blogs which have ensued have reflected the hysteria which is transpiring everywhere. What shocks me is the ignorance among experts in this field – on BBC last week, one British scientist was asserting that reactor number one had already burned through its steel containment vessel and was “shining out” radiation at the world (seemingly ignorant of the fact that all that water would, in such a case, have caused a massive and visible chemical reaction) – at the other extreme we have the opinion of poor Dr. Oehmen, above, which now appears to be just a little optimistic.

    Now, let me ask, as a non-specialist, if the rods all melt and form a nasty molten glob at the bottom of the reactor, is there going to be some FISSION within that glob or is all the heat then generated the result of radioactive decay?


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  437. Very enlightening post. One thing I can’t seem to grasp, (and it may have been addressed in the follow-up posts – my apologies if so): If there is still steam from the reactor, and the reactor is designed to generate electricity with steam by design, why can’t that steam now be used to generate the power necessary for cooling? My only guess is that the turbines may have been damaged by the tsunami, but seems to me that such a critical component as the backup generators should be protected almost as strongly as the other controls for the reactor – maybe even within the secondary containment area.

    Is such a design possible?


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  440. I have a question for Barry.
    I read in the swedish newspaper, Aftonbladet, that one of the reactors are driven by, not only uranium, but plutonium as well.
    Would this be a definate riskfactor or does it work in same fashion as a normal BWR?
    In a sense, can the plutonium and uranium collide and cause worse damage than the other reactors in a worst case scenario?
    Sorry if my enlish is a bit rusty. 10 years since I studied it! =)


  441. @enno, on 15 March 2011 at 5:01 PM said:

    Quote: “…I am very concerned by your insistence that melting zirconium somehow gives off hydrogen, is this a new form of elemental transmutation you have discovered ? Of course the hydrogen comes from the dissociation of water at extreme temperatures over 2000 in the presence of a reducing agent – how else are you proposing this hydrogen is formed ?”

    To answer your last question search the above posts where several posts, including a post of mine, discuss the highly reactive properties of the zirconium alloy fuel cladding which rapidly reacts with steam when the fuel is uncovered and fuel temperatures rise. The chemical reaction and source of hydrogen is:

    Zr + 2 H20 = ZrO2 + 2H2

    The conversion of the metallic zirconium fuel cladding to ZrO2 changes the strong metal into fractured oxide with the color and mechanical strength of egg shells, Hydrogen is also absorbed into remaining metal causing embrittlement and fracturing. The cladding first cracks releasing fission products. It this continues the fuel rod cladding can break away exposing the ceramic uranium fuel pellets and even letting them drop out into the bottom of the pressure vessel in the worst case scenario.

    I have personally run high temperature water and steam laboratory experiments in high pressure autoclaves observing and measuring this process back in the 1960s

    This is not “melting”. It is an uncontrolled oxidation by excessively hot fuel cladding in steam and occurs at overheated conditions well below the melting point of zirconium. This oxidation can be so fast in super hot steam that I question that any zirconium would be left to melt.

    The large quantities of hydrogen released imply extensive core damage has occurred in reactors 1, 2, & 3.

    Hope this helps the understanding.


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  446. Thank you for posting this article. It sounds like this reactor design was built for safety and thanks for taking the air out of these published reports that speak doom and gloom when in fact the Japanese sound like they have a firm handle on this situation. It was an impossible scenario for this plant yet quick thinking and well trained engineers have played by the book to keep things from going out of control. They aren’t getting enough credit.

    I support nuclear power until scientist can develop a better alternative for future generations. Our world just keeps growing and consuming more power.


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  449. Good post.

    @Coalburner I agree with your assessment, but my point is that amid all the panic (and arguments and debate) there is very little appreciation of the selfless acts of these people, similar indeed to those who volunteered to help contain the reactor, and the thousands who came to clean up the exclusion zone afterward.

    These are truly heroic efforts, being done by some very brave people. And in fact, they aren’t just doing it to save their country, but are doing it for the sake of us all.

    People around the world need to appreciate and recognize that fact.


