Hot News Nuclear

Fukushima Nuclear Accident – 15 March summary of situation

The situation surrounding the Fukushima Nuclear Accident, triggered by Japan’s largest recorded earthquake and the resulting 10 m high tsunami, continues to develop rapidly. This post is intended to be a concise update of the situation as of 12pm Japan Standard Time, 15 March 2011. For a summary of the situation prior to today, read these posts:

Japanese nuclear reactors and the 11 March 2011 earthquake

Fukushima Nuclear Accident – a simple and accurate explanation (with further updates at MIT here:

Japan Nuclear Situation – 14 March updates

Further technical information on Fukushima reactors

TEPCO reactor by reactor status report at Fukushima

This is also a useful summary, from William Tucker (published in the Wall Street Journal): Japan Does Not Face Another Chernobyl. See also:  Nuclear Overreactions: Modern life requires learning from disasters, not fleeing all risk.


Attention has centred on units #1, 2 and 3 of the Fukushima Daiichi plant (all Boiling Water Reactors built in the 1970s). Current concern is focused on unit #2 (more below). Units 4, 5 and 6 at the site were not in service at the time of the earthquake and their situation is stable.

At a nearby plant, Fukushima Daiini, the situation is now under control, and units are in, or approaching, cold shutdown. I do not expect any further significant developments at that site. To quote WNN:

In the last 48 hours, Tepco (Tokyo Electric Power Company) has carried out repairs to the emergency core coolant systems of units 1, 2 and 4 and one by one these have come back into action. Unit 1 announced cold shutdown at 1.24 am today and unit 2 followed at 3.52 am. Repairs at unit 4 are now complete and Tepco said that gradual temperature reduction started at 3.42pm. An evacuation zone extends to ten kilometres around the plant, but this is expected to be rescinded when all four units are verified as stable in cold shutdown conditions.

Fukushima Daini Unit 1 reactor

o As of 1:24AM on March 14, TEPCO commenced the cooling process after the pumping system was restored.

o At 10:15AM on March 14, TEPCO confirmed that the average water temperature held constant below 212 degrees Fahrenheit.

Fukushima Daini Unit 2 reactor

o At 7:13AM on March 14, TEPCO commenced the cooling process.

o As of 3:52PM on March 14, the cooling function was restored and the core temperature was stabilized below 212 degrees Fahrenheit.

• Fukushima Daini Unit 3 reactor

o As of 12:15PM on March 13, reactor has been cooled down and stabilized.

• Fukushima Daini Unit 4 reactor

o At 3:42PM on March 14, cooling of the reactor commenced, with TEPCO engineers working to achieve cold shutdown.

The rest of this post will focus on the ongoing crisis situation at Fukushim Daiichi. Let me underscore the fact that accurate information is sparse, uncertain and rapidly changing.

During March 12 and 13, there were serious issues with providing sufficient cooling to units 1 and 3 after the tsunami had caused damage to the diesel backup generators and compromised the emergency cooling water supply. This resulted in a decision to use sea water injection to keep the reactors cool — a process that is ongoing. Steam was regularly vented as part of the effort to relieve steam pressure within the reactor vessels, but this also led to an accumulation of hydrogen gas within the secondary buildings that house the reactor units. Possible sources for the hydrogen are discussed here. Unfortunately, this hydrogen could not be vented sufficiently quickly, resulting in chemical explosions (hydrogen-oxygen interactions) within the two reactor housing buildings of both unit 1 and unit 2 during March 12-13.

The roof and part of the side walls of both buildings were severely damaged as a result. After the first hydrogen explosion there is no longer a roof on the building, so there is little chance of any large buildup of hydrogen or further explosions at these units. [In restrospect, the designers (40 years ago) perhaps should have more carefully considered the implications of the decision to vent the pressure suppression torus to the reactor building space]. Although hydrogen recombiners are a standard feature of that design, they unfortunately lost all AC power, and then the batteries were run down. Containment (the robust concrete shell and 18 inch thick steel reactor vessel within it), however, remained intact. This was verified by monitoring levels of radiation surrounding the units — if there had been any containment breach, levels would have jumped.

This cutaway diagram shows the central reactor vessel, thick concrete containment and lower torus structure in a typical boiling water reactor of the same era as Fukushima Daiichi 2

This is an overview of the current status of units 1 to 3:

Radiation Levels

o At 9:37AM (JST) on March 14, a radiation level of 3130 micro sievert was recorded at the Fukushima Daiichi Nuclear Power Station.

o At 10:35AM on March 14, a radiation level of 326 micro sievert was recorded at the Fukushima Daiichi Nuclear Power Station.

o Most recently, at 2:30PM on March 15, a radiation level of 231 micro sievert was recorded at Fukushima Daiichi Nuclear Power Station.

