Preliminary lessons from Fukushima for future nuclear power plants

No strong conclusions can yet be drawn on the Fukushima Nuclear Crisis, because so much detail and hard data remains unclear or unavailable. Indeed, it will probably take years to piece the whole of this story together (as has now been done for accidents like TMI and Chernobyl [read this and this from Prof. Bernard Cohen for an absolutely terrific overview]). Still, it will definitely be worth doing this post-event diagnostic, because of the valuable lessons it can teach us. In this spirit, below an associate of mine from the Science Council for Global Initiatives discusses what lessons we’ve learned so far. This is obviously a huge and evolving topic that I look forward to revisiting many times in the coming months…

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Guest Post by Dr. William HannumBill worked for more than 40 years in nuclear power development, stretching from design and analysis of the Shippingport reactor to the Integral Fast Reactor. He earned his BA in physics at Princeton and his MS and PhD in nuclear physics at Yale. He has held key management positions with the U. S. Department of Energy (DOE), in reactor physics , reactor safety, and as Deputy Manager of the Idaho Operations Office.

He served as Deputy Director General of the OECD Nuclear Energy Agency, Paris, France; Chairman of the TVA Nuclear Safety Review Boards, and Director of the West Valley (high level nuclear waste processing and D&D) Demonstration Project. Dr. Hannum is a fellow of the American Nuclear Society, and has served as a consultant to the National Academy of Engineering on nuclear proliferation issues. He wrote a popular article for Scientific American on smarter use of nuclear waste, which you can download as a PDF here.

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Background

On 11 March 2011, a massive earthquake hit Japan.  The six reactors at Fukushima-Dai-ichi suffered ground accelerations somewhat in excess of design specification.  It appears that all of the critical plant equipment survived the earthquake without serious damage, and safety systems performed as designed.  The following tsunami, however, carried the fuel tanks for the emergency diesels out to sea, and compromised the battery backup systems.  All off-site power was lost, and power sufficient operate the pumps that provide cooling of the reactors and the used-fuel pools remained unavailable for over a week.  Heroic efforts by the TEPCo operators limited the radiological release.  A massive recovery operation will begin as soon as they succeed in restoring the shutdown cooling systems.

It is important to put the consequences of this event in context.  This was not a disaster (the earthquake and tsunami were disasters).  This was not an accident; the plant experienced a natural event (“Act of God” in insurance parlance) far beyond what it was designed for.  Based on the evidence available today, it can be stated with confidence that no one will have suffered any identifiable radiation-related heath effects from this event.  A few of the operators may have received a high enough dose of radiation to have a slight statistical increase in their long term risk of developing cancer, but I would place the number at no more than 10 to 50.  None of the reports suggest that any person will have received a dose approaching one Sievert, which would imply immediate health effects.

Even ignoring the possibility of hormetic effects, this is approaching the trivial when compared with the impacts of the earthquake and tsunami, where deaths will likely come to well over 20,000.  Health impacts from industrial contamination, refinery fires, lack of sanitation, etc., etc. may reasonably be supposed to be in the millions.  Even the “psychological” impacts of the Fukushima problems must be seen to pale in contrast to those from the earthquake and tsunami.

The radiological impact on workers is also small relative to the non-radiological injuries suffered by them.  One TEPCO crane operator died from injuries sustained during the earthquake. Two TEPCO workers who had been in the turbine building of Unit 4, are missing.  At least eleven TEPCO workers were take to hospital because of earthquake-related physical injuries.

TEPCO has suffered a major loss of capital equipment, the value of which is non-trivial even in the context of the earthquake and tsunami devastation.  They also face a substantial cost for cleanup of the contamination which has been released from the plants. These are financial costs, not human health and well being matters.

The Sequence of Events

Following the tsunami, the operators had no power for the pumps that circulate the primary coolant to the heat exchangers.  The only way to remove the decay heat was to boil the water in the core.  After the normal feed water supplies were exhausted, they activated the system to supply sea water to the core, knowing this would render the plant unfit to return to operation.  In this way, the reactors were maintained in a relatively stable condition, allowing the water to boil, and releasing the resulting steam to the containment building. Since this is a Boiling Water Reactor (BWR), it is good at boiling water.  Operating with the water level 1.7 to 2 meters below the top of the core, they  mimicked power operation; the core normally operates at power with the water level well below the top of the core, the top part being cooled by steam.   Cold water in, steam out, is a crude but effective means of cooling.

Before using sea water, according to reports, water levels are thought to have dropped far enough to allow the fuel to overheat, damaging some of the fuel cladding.  When overheated, the cladding (Zirconium) reacts, claiming oxygen from the water.  Water, less oxygen, is hydrogen.  When vented to the containment and then to the outer building, the hydrogen built up, and eventually exploded, destroying the enclosing building.  With compromised fuel, the steam being vented contains radioactive fission products.  The design of BWRs is such that this venting goes through a water bath (in the Torus), that filters out all but the most volatile fission products.