  450. Am I wrong or is that the ocean over to the left on the Aeril photos~\!
    Yes the temp generators would not mate with existing
    However those generators can power 8 to 10 in pumps with a temporary pipeline that locks together and can be laid above ground and water can flow in I know in 10 hrs because I have done it!
    No need for helo’s that pipeline could be flooding water in that reactor in one day!
    What is the matter with these people do they not have any common sense!!!!!!!


  451. The bottom line is that people have an irrational fear of radiation. Maybe some of us with a psychological/literary bent can figure this out, but it is a truly nutty characteristic of late 20th century/early 21st century humankind.

    Take a look at Germany. So they are closing all of their nuke plants to look at the “human risk?” What about looking at rates of cigarette smoking in Germany, and trying to reduce that–you’d save far more lives over the next 40-50 years than turning off 20% of your power production at who knows what cost.

    Barry, I didn’t know who you were before this site got some play. I don’t necessarily believe the data are all that tidy and complete on global warming. However, I believe like you do that nuclear energy, especially with the modern designs, is the way to go–this is and should be a compromise on which warmists and non-warmists agree.

    This site, and a few others like it, are a true antidote to our current popular press. Look at the Drudge Report (where likely all of our current press goes first before trying to report) –pure hysteria. As you noted before–this is a country which likely has upwards of 20,000-50,000 people dead right now from this catastrophe–that is the true story here, and the one that we should remain focused on.

    Again, thanks to you and to all of the discussants — many of who appear to be very well versed in nuclear engineering — for allowing us interested laypeople to understand potentially what is going on in Japan right now.


  452. I thought the tsunami damaged the circulating cooling system, not just the generators. An engineer who designed the pressure vessel had an English press conference yesterday said that.


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  454. Flood the reactor site with sea water from the ocean with the pumps and pipeline to cool the cores! when tangible,
    Start with the concrete and when cooled encase those suckers in concrete 5 times the size of the buildings!
    Walk away and monitor the site forever !


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  456. I find it somewhat astounding that there was a fire in the spent fuel rod pond. In all my readings of loss of coolant accidents the possibility of the spent fuel releasing radioactivity has never been mentioned. I would have thought it would take a long time to evaporate the water in these ponds even if no water is being circulated to cool the rods. Was this hydrogen again, electrical wireing or the rods themselves? This is where most of the long term radioactivity is stored. Much more than in the reactors themselves. There is no more than minimal containment for the SFP.


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  458. Pingback: Fukushima Nuclear Accident – a simple and accurate explanation (via BraveNewClimate) | observadordomundo

  459. @cancerdog:

    the fear of radiation is everything else but irrational. we cannot see, hear or smell them, but we know in the right (or wrong) dose the are poisonous for our body. radiation is for us human beings like a ghost, but a REAL one, so i would not call the fear of it ‘irrational’.

    a truly nutty characteristic of the 20th cantury? you think so? i think so too! and why is that? because BEFORE people simply didn’t know about x-rays for example:

    (from wikipedia:)
    Röntgen’s original paper, “On A New Kind Of Rays” (Über eine neue Art von Strahlen), was published 50 days later on 28 December 1895.

    the comparison about smoking and nuclear power is a bit funny, too. and besides that: there is hardly a place in Germany where smoking is still allowed. i don’t know what you want to show with this comparison anyway….?

    and actually i cannot see the press focusing on the coverage of JUST the nuclear catastrophe which is coming up. where i am this is pretty much equal. there just as much to hear about the tsunami (if there was one) or the earthquakes (when they occured) as about everything else.


  460. sophia – I tihnk the experts are quiet because not much is happening. Plus it’s early yet in Australia where this blog is based.

    JD – As a fallback, the same strategy that worked for the fuel melt at Three-Mile Island will work here. Leave the reactors to cool down – maybe five years, maybe ten – then dismantle, extract the fuel, decommission the buildings.

    But there may be better options now. Once the reactor vessel is flooded and circulating, it will probably be possible to take the reactor lid off (or make an access port) and start investigating the damage with remote cameras, and planning the next steps.