Fukushima Daiichi Unit 1 reactor

o As of 12:00AM on March 15, the injection of seawater continues into the primary containment vessel.

Fukushima Daiichi Unit 2 reactor

o At 12:00PM on March 14, in response to lower water levels, TEPCO began preparations for injecting seawater into the reactor core.

o At 5:16PM on March 14, the water level in the reactor core covered the top of the fuel rods.

o At 6:20PM on March 14, TEPCO began to inject seawater into the reactor core.

o For a short time around 6:22PM on March 14, the water level inside the reactor core fell below the lower measuring range of the gauge. As a result, TEPCO believes that the fuel rods in the reactor core might have been fully exposed.

o At 7:54PM on March 14, engineers confirmed that the gauge recorded the injection of seawater into the reactor core.

o At 8:37PM on March 14, in order to alleviate the buildup of pressure, slightly radioactive vapor, that posed no health threat, was passed through a filtration system and emitted outside via a ventilation stack from Fukushima Daiichi Unit 2 reactor vessel.

Fukushima Daiichi Unit 3 reactor

o At 11:01AM on March 14, an explosion occurred at Fukushima Daiichi Unit 3 reactor damaging the roof of the secondary containment building. Caused by the interaction of hydrogen and oxygen vapor, in a fashion to Unit 1 reactor, the explosion did not damage the primary containment vessel or the reactor core.

o As of 12:38AM (JST) on March 15, the injection of seawater has been suspended.

What is of most current concern?

Units 1 and 3: the situation now seems fairly stable. There is some concern that holding pools for spent nuclear fuel (SNF) may have been damaged by the hydrogen explosions, but nothing is confirmed. Provided the pool walls remain unbreached and the SNF is covered with water, the situation should not escalate. Note: Although still ‘hot’, the SNF decay heat is many orders of magnitude lower than the fuel assemblies within reactors 1 to 3.

Unit 4: A fire has started at the building of Unit #4. Note that the reactor of this unit is stable and was not operating at the time of the earthquake.

Kan also confirmed a fire burning at unit 4, which, according to all official sources, had never been a safety concern since the earthquake. This reactor was closed for periodic inspections when the earthquake and tsunami hit, therefore did not undergo a rapid and sudden shutdown. It was of course violently shaken and subject to the tsunami.

Shikata said that there had been “a sign of leakage” while firefighters were at work, “but we have found out the fuel is not causing the fire.” The fire is now reported extinguished.

Unit 2: This is now of most concern, and the situation continues to change quickly. Here is the key information to hand (I will update as new data emerges).

Loud noises were heard at Fukushima Daiichi 2 at 6.10am this morning. A major component beneath the reactor is confirmed to be damaged. Evacuation to 20 kilometres is being completed, while a fire on site has now been put out.

Confirmation of loud sounds at unit 2 this morning came from the Nuclear and Industrial Safety Agency (NISA). It noted that “the suppression chamber may be damaged.” It is not clear that the sounds were explosions.

The pressure in the pool was seen to decrease from three atmospheres to one atmosphere after the noise, suggesting possible damage. Radiation levels on the edge of the plant compound briefly spiked at 8217 microsieverts per hour but later fell to about a third that.

A close watch is being kept on the radiation levels to ascertain the status of containment. As a precaution Tokyo Electric Power Company has evacuated all non-essential personnel from the unit. The company’s engineers continue to pump seawater into the reactor pressure vessel in an effort to cool it.

Evacuation ordered

Prime minister Naoto Kan has requested that evacuation from 20 kilometer radius is completed and those between 20-30 kilometers should stay indoors. He said his advice related to the overall picture of safety developments at Fukushima Daiichi, rather than those at any individual reactor unit.

Shortly afterwards Noriyuki Shikata said radiation levels near the reactors had reached levels that would affect human health. It is thought that the fire had been the major source of radiation.

Prime minister Naoto Kan has requested that everyone withdraw from a 30 kilometer evacuation zone around the nuclear power plant and that people that stay within remain indoors. He said his advice related to the overall picture of safety developments at Fukushima Daiichi, rather than those at any individual reactor unit.

Regarding radiation levels: It is very important to distinguish between doses from the venting of noble-gas fission products, which rapidly dissipate and cause no long-term contamination or ingestion hazard, and aerosols of other fission products including cesium and iodine.

From NEI:

Yukio Edano, Japan’s Chief Cabinet Secretary, during a live press conference at 10 p.m. EDT, said there is a fire at Fukushima Daiichi 4 that is accompanied by high levels of radiation between Units 3 and 4 at the site. The fire began burning at Unit 4 at around 6 a.m. Japan time on March 14 and is still burning. Fire fighters are responding to the fire. The reactor does not have fuel in the reactor, but there is spent fuel in the reactor (pool) and Edano said that he assumes radioactive substances are being released. “The substances are coming out from the No. 4 reactor and we are making the utmost effort to put out the first and also cool down the No. 4 reactor (pool).”