With time, the heat generated in used fuel (both in the core and in the fuel pool) decreases.  From an initial power of about 2% of full power an hour after shutdown (when the coolant pumps lost power) to about 0.2% a week later, the amount of steam venting decreases, and releases can be controlled and planned for favorable weather conditions.

A second concern arose because of the inability to provide cooling for the used-fuel pool in Unit 4, and later Unit 3.  The Unit 4 pool was of concern because, for maintenance, the entire core had been off-loaded into the pool in November (it is believed that two older core loadings were also in this pool, awaiting transfer to the central storage pool).  With only a few months cooling, the residual heat is sufficient to raise the temperature of the water in the pool to boiling within several days or weeks.  There is also some suggestion that the earthquake may have sloshed some water out of the pool.  In any case, the fuel pools for Units 3 and 4 eventually were thought to be losing enough water such that the fuel would no longer be adequately cooled.  Since the fuel pools are outside the primary containment, leakage from these pools can spread contamination more readily than that from the reactor core.  High-power water hoses have been used to maintain water in the fuel pools.

While many areas within the plant complex itself, and localized areas as far away as 20 Km may require cleanup of the contamination released from the reactors and from the fuel pools, there is no indication that there are any areas that will require long term isolation or exclusion.

Lessons Learned

It is not the purpose of this paper to anticipate the lessons to be learned from this event, but a few items may be noted.  One lesson will dominate all others:

Prolonged lack of electrical power must be precluded.

While the designers believed their design included sufficient redundancies (diesels, batteries, redundant connections to the electrical grid), the simultaneous extended loss of all sources of power left the operators dependant on creative responses.  This lesson is applicable both to the reactor and to fuel pools.

All nuclear installations will probably be required to do a complete review of the security of their access to electrical power.  It may be noted that this lesson is applicable to many more activities than just nuclear power.  Extended loss of electrical power in any major metropolitan area would generate a monstrous crisis.  The loss of power was irrelevant to other activities in the region near the Fukushima plant because they were destroyed by the tsunami.

Other lessons that will be learned that may be expected to impact existing plants include:

Better means of control of hydrogen buildup in the case of fuel damage may be required.

In addition, detailed examinations of the Fukushimi plants will provide evidence of the margins available in seismic protection.  Detailed reconstruction of the event will give very helpful insights into the manner that fission product can release from damaged fuel, and their transport.

Applicability of Fukushima Information to MOX-fueled Reactors:

The core of Unit 3 was fueled with plutonium recycled from earlier used reactor fuel.  Preliminary information suggests that the release of hazardous radioactive material, for this type of event, is not significantly different than that non-recycle fuel.  More detailed examinations after the damaged cores are recovered, and models developed to reconstruct the events, will be necessary to verify and quantify this conclusion.

Applicability of Fukushima Information to Gen-III Reactors:

In the period since the Fukushima plants were designed, advanced designs for BWRs (and other reactor types) have been developed to further enhance passive safety (systems feedback characteristics that compensate for abnormal events, without reliance on operator actions or on engineered safety systems), simplify designs, and reduce costs.  The results of these design efforts (referred to as Gen-III) are the ones now under construction in Japan, China and elsewhere, and proposed for construction in the U.S.

One of the most evident features of the Gen-III systems is that they are equipped with large gravity-feed water reservoirs that would flood the core in case of major disruption.  This will buy additional time in the event of a Fukushima type situation, but the plants will ultimately rely of restoration of power at some point in time.

The applicability of the other lessons (hydrogen control, fuel pool) will need to be evaluated, but there are no immediately evident lessons beyond these that will affect these designs in a major way.

Applicability of Fukushima Information to Recycling Reactors:

As noted above, Unit-III was fueled with recycled plutonium, and there are no preliminary indications that this had any bearing on the performance of this plant during this event.

Advanced recycling, where essentially all of the recyclable material is recovered and used (as opposed to recovery and recycle of plutonium) presents a different picture.  Full recycling is effective only with a fast reactor.  A metal fuel, clad in stainless steel, allows a design of a sodium-cooled fast reactor with astonishing passive safety characteristics.  Because the sodium operates far from its boiling point in an essentially unpressurized system, catastrophic events caused by leakage or pipe failures cannot occur.  The metal fuel gives the system very favorable feedback characteristics, so that even the most extreme disruptions are passively accommodated.  A complete loss of cooling, such as at Fukushima, leads to only a modest temperature rise.  Even if the control system were rendered inoperable, and the system lost cooling but remained at full power (this is a far more serious scenario than Fukushima, where the automatic shutdown system operated as designed) the system would self-stabilize at low power, and be cooled by natural convection to the atmosphere.  Should the metal fuel fail for any reason, internal fission product gases would cause the fuel to foam and disperse, providing the most powerful of all shutdown mechanisms.