    And no, the radioactivity is not at an intolerable level forever. Not even close. Indeed, why would power stations ever need refuelling if that were so?


  461. The rods have been exposed you are talking a different deal!
    Radioactive particles are already intense!
    You Don’t Tug on Superman’s Cape and you don’t Open a containment cell that has rods exposed!!!!!!!


  462. The Major problem to begin with was water to cool the site!
    All common sense went out the window because It’s Nuclear!
    Well it may be Nuclear but all you needed was water to cool the system!
    Now yes you have a major problem!!!!!!


  463. a spokesman of the japanese nuclear department just said, that they are missing two of their workers and that the roof of reactor 4 broke. because of the explosion yesterday radioactivity could escape, which lead to a ten times higher amount in Tokyo than usual. and around the power plant the amount of radioactivity is carcinogenic. :-(


  464. Great c/m in place until this type of catastrophic event ( Tsunami) happened. The question is how come we over look the simple aspect that a country that gets hundreds of earthquakes with intensity range between from 1-9 would still consider nuke plant/energy? Japan should get nuke energy but not necessarilry produce it on its soil. IAE should review pre requisites for a nuke plant. Developing nations face the heat when coming to asking for uranium, what is happening here?


  465. yes, you seem to take the technical portion pretty serious. i am not chastising your grammar. i just told you that the punctuation distracts from what you write. as you seem to comment on the technical portion how you write becomes a part of that, because people have to read it if they want to follow.


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  467. Ok I’ve said my peace and It’s logged!
    To late now any way!
    Sopia I hope you go on to be a great Grammar teacher!
    This site is yours now take care of it and make sure everyone adheres to your rules of engagement touche’


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  471. i find it hilarious how much controversy, and then controversy on top of controversy, and then skepticism on top of controversy this single event is creating. Everyone’s right, yet everyone’s wrong. Controversy cleared


  472. Thank you for the article. I can’t help but notice that its present tone is a lot more humble than the March 13 version dismissing the concerns of uninformed laypeople.

    That overconfidence is something experts always have to watch out for.


  473. William Fairholm, on 16 March 2011 at 7:19 AM said:
    “I find it somewhat astounding that there was a fire in the spent fuel rod pond. ”

    It seems the spent fuel rods sit in a deep pit full of water, covered by many metres of water. If the rods are recently removed, they will still be very hot for a long while, and it would take days for the water to boil away to the point that the rods were uncovered. Nevertheless this seems to be what has happened in the #4 pit, releasing Hydrogen, which caused the fire.

    The JAIF report for 19:00 15 March:

    Click to access ENGNEWS01_1300189582P.pdf

    shows they are filling the #4 pit with water (presumably seawater). It also reports the temperature in the #5 and #6 pits is increasing, which implies the water level is going down.

    These reports now seem to have been stopped:
    which only compounds the uncertainty and confusion. If anyone has an alternative quotable source, do post the link here.


  474. Hello everybody.

    I stumbled across this site whilst doing some internet research (i.e. trying to educate myself!) on the unfolding events at the stricken nuclear plant in Japan. The explanation in the original post and the following replies have been a fascinating read and it’s obvious that there are some very knowledgeable posters, some of whom have had first hand experience in the the nuclear industry.
    With that in mind I would be extremely grateful if some of you could provide me with answers to some of the technicalities of the subject that are puzzling me. Please feel free to provide links etc ….

    1. What sort of size is the primary (steel?) containment vessel? Height, diameter etc. What is the composition of the alloy it’s made of and how resistant is it to direct contact with hot nuclear fuel?

    2. How do the control rods interact with the fuel rods? I understand what both the fuel and control rods do, but how do they interact? What is there length, diameter etc? How many are there? Does a fissile reaction take place between separate fuel rods or inside them? If it’s inside them does that imply that the control rods are inserted inside the fuel rods? I’m struggling to get my head round this!

    3. What is the typical runtime of a nuclear reactor (commercial power generation) on a single fuel load? How long is the shutdown whilst a refueling takes place?