Edano said that a blast was heard this morning at Unit 2 at about 6:30 a.m. A hole was observed in the number 2 reactor and he said there is very little possibility that an explosion will occur at Unit 2.

“The part of the suppression chamber seems to have caused the blast,” Edano said. A small amount of radioactive substance seems to have been released to the outside.

TEPCO workers continue to pump sea water at 1, 2 and 3 reactors. “The biggest problem is how to maintain the cooling and how to contain the fire at No. 4.” At 10:22 a.m. Japan time, the radiation level between units 2 and 3 were as high as 40 rem per hour. “We are talking about levels that can impact human health.” Edano said.

Of the 800 staff that remained at the power plant, all but 50 who are directly involved in pumping water into the reactor have been evacuated.

More updates to the above as the fog of uncertainty begins to clear…


Finally, a telling comment from a friend of mine in the US nuclear research community:

The lesson so far: Japan suffered an earthquake and tsunami of unprecedented proportion that has caused unbelievable damage to every part of their infrastructure, and death of very large numbers of people. The media have chosen to report the damage to a nuclear plant which was, and still is, unlikely to harm anyone. We won’t know for sure, of course, until the last measure to assure cooling is put in place, but that’s the likely outcome. You’d never know it from the parade of interested anti-nuclear activists identified as “nuclear experts” on TV.

From the early morning Saturday nuclear activists were on TV labelling this ‘the third worst nuclear accident ever’. This was no accident, this was damage caused by truly one of the worst of earthquakes and tsunamis ever. (The reported sweeping away of four entire trains, including a bullet train which apparently disappeared without a trace, was not labelled “the third worst train accident ever.”) An example of the reporting: A fellow from one of the universities, and I didn’t note which one, obviously an engineer and a knowlegable one, was asked a question and began to explain quite sensibly what was likely. He was cut off after about a minute, maybe less, and an anti-nuke, very glib, and very poorly informed, was brought on. With ponderous solemnity, he then made one outrageous and incorrect statement after another. He was so good at it they held him over for another segment

The second lesson is to the engineers: We all know that the water reactor has one principal characteristic when it shuts down that has to be looked after. It must have water to flow around the fuel rods and be able to inject it into the reactor if some is lost by a sticking relief valve or from any other cause – for this, it must have backup power to power the pumps and injection systems.

The designers apparently could not imagine a tsunami of these proportions and the backup power — remember, the plants themselves produce power, power is brought in by multiple outside power lines, there are banks of diesels to produce backup power, and finally, banks of batteries to back that up, all were disabled. There’s still a lot the operators can do, did and are doing. But reactors were damaged and may not have needed to be even by this unthinkable earthquake if they had designed the backup power systems to be impregnable, not an impossible thing for an engineer to do. So we have damage that probably could have been avoided, and reporting of almost stunning inaccuracy and ignorance.Still, the odds are that no one will be hurt from radioactivity — a few workers from falling or in the hydrogen explosions, but tiny on the scale of the damage and killing around it.

It seems pathetic that Russia should be the only reported adult in this — they’re quoted as saying “Of course our nuclear program is not going to be affected by an earthquake in Japan.” Japan has earthquakes. But perhaps it will be, if the noise is loud enough.

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.

378 replies on “Fukushima Nuclear Accident – 15 March summary of situation”

Yomiuri is rePorting the fire is out as of 6:15 and they are still unable to confirm what burnt because radiation levels are/were to high


The report then goes on to say that they are still deciding on how they are going to deliver water to the spent fuel pools


Does anybody know when it had been planned (before earthquake) for reactor 4 be restarted?

Where are new fuel rods stored before loading into the core?


“Tokyo Electric Power has estimated the extent of small holes or cracks in the fuel rods, based on the amount of radioactive material in the coolant.

It says 43 percent of the fuel rods in the No.1 reactor were possibly damaged at 1 PM on Tuesday, but the ratio had increased to 70 percent by 3:25 PM.
At the No.2 reactor, the ratio rose to 33 percent from 14.”


There is a deep trench right off shore. A reasonable idea is to grapple the rods and dump them in the ocean over the trench.

If the roof is in the way, the a couple of well-placed smart bombs could take care of that.

It’s supremely ironic that the one real, intractable problem that has arisen involves the nuclear waste, the thing nobody ever wants to deal with :(



Timestamps showing up now on the NHK stories:

Fire breaks out again at No.2 reactor

Tokyo Electric Power says the building of the No.4 reactor at the Fukushima Daiichi nuclear power plant is on fire again. Nobody was injured.