The only situation that could generate energy to disperse material from the reactor is the possibility of s sodium-water reaction.  By using an intermediate sodium system (reactor sodium passes its energy to a non-radioactive sodium system, which then passes its energy to water to generate steam to turn the electrical generator), the possibility of a sodium-water reaction spreading radioactive materials is precluded.

These reactors must accommodate seismic challenges, just as any other reactor type.  While there are many such design features in common with other reactor designs, the problem is simpler for the fast reactor because of the low pressure, and the fact that this type of reactor does not need elaborate water injection systems.

In light of the Fukushima event, one must consider the potential consequences of a massive tsunami accompanying a major challenge to the reactor.  Since it may be difficult to ensure that the sodium systems remain intact under the worst imaginable circumstances, it may be prudent to conclude that a tsunami-prone location may not be the best place to build a sodium facility (whether a nuclear power plant or something else).

Conclusions:

The major lesson to be learned is that for any water-cooled reactor there must be an absolutely secure supply of power sufficient to operate cooling pumps.  Many other lessons are likely to be learned.  At this early point, it appears that design criteria for fuel storage pools may need to be revised, and hydrogen control assessed.

Given the severity of the challenge faced by the operators at Fukushima, and their ability to manage the situation in such a way as to preclude any significant radiation related health consequences for workers or the public, this event should be a reassurance that properly designed and regulated nuclear power does not pose a catastrophic risk to the public—that, overall, nuclear power remains a safe and clean energy sources.

Given the financial impact this event will have on the utility (loss of four major power plants, massive cleanup responsibilities), it will be worthwhile for the designers, constructors, operators, and licensing authorities to support a thorough analysis of what actually transpired during this event.

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164 Comments

  1. Something worth considering when someone (inevitably) says to you: “Ahhh, but they were lucky at Fukushima. It could have been much worse”:

    http://www.phyast.pitt.edu/~blc/book/chapter6.html

    The Worst Possible Accident

    One subject we have not discussed here is the “worst possible nuclear accident,” because there is no such thing. In any field of endeavor, it is easy to concoct a possible accident scenario that is worse than anything that has been previously proposed, although it will be of lower probability. One can imagine a gasoline spill causing a fire that would wipe out a whole city, killing most of its inhabitants. It might require a lot of improbable circumstances combining together, like water lines being frozen to prevent effective fire fighting, a traffic jam aggravated by street construction or traffic accidents limiting access to fire fighters, some substandard gas lines which the heat from the fire caused to leak, a high wind frequently shifting to spread the fire in all directions, a strong atmospheric temperature inversion after the whole city has become engulfed in flame to keep the smoke close to the ground, a lot of bridges and tunnels closed for various reasons, eliminating escape routes, some errors in advising the public, and so forth. Each of these situations is improbable, so a combination of many of them occurring in sequence is highly improbable, but it is certainly not impossible.

    If anyone thinks that is the worst possible consequence of a gasoline spill, consider the possibility of the fire being spread by glowing embers to other cities which were left without protection because their firefighters were off assisting the first city; or of a disease epidemic spawned by unsanitary conditions left by the conflagration spreading over the country; or of communications foul-ups and misunderstandings caused by the fire leading to an exchange of nuclear weapon strikes. There is virtually no limit to the damage that is possible from a gasoline spill. But as the damage envisioned increases, the number of improbable circumstances required increases, so the probability for the eventuality becomes smaller and smaller. There is no such thing as the “worst possible accident,” and any consideration of what terrible accidents are possible without simultaneously considering their low probability is a ridiculous exercise that can lead to completely deceptive conclusions.

    The same reasoning applies to nuclear reactor accidents. Situations causing any number of deaths are possible, but the greater the consequences, the lower is the probability. The worst accident the RSS considered would cause about 50,000 deaths, with a probability of one occurrence in a billion years of reactor operation. A person’s risk of being a victim of such an accident is 20,000 times less than the risk of being killed by lightning, and 1,000 times less than the risk of death from an airplane crashing into his or her house.

    But this once-in-a-billion-year accident is practically the only nuclear reactor accident ever discussed in the media. When it is discussed, its probability is hardly ever mentioned, and many people, including Helen Caldicott, who wrote a book on the subject, imply that it’s the consequence of an average meltdown rather than of 1 out of 100,000 meltdowns. I have frequently been told that the probability doesn’t matter — the very fact that such an accident is possible makes nuclear power unacceptable. According to that way of thinking, we have shown that the use of gasoline is not acceptable, and almost any human activity can similarly be shown to be unacceptable. If probability didn’t matter, we would all die tomorrow from any one of thousands of dangers we live with constantly.