    4. What volume of water is passed through the reactor primary containment vessel during normal power generation? What’s the volume of water that’s drawn from the sea {or in some instances a river) for the cooling/condensing of the steam after it exits the turbines? Also, I understand the basic difference between a BWR and a PWR.

    5. On reactor start-up, how is the initial fissile reaction started? I understand the basics of nuclear fission chain reaction but how does it work in practice? What do the reactor operators do to the fuel and control rods to begin the initial fissile process?

    6. Finally …… what does it look like inside a reactor? I’ve seen lots of graphics and schematics on the web and in the news media but they are just that, drawings and pictures. Are there any actual pictures that show, in detail, the size and scale of the primary containment vessal and the fuel and control rods?

    Sorry for all the questions but I’m just trying to understand what’s going on. It’s a fascinating subject that will dominate the future debate on energy provision for years to come ( not that it hasn’t already! ) The comment and debate on this site is in stark contrast to the mainstream media which is obsessed with soundbites and sensationalism. To all of you, whether you are pro nuclear or against, I say this ….. keep talking ….. keep arguing ….. keep debating!

    Thankyou to all of you who have been willing to share your opinion.

    Kind regards.



  475. @paikea:

    i know that and it’s just funny that you feel for commenting on that, when there are a lot more other things to discuss.

    if you would have followed the comments you probably could have realised that this wasn’t the only thing i contributed here and as your remark is the only thing you wrote here.

    commenting on something that it is not important seems pretty important to you. i don’t get the logic here, but anyway.

    just check some posts i made before and maybe you can answer some of my questions. thanks.


  476. Tepco just said that in Reactor One 70% of the rods are damaged; in reactor Two it is one third. They don’t know in which though. Could mean they have holes (?) or the cores are about to melt.

    What does it mean if a rod got a hole?


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  478. sophia, on 16 March 2011 at 8:32 AM said:
    yes, you seem to take the technical portion pretty serious. i am not chastising your grammar. i just told you that the punctuation distracts from what you write. as you seem to comment on the technical portion how you write becomes a part of that, because people have to read it if they want to follow

    To criticise someone’s grammar in a response written quickly and then not use proper capitalization and punctuation yourself is the height of hypocrisy. I’m sure it was only because you were rushed.


  479. @William Fairholm:

    i didn’t criticise his grammar. that was his personal interpretation. i just was making a (probably not so) funny remark about his ‘power’ usage of exclamation marks (which you would have recognised if you would not just pick up a random post from somewhere and comment on it).

    it is amazing how this gets this part of the discussion all of a sudden. i have to ask you, Mr Fairholm, is this really all you have to contribute?

    (and as a english is not my mothertongue i wouldn’t dare to criticise someone’s grammar in my dreams…)


  480. I heard an expert on TVO Agenda program saying that the fresh water they are flying in by helicoptor is for the spent fuel pond. They do not want to pump seawater in there, as that would corrode the fuel bundles. Very limited containment for the spent fuel pond.


  481. im right in the middle of tokyo. ive done so many research among this topic and heard so many different informations…i truly dont know which information i should rely on, and i am very confused at this point. would anybody tell me if it is really true to stay in tokyo and be safe? we have detected 20 times as much radioactive materials in couple of places among tokyo. although the amount of radioactive materials at this point is said to be harmless to human, is it possible to say it will stay harmless tomorrow?


  482. Well, they have upgraded to INES 6 which puts Fukushima between Three Mile Island(5) and Chernobyl (7) on a scale of 1-7. http://hisz.rsoe.hu/alertmap/woalert_read.php?cid=29877 And I read an lovely bit of news that explains that Oehmer is a business scientists, NOT a Nuclear one. http://www.salon.com/news/japan_earthquake/?story=/news/feature/2011/03/15/japan_nuclear_reactor_fire

    You have to scroll down to find it. Title: Debunking a viral blog post on the nuke threat But this article he wrote that we have been discussing was posted before the meltdown happened, Oehmer is also not taking interviews.