The company said at a press conference that the fire was confirmed at 5:45 AM on Wednesday. It says the northwestern corner of the 4th floor, which was on fire on Tuesday, has caught fire again. This is where the pump used to put water into the reactor is located.

TEPCO has requested firefighters. It said workers cannot reach the fire due to the high level of radioactivity at the site.

The No.4 reactor caught fire at 9 AM on Tuesday. TEPCO said the first fire extinguished itself.

Wednesday, March 16, 2011 07:46 +0900 (JST)
That’s recent news. At the moment I’m writing this, it’s Wednesday 9:55 am in Tokyo:


“URGENT: Spraying boracic acid eyed to prevent recriticality at No. 4 reactor

TOKYO, March 16, Kyodo

Tokyo Electric Power Co. said Wednesday it is considering spraying boracic acid by helicopter to prevent spent nuclear fuel rods from reaching criticality again, restarting a chain reaction, at the troubled No. 4 reactor of its quake-hit Fukushima No. 1 nuclear power plant.

”The possibility of recriticality is not zero,” TEPCO said as it announced the envisaged step against a possible fall in water levels in a pool storing the rods that would leave them exposed. ”


When they are talking about the possibility of “recriticality” of spent fuel, it doesn’t sound at all good.

Spent fuel is already stored in borated steel boxes to prevent a rise in activity, so if they are considering adding of boracic acid to the pool water, the only logical conclusion is that they suspect physical damage to the rods at such extent, that the normal protection against restarting of fission is compromised.


@American “Just my lay opinion, but it seems to me that the people to be most respected on this issue right now are saying that they just simply flat don’t know what the real fundamental situation is, nor know all of what might further happen, nor how (further) bad it might get, period. And that any confident forecast, regardless of same being either optimistic or pessimistic, is just smoke, pure and simple.”
A bit of perspective is required here. There has been a massive earthquake and tsunami that killed more than 10,000 people, injured tens of thousands of others and displaced hundreds of thousands if not millions as well massively destroyed infrastructure.

At the same time we have the nuclear reactor damage where not a single person has been killed or injured by radiation.

The situation is bad at the reactor and we all hope environmental contamination is kept to the absolute minimum. But let’s keep perspective. Not a single human killed or injured by radiation is a success considering the circumstances.


NHK now shows helicopter footage 30 km away from Fukushima Daiichi, showing billowing white/light grey smoke issuing in large amounts from what appears to be the reactor 4 building.


> Red_Blue
> recriticality … borated steel boxes … boracic acid …
> only logical …

That’s not the only logical conclusion, and we don’t know yet. You’re not using facts; where are you getting your information, why do you consider it a reliable source? Someone posted much the same notion yesterday or the day before and it was debunked then.

Fission isn’t “on” or “off” — it’s happening, and more will happen if the fuel gets too close together. But it sounds like you’re–just like the guy earlier, in fact–confusing “criticality” with a chain reaction or “prompt critical” event. This is not that. Look it up.

See the Powerpoint files linked earlier for accurate descriptions of how the fuel is stored to keep the rods separate at specified distances suitable for active cooling. If the supporting racks fail, the rods fall closer together and heat up, both from increased fission and decay heat, and the metal can burn and fuel melt.

NHK: White smoke billowing, “a constant stream of smoke” — video from a long lens on a helicopter 30 km away from the plant


>> Red_Blue
>> recriticality … borated steel boxes … boracic acid …
>> only logical …

>That’s not the only logical conclusion, and we don’t know yet.
> You’re yot using facts; where are you getting your information

Oh, good grief, I finally got that page to open and I apologize, you really are quoting from tagged “Urgent”

It’s garbled.
— There’s no such thing as “boracic acid”
— the helicopter idea was talked about and dismissed hours ago.
— I haven’t yet down the “recriticality” term — it has to be someone mangling a translation from the Japanese to English.

They’re confusing people. It’s a real, big worry. Mangling the info isn’t helping.

Anyone know where the TEPCO original source for that is?

Once someone gets a sample of that smoke, we’ll know what’s burning.

Ugly, and there are no good possibilities for this.


“Not a single human killed or injured by radiation is a success considering the circumstances.”

This is still evolving. And a major radiological accident could leave more than 10,000 with life long problems.


“Not a single human killed or injured by radiation is a success considering the circumstances.”

That’s a pretty dim view on what could be considered “injury by radiation”. I don’t think you would want to make that argument for example in an insurance court against a claimant who has received a 100 mSv dose, for which there is solid evidence of (rather small ofcourse) cancer risk increase. There are now at least two such cases of plant operators known, but many more could be unreported due to other injuries.