  2. @Barry Brook
    This is the best link I have seen posted during this entire event. It really takes level headed and calm reasoning to get the point, presented by this author, across to most people.

  3. “Given the severity of the challenge faced by the operators at Fukushima, and their ability to manage the situation in such a way as to preclude any significant radiation related health consequences for workers or the public”

    That quote states as a given, things that have already proved untrue!

    “Thursday, March 24, 7 p.m. ET, Tokyo

    Tokyo Electric Power Company (TEPCO) reported that three people, who were working in the turbine building of unit 3, suffered radiation exposure between 170 millisieverts and 180 millisieverts. Two suffered beta ray skin burns and were immediately transferred to a hospital. The dose limit for emergency work is now set at 250 millisieverts (amended from 100 millisieverts).

    These are the first serious radiation-exposed injuries during this crisis. Feel for them.”

    From:

    http://www.thebulletin.org/web-edition/columnists/tatsujiro-suzuki/daily-update-japan

  4. “Tokyo Electric Power Company (TEPCO) reported that three people, who were working in the turbine building of unit 3, suffered radiation exposure between 170 millisieverts and 180 millisieverts.”

    Hmm. When did this happen? Only in the last couple of days, or in the early stages of the incident?

    What radionuclides could be present that would be responsible for beta burns and such relatively large doses?

    I’m interested in finding out as much as possible about exactly what the circumstances were whereby this happened.

    At this time, I would have to make an educated guess of I-131 or Xe-133, although if it was earlier on it might have been the much higher activities that were present from Te-132 or I-132.

  5. As a sceptic/unsure/undecided, I have a hard time with such statements, “According to that way of thinking, we have shown that the use of gasoline is not acceptable, and almost any human activity can similarly be shown to be unacceptable. If probability didn’t matter, we would all die tomorrow from any one of thousands of dangers we live with constantly.”

    It’s a illogic argument to counteract a valid point (the anti-nuke crowd can make valid points too).

  6. Luke Weston,

    The report I heard on the radio this morning (NPR “Morning Edition”) stated that the two workers were in a partly-flooded basement installing electrical cables. For a time, they were standing in water, which turned out to be very radioactive. The burns were to their legs.

    The date and time of the exposure weren’t specified, the weren’t isotopes identified. I don’t recall the reactor being named, either.

  7. Even being the person who, many days ago now, faulted many on this site for talking as if what had happened and what was happening was the worst possible that could have happened (and thereby being “Panglossian” I think I said), I really really appreciated and liked that piece quoted above by Professor Brook from that U. of Pittsburgh guy.

    Very clarifying to think of it as being … while things *can* always get worse, the *worse* the possible the less the probability of it happening.

    However, two points do still spring to mind:

    First, while that “probability” dynamic is no-doubt true, it also seems to me true that sometimes, some still very very serious worse things can happen after some only mildly improbable things have occurred. Let’s say … some technician at the Fuku plant has forgotten to close valve X or Y, and *then* what happened happened, leading to something much much worse than we have seen.

    Not *catastrophically* worse I wouldn’t suspect, obeying the U. of Pitt guy’s logic, but, still, pretty damn much worse.

    Or, to use another example, some “improbable” but still not insanely unlikely weather thing had happened at just the wrong time. Or maybe, given their appalling apparent frequency in history, that tsunami had been much much higher and just smashed the whole plant to bits….

    My second observation is that I think the U. of Pitt guy talks about bad consequences a little too solely based on deaths alone. I mean … one could envision a situation where an accident happens, it is prepared for and seen, a huge evacuation takes place entirely successfully and nobody is killed, but … nobody can live in Tokyo for another 1000 years or however long.

    I think most people would consider something like having big swathes of land being uninhabitable for a long time as being a very very serious thing so that merely confining one to talking about nuke power risks being human deaths is I think a bit narrow.

    Otherwise though just delighted with that U. of Pitt article and link, so thanks Professor Brook. Nice spotting on your part. That Pitt guy knows how to talk nice and clearly for sure.

  8. I picked up a used copy of Cohen’s book online for a few bucks. It was easier to study, for an old geezer like me, than staring at a screen.

    Bruce Gellerman of Public Radio International has interviewed Robert Alvarez of Alvarez et.al. i.e. the guy who led the study that the NAS NRC 2006 tiook as its starting point when it considered what happens if a spent fuel pool goes dry. http://www.loe.org/shows/segments.html?programID=11-P13-00011&segmentID=2

    I re read the NAS NRC 2006 study with a view to getting a better handle on what it can tell us now as to what the risk at Fukushima actually was at the height of the crisis. What I would like to see as soon as possible is an accurate assessment of how many other factors would have had to be in place even at that time to cause the worst case radiation release.