  483. RE: “French Greens have anti-Nuclear field day « French News Online Newsroom”

    It’s really amazing how these spin masters just can’t let go of an idea. They keep repeating that the situation in Fukushima is not like Chernobyl. No joke!. As if the technical aspects of the event that causes the reactors operators to lose control of the reactor is somehow significant.

    This is basically a rehash of what GE has been saying about their reactors for year: “what happened at Chernobyl could not happen to GE reactor.” No joke! It was a different design. Something might and has happened.

    Indeed this piece also implies a piece of fiction about the Chernobyl accident. It implies that there was some specific flaw in the reactor that caused the reactor to go out of control. This is completely wrong. In fact the safety and control mechanisms of the plant operated perfectly well. What happened is that through a series of errors the plant operators deliberately created the accident themselves by making the reactor do things that caused the accident.

    They did not know they were doing these things, and the problems would likely not have occurred had the reactor staff had better instruction on the plants design, and if the regulations had been clearer. There was no malfunction at the plant caused by the design.

    The only real design flaw that might have helped in the Chernobyl situation was the use of an outer containment. An outer containment of the kind that has been blown off by hydrogen explosions at the GE plants at Fukushima. There is no reason to suspect that had the Chernobyl system had this outer containment, that the they too might have had a similar explosion inside it, after the initial accident.

    The people who built these Fukushima plant are no less guilty of making fundamental design errors than those who built the RMBK 1000 at Chernobyl.

    In fact, they apparently failed to take into account local environmental factors that were fundamental to this accident.

    1) The reactors were not designed to withstand the earthquake that occurred.

    2) The back up generators were not housed in an environment that protected them from massive amounts of water that might come into the plant as a result of a Tsunami caused by an earthquake.

    3) Their final line of defense, the battery power was not sufficient to run the plant through the entire cool down phase after the reactor was shut down, leaving the plant with what amounted to one and a half redundant power supplies for the reactors.

    There are other problems here that we could talk about, but the bottom line is that the possibility of a large earthquake creating a large tsunami was entirely predictable, and this indicates inadequate safety features at the plant, bad government supervision, and at the end of the day massive dereliction of duty by the companies that contracted the construction, and the contractors themselves, since these environmental factors were easily foreseeable.

    It seems they chose to ignore these factors, in more or less the same way that those who designed and built the RMBK at Chernobyl, decided to ignore the added safety features provided by an outer containment building.

    Saying that this event is “not like Chernobyl” on purely technical grounds amounts as an attempt to distract from the nature of the major nuclear accident that is unfolding.

    Ok, this is not like Chernobyl. So what?


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  485. Workers have now left the plant. Kyodo News reports that the very unspent and fully functional fuel rods that were being stored in the number 4 spent fuel pond have been exposed. They also note a reaction is not possible because these rods are contained in boron. What happens if the boron fails for some reason? Reports say this pond is burning, and possibly the source of the fire. Would this fire be spewing radioactive material into the air?


  486. Ok ,fine a 10″ pipe line can still be laid to a fresh water source.
    I’m pretty sure a seasoned crew can lay a mile or more in 24 hrs.
    We have done 3000 ft in 7 hrs.
    So with a crew working 24 hr shifts that’s 9000′
    But we had to have a crane to lift the pipe in place.
    Temporary is light weight no crane involved, so I say that production can be tripled easily.
    There no exclamation points!!!!!!
    They are also used when I am angry!
    And this situation could have been avoided if someone just used common sense.


  487. This is not like Chernobyl.
    It is a new Nuclear crisis, and with every crises comes a new set of problems.
    The case in Russia the core did not have a containment cell it should have had.
    Also you cannot knock the Reactor itself it has done everything it was supposed to do!
    The back up emergency system is the cause of this effect.
    That is all over.
    There is no need to try to save it anymore . Now is the time to contain it!


  488. thetrystero
    Have a look at http://www.peakoil.org.au/news/nuclear/BWR.design.gif which I have added an extra label to, indicating what I think is the Spent Fuel Pit. If they lose water to that and it boils dry, you get a Hydrogen fire that blows the roof off, and you should be able to see the exposed rods from a helicopter. Yes, the fire/explosion would be liberating all kinds of toxic/radioactive particles.