Smoke shown from the helicopter was “about 10am Japan time” — it’s now a bit after 11am Japan time, and the later report on line says there are no more flames. So NHK is running behind the news and they are continuing to replay old tapes. It’s hard to tell what’s current and what’s old on their screen , as their replays have the same “breaking news” tag.


Jeff in Dallas wrote,
“At the same time we have the nuclear reactor damage where not a single person has been killed or injured by radiation.

The situation is bad at the reactor and we all hope environmental contamination is kept to the absolute minimum. But let’s keep perspective. Not a single human killed or injured by radiation is a success considering the circumstances.”

Oh come now, this statement borders on the absurd. The mechanisms of injury and death are completely separate in each case, with the consequences of earthquake and tsunami damage obvious and immediate, and the consequences of radiation damage usually chronic, cumulative, and slow to develop. Yours is an apples-to-spacecraft comparison.

I’m all for a rational, measured, fact-based approach, and I’m absolutely opposed to “fear-mongering”…But comparing earthquake and tsunami death tolls to deaths as a result of this situation is an inadequate metric, to say the least.


Jeff in Dallas, neither you nor anybody can say that there have been no radiation injuries from the reactors. Radiation has been released. People have been exposed. That is all we know.

That said, you are correct that the known casualties are perhaps two workers who are missing, certainly less than the casualties we see from coal mining operations. But the timeline for nuclear casualties is a helluva lot longer than the one for any other energy production process. It is measured in generations, not days.


I recommend putting a “world clock” window up for anyone quoting comments and checking when what you see or read actually happened. NHK TV’s “live stream” right now shows both 05:00 and 06:11 at different places, and the actual Tokyo time is 11:11AM. Be wary, it’s easy to be fooled by all the “live” banners.


@Mike and Red_Blue, goodrich4bk

Three Mile Island accident in the US, worst Nuclear plant accident on US soil, similar in some ways to the current event. In that case, no deaths, no increased cancer incidence in the vicinity even after 30 years of monitoring. Yes, we’ll have to wait and see, but so far only two deaths (reported missing) attributed to the tsunami, not radiation.

I’m just saying that before anyone can call this a disaster considereing the grand scope of things in that area now, there has to at least be an injury. So far, there has not. And TMI incident tells us there very well may not be, even 30 years down the road.


“Anyone know where the TEPCO original source for that is?”
TEPCO no longer releases any data about the Daiichi reactors in its own site, the latest data is about the shut down Daini reactors and almost a day old. The same applies to NISA. JAIF has released updates every few hours, but the latest is 16 hours old. FEPC Washington office puts out a release couple times a day, latest being 12 hours old.

“Fission isn’t “on” or “off” — it’s happening, and more will happen if the fuel gets too close together.”

There is no significant fission going on in the spent fuel rods of an intact storage pool, most of the decay reactions (as beta decay and low energy alpha decay) are incapable of causing fission in the irradiated fuel. The other rare exception is spontaneous fission, but this is also irrelevant. In any case, the insignificant fraction that happens, happens in the same rod. The spacing and the racks make sure of that.

The reason why a reactor works in the first place, is that it has a large amount of that fuel in close proximity with moderator instead of neutron absorber (as there is in the spent fuel rod pool) between the rods.


Sorry those who objected, your info on nat gas and your interpretation (or reinterpretation, I should say) of my suggestions are incorrect. My apologies if my sentence formulation was at fault.

Nat gas is better *than coal*. And *oil.* It’s safer *than coal* and safer *than nukes.* (Note the word “than.”)

Solar and wind are fine long-term but they are not cost-effective nor as ubiquitous as NG for *now*, nor can we export it. Not as much use from solar as NG in Detroit or Seattle where they average 180-220 cloudy days per year. (For *now*.)

We just made the largest oil and NG find in US history. Why not use it? Thinking real-world for the next five to ten years, not Tomorrowland nor Fantasyland.

Use NG *WHILE* WEANING OFF OIL and WHILE making the transition to other alternatives. (Whether it’s solar, wind or cat urine. But not corn. Burning food for fuel is D-U-M.)

People have died falling off of windmills, being clobbered by solar panels too, and have become sick and had industrial accidents making them, but it doesn’t mean I don’t support them as alternatives. Heck, cars have killed MANY more people than nat gas, nuclear energy, coal mining, solar and wind put together, but it doesn’t affect the argument about what to use to power them. If you wanna go that route, let’s just shoot all the cars into space and go back to sandals.

I’d rather be civil, reasonable and realistic. Hopefully you do too. Thanks!