    Gellerman has used his show in the past as a mouthpiece for anti nuke propaganda it seems, anyway here is a comment I sent to him regarding this Alvarez interview.

    “People should read the the report the NAS NRC published that Alvarez says “weighed in” on this issue of what happens if a pool goes dry. Living on Earth’s (LOE’s) Gellerman dug up a certain Gordon Thompson for his LOE previous report on these pools (“Waste Not Want Not”), who described US reactor pools as “radiological weapons awaiting activation by an enemy”, and Gellerman actually reported that the NAS report (I refer to it as NAS NRC 2006) “agreed” with that analysis. They didn’t. I bring this up to caution anyone hearing this LOE report or reading this transcript that any careful observer would say LOE and Gellerman have an anti nuclear power bias that is this obvious.

    The NAS NRC 2006 took Alvarez et. al. scenarios and examined them. They also noted that the US NRC (the Nuclear Regulatory Commission, as opposed to the National Research Council the NRC in NAS NRC 2006 stands for) itself had done a study which drew “some” of the same conclusions Alvarez did, i.e. if a zirc fire broke out it “would probably” lead to a release of fission products “comparable” to what “molten fuel in a reactor core” would. After describing that the Alvarez study had been extensively reviewed and commented upon, with people disputing Alvarez et. al. assessment of what the likelihood of a zirc fire was and how great the offsite consequences could be the NAS NRC 2006 then wrote: “The committee provides a discussion of the Alvarez et al. (2003a) analysts in its classified report. The committee judges that some of their release estimates should not be dismissed.”

    Which is a very long way from Gellerman’s previous report that the NAS “agreed” with Thompson’s wild statement that these pools are “radiological weapons awaiting activation by an enemy”.

    What is the actual size of this threat? How many layers of defense were still left at Fukushima? Given that Unit #4’s pool was packed at low density, and its exact arrangement of rods and their age, was the possibility of a fire there at all? I.e. The NAS NRC 2006 recommended that rods be rearranged in US pools to lower the odds of a zirc fire breaking out.

    LOE would have us believe its just let the water drain out and hell is upon us. This is reporting?

    The NAS NRC 2006 noted that the computer simulation results able to be examined by them in 2006 had deficiencies which included “the computer models” used “had not been validated for this application”, they were described as based on “simplistic” assumptions and the NAS NRC 2006 noted “The thermal analysis experts on the committee judge that these simplistic assumptions could produce results that are more severe (i.e., overconservative) than would be the case had more realistic assumptions been used” which which made it “not possible to predict the precise magnitude” of what could happen.

    Ten years of the most aggressive solar subsidy program in the world got Germany about one reactor’s worth of electricity for its grid and the cost exceeded $40 billion US. LOE says it is an “independent environmental voice”. I’ve been a climate activist for more than 20 years, and I remember when the NGOs didn’t make climate their main issue. I remember when the Sierra Club advocated nuclear power. The position the NGO environmentalist community takes on nuclear evolved before their position on climate (examine the dates on the Friends of the Earth climate and nuclear policy statements) and they have yet to reevaluate their position on nuclear by examining the facts, as opposed to assumptions created by telling each other that the facts are as LOE would have us believe.

    The issue is serious and the hour is getting late. What we need is a sober look at what happened at Fukushima and what the implications are for us in the US.

  9. One thing I haven’t seen talked about is who is going to pay for the cleanup of these reactors. Is TEPCO going to go bankrupt doing so? They have already suspended their dividend and profit projections (go to their site). This is not even considering liability claims. Does Japan have laws limiting liability as have been passed elsewhere?

  10. @William Fairholm:
    Two separate questions there:
    The expense of the reactor clean-up.
    The expense of the dislocation to the surrounding community, the possibility that for a short period come people close in to the reactor might not be able to move back and so on.
    I doubt that TEPCO will be held fully liable for those any more than the oil and gas companies will be held responsible for the actual explosions and release of carcinogens from their plants, with unknown in total but surely in many cases lethal consequences, or oil and gas companies shares would be plummeting.

  11. I heard a Bloomberg Surveillance podcast interviewing an expert on Japanese insurance practice – the idea was to get a handle on whether widespread insurance company bankruptcies could be expected. Japanese insurers generally do not cover what we call “acts of God”, so the expert suggested no problemo there. Another assessment of Japan’s overall ability to withstand the financial shock here, focussed on will it start selling its US treasuries, concluded that Japan has an internal savings rate so high it has no problems raising loans from its own people’s savings at any conceivable scale it will need to deal with this. TEPCO on the other hand may find its gone bankrupt, but this kind of thing just means someone else in Japan has to come up with the cash. What TEPCO does, i.e. provide electricity to part of Japan, will continue.

