Hot News Nuclear

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:

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.

By Barry Brook

Barry Brook is an ARC Laureate Fellow and Chair of Environmental Sustainability at the University of Tasmania. He researches global change, ecology and energy.

874 replies on “Fukushima Nuclear Accident – a simple and accurate explanation”

@ 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.


It’s hard to believe that this event will end well when one of the reactors is now in flames and the staff of the entire facility seems to have fled.


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 ?


“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]


[…] … Fukushima Nuclear Accident – a simple and accurate explanation « BraveNewClimate This entry was posted in Uncategorized. Bookmark the permalink. ← Breathing LikeBe the […]


Many many thanks for a thorough and easily read explanation of the situation.
This is more or less the first and only thing all of the media should have sent.
Thanks again!


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.


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.


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.


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.


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.


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!


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


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’.


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.


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”.


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.


Thanks to the author for the updates, the situation is very worrying. I noticed you took down your conclusion that “the plant is safe now and will stay safe,” a necessary step for an objective scientist.


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.


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.


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.


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]


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.


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.


What is the material of the Reactor Shield? Steel or Stainless Steel?

Also, Is the inner skin of the thick strong concrete containment ordinary steel or Stainless Steel ??


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.


“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?


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…


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.”


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.


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….



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.


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?


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?


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! =)


@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.


[…] The reactors in Fukushima are of the second most popular type in the world: Boiling Water Reactor. You must understand that there is no more Nuclear Chain Reaction taking place inside the reactors. However a nuclear reactor is not an electric appliance that you can just unplug. After the chain reaction stops, some elements inside the reactor start decaying, some decay fast (like seconds), others – slower. It is important to note that many of these fission products produce heat while decaying. This means that gradually they will cool down after the stop decaying. For more information on reactor physics, read here. […]


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.


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.


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!!!!!!!


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.


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.


JD# 5:27
‘those generators can power 8 to 10 in pumps with a temporary pipeline’

Or you could just call the local fire department and have them hook up a pumper truck.


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 !


Radioactive Items at an intolerable rate lasts forever!!!!!!!!!!!!
You might drill in to the Earths core and burn it off that way!


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.


[…] Fukushima Nuclear Accident – a simple and accurate explanation (via BraveNewClimate) Posted on March 15, 2011 by observadordomundo Twitter updates: @BraveNewClimate New 15 March: Fukushima Nuclear Accident – 15 March summary of situation New 14 March: Updates 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 2):(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 … Read More […]



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.


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?


Pumper truck would be good also but i was thinking
volume of water!
A 10″ line can deliver 47,000 gal. water per minute!!!


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!!!!!!!


The experts got a bit silent.

What is your analysis of the situation right now?

There’s not much happening just now. The MSM is busy recycling alarmism from yesterday.


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!!!!!!


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. :-(


Leave a Reply (Markdown is enabled)

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s