Short reports from the most recent new conference (via Kyodo, times JST):
# NEWS ADVISORY: Seawater injection into No.4 reactor via helicopter too risky: Edano (11:39)
# BREAKING NEWS: Water injection into No.4 reactor has yet to begin: Edano (11:34)
# BREAKING NEWS: Containment vessels of No.1, No.3 reactors may be damaged: Edano (11:30)
# BREAKING NEWS: Radiation levels at Fukushima plant rose after 10 a.m.: Edano (11:23)
# NEWS ADVISORY: TEPCO can’t check smoke at Fukushima plant as radiation is too high (11:16)


About my accused “dim” view, I have studied nuclear engineering and radiological health engineering at Texas A&M (although my degree is in chemistry). I understand radiation effects, the Q value for different types of radiation, ALARA principle, units of radiation Curies/rems/rads/Sieverts. I understand reactor physics and geometry, eigenvalues solutions and neutron flux as it relates to reactor criticality. A lot of that doesn’t apply in a situation like this because you can’t possibly know the neutron flux or moderation or lethargy that may lead to U-235 fission reactions. My perspective may be different than others, but I’m not “dim” or a layperson on this subject.


Rats; unfortunately there’s no “edit” button for posts. I meant to type “possibly” the largest oil & ng find.

Also, if you’re that worried about CO2 and methane emissions into the atmosphere, we should also get rid of all the people and animals who do all that darn exhaling and farting. ;-)


MikeP, on 16 March 2011 at 1:32 PM, & Alex, on 16 March 2011 at 1:36 PM — Could we please stay on topic? Gneral commentary can go to Open Thread 9. Thank you.


How many bananas is a milli-sievert vs. a Mega-sievert? And why don’t they release the official statistics in bananas?


If I read the recent IAEA March 15 18:00 GMT update correctly, the reactor fuel for units 5 and 6 remain inside the reactors, not in the spent fuel pool. Only unit 4’s fuel is in the spent fuel pool. Maybe a little break.


R4 was shut down when the quake hit and, as I understand it, ‘the main reactor was not fueled.’ Do they exchange ALL the fuel at once? (I though they staggered refueling.) Did the spent fuel on the roof just recently come out of the reactor? If so, it’s about as hot as it comes. This might explain the apparently rapid boil-off of the cooling pool.


a correction to my 2:44 PM post above: Oyster Pt is a BWR/2 design with 5 recirculation loops on the reactor. Its 619 MWe. Fukushima 1 is a BWR/3 460 MWe design with 2 recirculation pumps (with internal jet pumps for more eff), instead of 5. Otherwise, I think the two plants are very close in design, only 2 years apart, so the drawing should be good.


For those interested, the reactor design pressure is 1250 psig and the drywell/torus design pressure is ~60 psig.


David, I’m happy to stay on topic as long as the others are. I even promise not to quote Kipling. ;-)

Any further info on 5 and 6?

Thank you!


Its not the probability or even the possibility of a nuclear reactor disaster that drives a “lay” person’s opinion of the use of nuclear power, we know there is risk in everything in life. The problem is geographic SCALE.

When a nuclear power plant that some politician and his bureaucrats put on an earthquake fault proves that their statistician’s “probability report” was wrong, the SCALE of a resulting disaster is what is considered.

Why is that? Its because of human nature. The widespread area and magnitude of such a disaster is too much for a human soul to manage and so we want to avoid it. Sure, more people die in auto accidents etc, than will ever die in a nuclear power plant disaster, that is a fact… but those tragedies happen in a way that is manageable to human beings on whole. The scale is different.

In Japan, at this moment, a human being is trying to survive a cold dark night, limited food, shelter, the the loss of loved ones and many friends. All around them is disaster as far and wide as they can see. In their realization of having survived is the realization that all around them hundreds if not thousands of others lie buried where they did not.

Hopefully they are finding within themselves and others around them, that resilience that pulls human beings through such events…but the SCALE of such a tragedy is something any sane person will always want to avoid.

Thus, even though it was a natural event, an earthquake and tsunami that created this nightmare, we have no control over these things and so we see the nuclear power plants as similar in their ability to cause something of this scale, but something that we can control…and thus the focus on them and the worst case scenario.


The situation seems to be getting worse than what could reasonably have been expected on Sunday. Could it not be that TEPCO was less than forthcoming with information?

According to the NYTimes article below, a Japanese nuclear power executive (not with TEPCO) claimes anonymously that there was damage to the spent fuel pool in unit 2.

While the veracity is hard to confirm, it seems very difficult to understand how they could not have been more vigilant on problems with the pool in unit 4.

Shouldn’t they also have removed some of the side walls before they blew off in explosions, since they couldn’t evacuate hydrogen through pumps?

I understand that it’s a very trying task (though can’t image how much so), but some poor choices seem to have deteriorated conditions. In hindsight, perhaps given total blackout, operators should have accepted certain, manageable actions to risking structural integrity.