  12. William Fairholm wrote:

    “Does Japan have laws limiting liability as have been passed elsewhere?”

    I don’t know the answer to that, and I hate taking up bandwidth by posting again so soon after I just posted something else, but this does jog a question I have.

    I understand that in the U.S. it is impossible to get insurance for nuke plants, and thus legal immunity from at least some suits is necessary for any to get built. (And I’d at least bet a little that the same is true for Japan as well given the international nature of the insurance market.)

    Due to same then I have heard the anti-nuke argument that this simply shows that the risks of nuke power are too much even for the sophisticated. (That is, the big insurance companies who can afford to investigate risks to the max and who then have presumably done so and concluded that they won’t extend coverage.)

    And this seems to me to at least be an argument with *some* sophistication behind it: I.e., it acknowledges that there’s risks with everything, and just says “hey,” the *best* way to evaluate the acceptability of same is in the market of free ideas which is essentially what the insurance market is. So that if *that* market says the risk is just too much, well why, unlike everything else essentially, should we then ignore that judgment?”

    Would be interested in hearing responses to this line of argument. Including, for instance, what people think of the idea of saying that sure, we ought to allow Generation II or III or X reactors absolutely freely, but only if they can get insurance coverage?

    That is, why isn’t that a good/valid argument if these advanced generation plants are supposedly so much better?

  13. American, on 25 March 2011 at 3:30 AM said:

    “one could envision a situation where an accident happens, it is prepared for and seen, a huge evacuation takes place entirely successfully and nobody is killed, but … nobody can live in Tokyo for another 1000 years or however long.”

    I suspect it is no coincidence that there are no reactors within 100 miles or more of Tokyo. See the map on page 3 here:

    http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300951089P.pdf

    I agree with you that the risk of rendering land uninhabitable is probably the greatest risk to society and that is exacerbated by the “zero tolerance” view of radiation promulgated by the anti-nuclear crowd. It is conceivable, for example, that land could be needlessly evacuated on a more or less permanent basis after an incident for no scientifically valid reason.

    “Or, to use another example, some “improbable” but still not insanely unlikely weather thing had happened at just the wrong time.”

    I thought that is more or less what happened at Fukushima :-). (substitute weather for Act of God/Nature).

  14. If a building collapses due to the earthquake and/or tsunami, and kills people plus does damage to other property, who are you going to sue or send a bill? The building owner? God perhaps? Mother Nature?

    The latter two are, uhm, practically difficult, while the first option seems weird. But when its a nuclear powerplant in the same eartquake event, suddenly the nuclear plant owner is fully liable? Who is going to sue the collapsed building owner for not building his structure to stand 9 moment magnitude earthquakes?

    That’s called nuclear exceptionalism. And its speculating anyway. TEPCO would likely be held fully liable for the expense of decommissioning, and rightly so IMHO, but we have yet to see the extent of ground contamination in the surrounding area. If its limited, TEPCO might pay up to help make amends. Again all speculation because we don’t know enough about it right now… lets not get ahead of the situation too much shall we!

  15. “re robguima, on 25 March 2011 at 2:31 AM said:
    ….It’s a illogic argument to counteract a valid point (the anti-nuke crowd can make valid points too).”

    it’s not clear to me what “valid point” you think the anti-nuke crowd is making. As best I can determine their “point” is that certain deaths are more preferable than others, nuclear being the least preferable.

    A one in a billion reactor-year event, assuming 1000 reactors (only 400 some in existence now), is a once in a million year event. It is highly unlikely the human species will survive a million years without some extinction level event. The loss of 50,000 people for any reason, from any single event, in the next million years is trivial. In fact, we suffer multiple 50,000 death events in the course of any normal century now, and very likely any run of the mill decade.

    It should be an objective game of statistics, right down to the worst possible scenario. Especially in the context of current events where AGW is claimed by many to be a certain extinction level event for our species. It’s not a matter of trying to decide if some economic benefit from nuclear is worth x risk over x time.

    [deleted personal opinion presented as fact. Please re-submit with references/links.]

  16. Any large chemical or industrial installation, not just nuclear, is not held fully accountable or insured for all possible losses.
    They screwed a fair amount out of BP, as it was a ‘foreign’ company, with substantial assets, but the practical limit for the GOM oil release had it been a smaller, and American, company would have been far lower.
    How much was paid for Bhopal?
    Greenpeace et al’s argument that the nuclear industry is unique in not having to insure for all conceivable or inconceivable events is entirely specious.