    And the water in the pits in #5 and #6 is heating up too. If water isn’t added, it might take hours or days or weeks to boil off. It probably wasn’t their first priority.


  489. If they are unable to cool the reactor cores what time-frame are we looking at for them to reach total melt-down? Also, should this happen and the fuel rods melt to the bottom of the containment vessel is there a time limit on how long the containment vessel will remain intact?


  490. 3 glaring mistakes by the engineers/scientists that designed this plant. whoever sanctioned the placement of all structures is also guilty.
    1. they placed a limit on what size earthquake nature could deliver.
    2. they anticipated small tsunamis only.
    3. they built the backup generators where they could be destroyed by a tsunami and failed to enclose them within an effective safe barrier.
    if this is the best that clever people can do then god help us all. obviously the politicians who approved it all are dumber than rocks.


  491. The exact condition of the core in reactors is not known as long as it can not be confirmed that all decay heat is removed safely from the core to the coolant in the containment and further on from the containment to the surroundings.

    Currently nobody knowns if this is the case, as all that is known is that fuel rods have been damaged, but it is not known if the core has remained in coolable geometry, or if it has melted partially forming a lumped mass, which is hard to cool completely (as in Three Mile Island). If the latter option has taken place, it will finally depend on durability of pressure vessel whether the accident will progress even further. In the Three Mile Island the pressure vessel remained intact even after the melt poured into the vessel bottom, although analyses carried out after the accident can not explain why.

    Should core damages in Fukushima progress to pressure vessel breach, it is very difficult to progress what will happen. In particular if the pressure vessel is ruptured in high system pressure, also the containment structure could be violently ruptured. The contaiment structure in Fukushima plant units is not designed for such loads.

    However, if the containement containing pressure vessel is flooded so that also pressure vessel is wetted from outside, it may remain intact even if the core has melted and the melt flows (or has already poured) into pressure vessel bottom. Chances for this increase as the time goes by, as the decay heat level decreases. However, there are control rod mechanisms that penatrate the pressure vessel bottom, and it is it very difficult to estimate how they would survive if molted core flooded the primary pressure vessel bottom. In this respect the design is very different from Three Mile Island, where there was no such penetrations in the primary pressure vessel bottom.


  492. Hi,

    Sorry but I think this is very wrong indeed:

    “For those who are reading this in Japan, the event is not over yet and the findings of airborne radioactivity plumes 100 mi. from shore and 30 km down from Fukushima are alarming – however they are not an emergency, especially if they are only the short-lived I-129 and 131”

    Iodine-129 is not short lived. It’s actually the opposite, all though not primodial it actually has a half life of 15.7 million years.



  493. Great summary of the events. But this only reinforces the fact that we cannot precisely predict everything in the world. Japan is the World’s most advanced nuclear nation, and regardless of how this all ends it is still clear that what was highly unlikely did in fact happen. Because highly unlikely things do.


  494. It doesn’t seem that the situation is improving, and despite adding sea water, it seems the temperatures are rising inside. The core, may or may not melt into a blob, and penetrate below the containment. Some kind of nuclear excursion, may or may not happen, but if it does it may spew whatever amount of radioactive material into the area, and into the atmosphere.

    One way or the other, they are just going to have to figure out how to bury the whole damn thing. Better sooner than later.


  495. Pingback: What, Exactly, Is a Meltdown and Is Fukushima the Next Chernobyl? | iTravelMags.com

  496. Pingback: The situation in Japan - some thoughts on Radiation

  497. Just seen this on BBC –

    “Following reports that several governments plan to reconsider their nuclear strategy after the events in Japan, science journalist Angela Saini tells the BBC World Service that this makes sense in seismically active zones. “But it would would just be reckless to throw energy policy up in the air because of an incident that affected one country, [it’s] almost freakishly rare for there to be an earthquake and a tsunami and for emergency services to be overwhelmed like that,” she says.”