Thank you for providing a clear overview on this. As an engineer myself it does depress me that the failures here have been with the simple parts of the system, that many of us could have got right. As for not imagining a tsunami of those proportions, was this reviewed after Indonesia (etc) 2004? It just seems a shame – this could have been a showcase for nuclear power at its best.


Question on the Fukushima #2 site, apologies if I’ve missed the obvious answer. In the march 14th statement
( ) the reactors #2&4 at the second site were said to have increasing containment pressure and a failure of “Core coolabilit-1 (ECCS/RHR)”, containment venting was flagged as “to be decided”. Subsequent reports say “No Info” for the pressure increase, the previously reported failure has vanished as a reporting category and the “environmental affect” is now given as 8.99uS/h and colour coded as a high category.

Has there been any other reporting of the problems that were developing but seem to have disappeared as the radiation increases?


“Japan’s nuclear crisis intensified dramatically on Wednesday after the authorities announced that a second reactor unit at the stricken Fukushima Daiichi plant in northeastern Japan may have ruptured and appeared to be releasing radioactive steam. The break, at the No. 3 reactor unit, worsened the already perilous conditions at the plant, a day after officials said the containment vessel in the No. 2 reactor had also cracked. Such is the growing international alarm about the nuclear crisis that France announced it was urging its citizens living in Tokyo to head to safer areas or to leave the country — apparently the most urgent instruction offered by foreign countries that so far had largely limited their advisories to simply avoid non-essential travel.”

“Tests Wednesday revealed traces of radiation in tap water in Fukushima city, located 80 kilometers (50 miles) from the Daiichi nuclear plant, the local government said. The Fukushima Prefecture’s nuclear department said amounts of radioactive cesium and iodine that are not harmful to the human body were found in water samples taken at 8 a.m. Wednesday (7 p.m. ET Tuesday). Government officials said the traces found are connected with the nuclear plant. A measurement of the tap water supply taken later in the day found no traces of iodine or cesium.”


Russia offered Japan a team of nuclear experts who are Chernobyl-experts, but Japan rejected. They probably don’t want to give too much insights in how bad the situation is. I think if something is developing like this, one should put the cards on the table. It’s about time. But then there is this old tradition in Japan where people have to save one’s face. It’s tragic…


Sophia: Sorry, but that is an ignorant statement. While admittedly the transparency of some statements has not been perfect, there is nothing going on here about saving face. The problem is that people love to be scared and the mass media makes money from scaring them. You can’t scare people in the USA nd Europe with stories of an earthquake in Japan, and unfortunately the tsunami threat, as small as it really was, was a one-time event and is over. What’s left but the bogeyman of invisible radiation?

The people hosting and constributing to this site have done a remarkable job putting together a reasoned and responsible explanation of what has happened and what is likely to happen. You don’t have to believe it, but assigning blame to a people that are doing their best in the face of a truly horrible series of events is just wrong. And ignorant, but I mentioned ignorant before.


It could be that the multiple failures now evident at all six of the Fukushima reactors within a few days of one another have one common initiator. The tsunami is the obvious candidate. Not so much the flooding, (the reactor complex appears to have come through the inundation relatively unscathed) but what happened after the initial rush of water, …when the water receded to far below its normal level. Tsunami water levels are alternately excessively high and, perhaps more damaging to the reactors, excessively low. It could be that all the secondary cooling water intakes were left high and dry for some minutes. This would have played havoc with the heat exchangers and other plumbing, setting the scene for the subsequent primary cooling circuit and spent fuel pool problems. The loss of circulation may have tripped the back-up system which would in turn experience problems due to the absence of coolant (seawater).
A few minutes with no water before the next wave thundered in may have set off the unfortunate and tragic chain of events that we are witnessing. The problems reported at the Onagawa nuclear complex may indicate that it also experienced temporary secondary coolant (seawater) loss.
My thoughts and prayers are with the brave workers who are currently risking their lives to minimize the damage.


I agree with moonkoon and Peter to a degree: At this stage it’s less about withholding info to “save face” and more about doing the best they can with what they have (and saving everyone’s ass).

If you’ve ever been in a crisis situation, you’ll notice you tend to act and behave differently than if you’re calm and leisurely going over your options logically tick by tick. Have you ever said to yourself, “I should have—” or “Why didn’t I—“?

Much like martial arts, which tries to instill defense so it becomes instinctive and you don’t have to think about what to do; I don’t think the plant workers have been trained to the degree that they can just automatically do the perfect thing for every situation automatically; they have to react, give and take orders and go with whatever information they have at the time.

Unlike what was said by “its [sic] aboutSCALE.” It’s more about the timing and unknown.