  17. American, on 25 March 2011 at 3:57 AM said:
    “I understand that in the U.S. it is impossible to get insurance for nuke plants”
    False. All US nuclear plants take $300+million of private liability insurance,

    http://www.nuclearinsurance.com/

    UK equiv: http://www.nuclear-risk.com/

    There may be some confusion with a rule that forbids insurance companies from offering separate protection from nuclear incidents to eg. homeowners. As I understand it, this is to stop insurance scams, since all liabilities arising from nuclear plant operations are paid on a no-fault basis (no need to prove negligence etc, only to prove loss).

  18. “All off-site power was lost, and power sufficient operate the pumps that provide cooling of the reactors and the used-fuel pools remained unavailable for over a week.”

    When the subject of earthquakes, tsunamis, and siting of nuclear plants inevitably comes up, instead of getting sidetracked, let’s gently remind folks that a constructive examination of this incident starts with “loss of off-site power”.

  19. One thing that could be done to assist the used-fuel storage issue is to make the use of dry cask storage a routine part of every nuclear power plant. No additional license amendments, discussion or justification required.

  20. NR99, there are plenty of scientists who accept the overwhelming preponderance of evidence for AGW, and many of them also support rapid development of nuclear solutions. “Belief” in AGW one way or the other is also correlated along political lines, but scientific evidence apparently doesn’t affect the thinking of either side.

    If all the carbon dioxide was removed from the atmosphere, the Earth would become a frozen snowball. CO2 has a profound effect on climate.

    The Discovery of Global Warming

    http://www.aip.org/history/climate

  21. American, on 25 March 2011 at 3:57 AM said:

    “I understand that in the U.S. it is impossible to get insurance for nuke plants”

    In addition each plant also has to carry an additonal $100 million for losses occuring at any plant where the losses exceed $300 million. So we there is an additional $10 billion in coverage.

  22. @David Lewis 25 Mar 3:38

    Regarding Reactor 4, I believe the following 3 atatements are accurate:

    1) Reactor 4’s 548 fuel assemblies were offloaded to the R4 SFP on Nov 30 2010 adding to the 783 already there.

    2) During the earthquake on Mar 11 2010, there was no fuel in the reactor. There was no cooling problems, no subsequent seawater injection to this reactor and no venting.

    3) On Mar 15 there was a large explosion in the building housing R4. Satellite photos show that the R4 building was not damaged by the previous R3 explosion. Photos indicate an internal explosion and damage to the roof and top sidewalls of R4 building.

    The question is why did building 4 exlpode?

    Explosions in R1 and R3 have been attributed to H2 vented along with steam from the R1 and R3 reactors.

    If there was a H2 explosion in building 4, where did the H2 come from? If it was from something other than H2, what was it?

  23. Leo, One thing I find interesting about the photos now available of damage to the buildings of reactors 1, 3 and 4 is that the “flimsier” roof of reactor building 1 may have helped save it from the more significant damage suffered by reactor building 3, Reactor building 4 is still a puzzle that wil have to wait for more detailed review, I think.

  24. @nkinnear I analyzed this possibility on the 10+days comment thread 24 Mar 10:10AM and 10:57 AM correction.

    Maybe both hot Zr oxidation by steam and radiolysis generated H2. In any event, the 3 facts above plus analysis strongly implicate R4 SFP.

    It seems to me that SFP’s need both cooling and H2 removal either from circulating water or the open space above them. Especially true after loss of power accidents

  25. NR99, on 25 March 2011 at 4:08 AM said:

    A one in a billion reactor-year event, assuming 1000 reactors (only 400 some in existence now), is a once in a million year event.

    That is one in a million per year. So after 50 yrs of operation, there would be a chance of one in 20 thousand of this happening during that period. I think for nuclear supplying a large part of our energy needs for the next century we would need at least 2000 of them, so the chance of this very bad reactor event happening over the next 100 yrs would be one in 2000. And of course many more smaller accidents. Starts to get into the realm of you want to think carefully and say even given this risk, the “fallout” of not using nuclear are much worse.

  26. seamus, on 25 March 2011 at 4:32 AM said:

    “All off-site power was lost, and power sufficient operate the pumps that provide cooling of the reactors and the used-fuel pools remained unavailable for over a week.”

    When the subject of earthquakes, tsunamis, and siting of nuclear plants inevitably comes up, instead of getting sidetracked, let’s gently remind folks that a constructive examination of this incident starts with “loss of off-site power”.

    —-

    Actually, it starts with a 40 year old outdated reactor originally designed for submarines that requires an elaborate external mechanical and cooling system controlled by 1960s era analog and mechanical control rooms, that lost off-site power.

  27. re William Fairholm, on 25 March 2011 at 5:38 AM said:

    The cost of 2000 reactors would be in the order of trillions of dollars. Somewhere in those trillions it would be reasonable to assume the *current risks* would be lowered even further. Your numbers are actually “worst case” assuming those 2600 reactors are built to today’s (and yesterday’s) standards.