    Now I sort of agree and think we need time to look at this, however events like this are not that rare even taken in context of 1000 years. Lisbon comes to mind:


    How about the possibility of a Tsunami generated from Iceland and effecting European sites. Are we able to cope with that at our installations?

    What is up with these people!!!!!!!


  498. It is amazing to see all the media prognosticators trying to “analyze” the severity of the situation going on at Fukushima. It would be one thing if CNN and FOX News would bring in nuclear physicists who have experience in plant design and operation, however most of these “analysts” have no qualifications whatsoever to be commenting on nuclear issues. None. Worse yet, the clueless, feckless media has been giving plenty of airtime to talking heads from political agenda groups who are masquerading as impartial “scientists.”


  499. Eric, there are plenty of retired physicists who would have excellent credentials to talk about the situation, and who have no obligations or present-day financial ties to the nuclear power industry, or conversely, for an anti-nuclear group with a special agenda. As a “normal person” myself, I have no problem with people taking an interest in the situation, such as yourself, and discussing the situation on this forum. The proper place for laypersons’ speculation is online forums, not national television by un- or under-qualified individuals, that’s all.


  500. The police have water cannon – it can accurately shoot a stream of water hundreds of feet – Gamma radiation is attenuated by water and the water’s depth was apparently too shallow to permit the helicopter to safely fly over and drop water. The water also would have been sea water and the water cannon may be able to use fresh since it has a self-contained tank of water on board. The sides of the pool also would be a good shield against the gamma radiation, whereas the lowered water level was not.


  501. Chris is correct, the media are parading a motley array of prognosticators and prophets before our eyes and, naturally enough, they are all disagreeing with each other. But, worse, even the people with apparently good credentials can’t seem to agree. The spectrum of opinions and after-the-fact ‘advice’ given right here also reflects this. Reactor physics is pretty complex and I begin to suspect that a lot who work in the field don’t fully understand their profession. So how can the public have confidence in the nuclear industry?


  502. Steviesmyths

    “Some kind of nuclear excursion, may or may not happen”

    Are you saying that fission may be the predominant source of heat in the case of a molten blob – and then, again, it may not?

    This is such a fundamental question, with such huge implications, that I would be horrified if it is truly an unknown.


  503. Folks: some of you may have seen Robert Alvarez very scary spent fuel pool scenario. He makes it sound like Chernobyl will be nothing compared to this.

    On alvarez and chernobyl, alvarez claims that the reactor core released 6 million curies. Not quite right. It released 300 million curies, half of which were xenon 133, inert gas, much of the rest the more dangerous iodine 131 and Cesium 137. Info from Garwin and Charpak, Megawatts and Megatons.

    How wrong can you be in the service of creating fear?

    Or am i wrong about something?


  504. The radiation monitoring system around the plant is down apparently due to power outage. Could be I suppose. Maybe battery backup is a consideration in these circumstances. I would have thought radiation monitoring would be one of the most important requirements for the authorities.


  505. Chris. Scientists also have opinions. Indeed, some of them have opinions and then do things like join the anti-nuclear lobby. Its a kind of weird inversion to think that once they join the anti-nuclear lobby that they then represent an “agenda” that doesn’t have anything to do with their scientific appraisal of the value of nuclear power. The same is true of those scientist who support nuclear power — they think it is safe, or at least safe enough.

    Some scientists are in-between, they think nuclear power would be safe, if implemented differently. You just aren’t going to find a lot of informed people who don’t have an opinion on the subject. I don’t see where this idea that informed people should not have opinions comes from.

    It is their study and research that informs their opinion. Dollars to donuts almost any working scientist who supports nuclear power has a job in the nuclear industry, somewhere, and any working nuclear physicist who doesn’t have a job in the nuclear industry, doesn’t have that job because they don’t support nuclear power — likely they support groups, or work with groups that are against it.

    You have it backwards, they are not fronting for an agenda, the agenda is formed from their opinions, based on their research and analysis.