All I know, the Japanese workers and gov’t are STILL doing better than FEMA did with Katrina and Rita. Thank goodness there weren’t any reactors in New Orleans! ;-)



what do you mean with ‘here’? are you japanese?
i was talking about a cultural fact, where japanese people just hardly involve people from outside in their business and get almost kind of embarrassed of stuff you cannot really blame them for. for example: there was staff at the airport saying: “excuse me for the tsunami..” and stuff like that to foreigners flying home.

that was what i was talking about. i cannot see where this is ignorant. i’m sorry. to me it seems more ignorant to NOT see those slight differences in culture, cause those – for sure – affect a lot. how people deal with stuff in general.

before you stigmatise someone with a word like ‘ignorance’, think about your own a bit. i never with one word doubted that people are trying to do their best. i just was saying, that they should just accept all the help they can get and forget about traditions in that case.


The Director of the Finnish Radiation and Nuclear Safety Authority, Mr. Jukka Laaksonen, has sharply criticized Japan for poor handling of the accident.

According to him, the Japanese learned nothing from 2004 Indian Ocean tsunami, their hierarchical work culture is hampering their efforts etc.

One of his Group Leaders, Mr.Keijo Valtonen, has given a rather different assessment of the Japanese efforts: they are doing what they can and have still things under control.

The French are losing their patience vis-a-vis the Japanese:

But are the critics right? Well, Wikileaks tells this story:



Sorry , but I find your statement to be ignorant as well as Peter – considering it was announced in the news that the team of Russian nuclear experts have arrived to Japan already. Besides the fact that Russia had sent the largest rescue team there as well.



The proof that to the lay person this is truly is about the scale of a potential nuclear disaster is evident in the media and even in this blog.

What is everyone’s real worry here? It is that an out of control reactor “melts” down in a manner that breaches these “unbreachable” containments and spews radiation into the atmosphere/contaminates the ground water table and so forth. A release of radiation is likely going to cause hysteria in a city of 9 million people 170 miles to the south (though to the credit of the Japanese people, their ability to stay relatively calm in these situation is admirable).

As to world media’s hype… It does not matter how many hacks they put on who are ridiculously ignorant and an obvious hype, its entertainment. But no one would watch or care if there wasn’t a certain truth behind it all. That truth is that in our gut we know “experts” always have there say, but in the end fate plays its hand. IF one or two of these plants go seriously wrong…the disaster will be on a scale that we will all then say should have never been allowed to happen by our own hand (technology).

The real problem is not nuclear energy…its the irresponsible use of nuclear energy.

Common sense tells most of us that you don’t build a power plant that uses technology that can lead to massive destruction and locate it in an earthquake fault zone close to population centers But social leaders, politicians, experts and scientists all convince themselves its doable and go right on ahead and do it.

Then when the plan goes south, and the outcome is uncontrolled and the possibility of a devastating tragedy looms on such a large scale…they tap dance for us about how it should not happen, how we can learn from this and so on..

Here is a thought…go find a mountain, drill a shaft a mile (or something reasonable) into it, carve out a home for a nuclear plant, create the infrastructure (coolant storage, etc) and set it up so that if it goes south you collapse the shaft and the news media reports, “power company writes off 2 billion dollar nuclear plant, no injuries reported, no radiation leaked, no threat to anyone”.


Um, to “Its[sic]aboutSCALE” (wonder if that’s your first or last name, lol), I’m not sure what the disagreement is.

My only point was that even if it’s low-level (“small scale” in my definition, not necessarily yours) nuclear radiation “leaking”, people still get freaked out even if it’s not harmful because of the timing (sudden and unexpected), ignorance, lack of education and fear–fear of the *unknown.* Since they don’t know/understand what’s really going on and what the consequences are, it ups the fear factor. In contrast, the layfolk know that someone dies from cancer every minute and that millions die in car accidents per year; but they understand and know more about them and have a certain level of control. We knew thousands of people died in Katrina and Rita (huge scale), but knew it was confined to the South. That’s all. No argument, only clarification.

I don’t disagree with your other points.


This kind of thing demands an ‘answer factory’. Regardless of opinion, the systematic distribution of answers and catalisation of questions is non existant. This requires funding and round the clock maintenance. One single link that clearly shows the way to any level of information from actual minute to minute situation update to subject related panic and soap blogs. Does anyone know who can organize anything like this?


The major problem is that cooling the nuclear products requires functioning of the designed cooling system, especially for the waste ponds.The jerry-rigged cooling system can never be as effective. The window for fixing the problem closes as radiation makes it less safe for workers to be in site. Luckily, Japan has a Kamikaze culture and they will try to fix it. Time will tell if this turns into the worst nuclear disaster in human history. An ABC interview with a European nuclear consultant lat night said the handling of this accident was a reflection of the nuclear safety culture – ie the amount of money that can be spent to manage uncommon risks. Nuclear energy can only be made more expensive if it is to be made safer. Go carbon tax.


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