    Other than that, if you don’t like CNN, stop watching it. There are plenty of news sources out there. My first exposure to this event was through Russia Today, and they featured a rather pale faced, nuclear scientist working in the Tokyo area, who said nothing reassuring, or definitive — that is part of the problem with scientists, they just don’t fit the American media mold. He spoke in detail, in a very abstract way about this event, from a technical point of view, and laid out numerous possibilities, from the worst to the best, but, (and this is an important point) any scientist worth his salt, who is not directly in the loop, is not likely to give a firm opinion about outcomes in this case, because it is simply too difficult to come to a firm conclusion based on the very scant information that is available publicly.

    It is possible to make conjecture of course, but too much conjecture from a position of authority can be irresponsible from a professional point of view.


  506. Gregory. I don’t get your point. You are saying Alvarez was attempting to foment fear by understating the severity of the release of radiation from the plant?

    Events are moving quickly, at the time that Alvarez originally wrote his article, bringing attention to the spent fuel pool issue long before it became current in the media, the release from the reactor may have only been 6 million curries.

    It may now be a total much higher than that as described by your source.

    As for the threat of the spent fuel rods, numerous scientists confirm the problem here. It is quite simple to understand if you think about it this way: A lot of people have been talking about the importance of keeping the fuel rods inside the containment from being exposed in an uncontrolled environment. In fact, GE went through considerable effort to ensure that they were sealed within three different containments.

    The spent fuel rods in the spent-fuel pool are not in a containment at all, the containment having been blown off by a hydrogen explosion.

    Hence, neither TEPCO nor the Japanese government seems as sanguine as you are about the issue of the spent-fuel pools.


  507. stevesmyths:

    The spent fuel cells in the pools were never in any containment. The containment system only exists around the reactor. I believe that the hydrogen explosions have destroyed some of the buildings that were outside the containment vessels.


  508. Stupid question on the original article: If there is no hydrogen in the plant it won’t explode and therefore not spread around radioactive material? Is that correct? If so, why not let (from a certain point) let the reactor fall dry and have all that radioactive stuff nicely accumulated lying in the containment – or down in the earth? Wouldn’t do big damage, I guess.


  509. Can someone help me with the math? The latest report from JAIF says that the radiation level is 1937 micro sieverts.

    The chart a commenter elsewhere linked to:

    is in milli sieverts.

    As a resident of the Denver area, it says I get 1.8 milli sieverts a year from background radiation.

    According to Wikipedia, the conversion is 1000 mSv = 1,000,000 milli sievert.

    So the workers are exposed to about a year’s worth, right?


  510. Whatever the final outcome at Fukushima Daiichi, and let’s remember it’s the only plant that got swamped by the tsunami, and all of the other 49 reactors in Japan have not been catastrophically damaged by the earthquake, this event is not the ‘death of the nuclear industry’.

    If Chernobyl did not stop the development of better and safer nuclear reactors, then I seriously doubt this tragedy will either. What one could safely assume is that reactors will no longer be sited anywhere that’s just some metres above sea level if they are in a region like Japan.

    As horrible as this event is, we still need to look at the real causes and make better judgments about managing risk, but blaming the reactor design seems a bit odd when it was never designed to withstand being flooded by the ocean.


  511. Typical MSM and PPS for political gain!
    Worst case scenario and jam nuclear power.
    once again i will say the reactor did it;s job and was safe until the backup coolant sys failed.
    It’s like paying your baby sitter to watch your kids and the house burns down!


  512. @Common Sense, on 17 March 2011 at 7:46 AM

    1937 microsieverts (μSv) is equal to 1.937 millisieverts (mSv)

    Technically this a dose, not a level. The report will almost certainly have been 1937 microsieverts per hour.

    Residents of Denver get 3.2 mSv natural exposure per year, compared to national average of 2.4 mSv

    So the worker’s dose depend on how long they stay in the area that has high levels, what form of radiation it is and whether their protective gear is suitable for that exposure. You can be pretty sure they’re all breathing filtered air with full body cover. So their actual dose will be much lower than an open-air environmental reading would suggest.