    “Starts to get into the realm of you want to think carefully and say even given this risk, the “fallout” of not using nuclear are much worse.”

    My point exactly, although we can quibble over the numbers :-)

    And remember, even given your 1 in 2000 chance over the next 50 years, that is for a single 50,000 death event. Over the next 50 years, millions will perish from other natural events such as floods, Tsunamis and earthquakes. That is a statistical certainty that we never bother to discuss.

    A similar worst case AGW event over the next 50-200 years usually discusses fatalities in the billions, just to return to my original context :-).

  28. What about the chance of a megavolcano erupting over the next hundred years? It is more likely than 1 in a million. Yellowstone for example is statistically overdue. If you power the world with solar and have global dust due to the megavolcano, you are facing years of large reduced solar output, and your fossil and nuclear plants all closed or mothballed it means you can’t rapidly turn back to fossil and nuclear sources, at least not to cover most energy needs. That’s the last thing you need, as if reduced food output and increased lung cancer aren’t bad enough you are seriously increasing pressure for global war and chaos with insufficient energy supply across the entire world. How many would die, worst case, with little or no heat and electricity? A billion, easily. I’m quite sure most here have seen the movie Mad Max…

    This is the area you are going into when talking about 1 in a million year events.

  29. @Leo Hansen

    Sorry, haven’t been able to read every post here.
    When I used to do H2 generation calculations, we used to use a value of 0.45 molecules of H2 per 100 ev. Based on that figure, I estimated a H2 generation rate of about 1 liter/sec (STP) of H2 for 1 MW of gamma radiation. I have seen various estimates of the heat generation of SFP in the low single digit MW range, much of which would be gamma. Of course, without knowing the free air space above the pool, I have no idea how long it would take to reach a 4% H2 value, which is around the minimum explosive concentration.

  30. @Leo Hansen What I’d like to see is whatever state of the art computer simulation exists that has been validated to assess a spent fuel pool loss of coolant event in a BWR pool just like Unit 4 to analyse that particular group of rods you describe, assuming you are accurate. If this was done, it would put more reality into the debate about how close this Fukushima incident came to precipitating the worst case the NRC admitted had some possibility of happening. At this point the debate assumes the worst was possible, and if it wasn’t, the whole debate out there among the reasonable but until now not that interested in nuclear matters people who through the ballot box will decide what is done is going to make an ill informed decision.

  31. “seamus, on 25 March 2011 at 4:46 AM said:
    NR99, there are plenty of scientists who accept the overwhelming preponderance of evidence for AGW, and many of them also support rapid development of nuclear solutions”

    My assessment is that Barry Brook (one of those that believes in AGW but also advocates nuclear) is in the minority and the fact that he is a relative tiny minority is why this site is important and it’s reason for existence. I would suggest Barry is an iconoclast in his field; cedrtainly not “main stream”.

    I am trying hard to stay away from any discussion of what is a belief verse “fact” in a field where nothing is falsifiable by experiment, especially the “snowball hypothesis”. It would be an interesting experiment but I think the EPA would shut it down before it got started, assuming it could be done (which, of course, it cannot).

    Most cosmologists consider the big bang “a fact” but again, no experimental falsification is possible. What is “fact” and what is “belief” is not as cut and dried as it is often made out to be. Fortunately no one is trying to modify the world’s lifestyle and economies based on big bang theory.

  32. The major lesson to be learned is that for any water-cooled reactor there must be an absolutely secure supply of power sufficient to operate cooling pumps.

    This is not any new major lesson. Boiler operators have known for 200 years and reactor operators for 60 years that you must keep water in devices designed to generate steam. Even a housewife knows it is a screw up to let the pot run dry.
    It is shameful that Fukushima reactors survived very strong earthquake and tsunami(so don’t blame those forces) just to be lost due to broken link in natural safety defenses.
    Relying on external electric power from any source was that absolute unforgiving broken link.
    BWR are designed to boil water, hence it is natural to use steam generated by decay heat to power own water feed, condenser circulation and other emergency cooling purposes.
    A lot of engineers, I was one of them, were seriously concerned about the reliance on external electric power for emergency reactor cooling because of numerous things that can go wrong in electric system during natural disaster, such as, broken wires and cables, damaged switches, damaged relays and controls, short circuits in power circuits as well as in control circuits, etc. The event in Fukushima exceeded all of the concerns for electric reliability because the Murphy’s law (anything that can go wrong will go wrong) was sugar coated by flooding electric equipment with electrically conductive sea water.
    Just three weeks before the incident in Japan I wrote a comment on this blog site in favor of LFTR because of it’s several natural safety features that are superior to most other reactors. I consider those safety features hard to beat, so for that reason and for nearly unlimited energy supply these reactors can provide I support LFTR as our future reactor fleet.
    The concerns of Alvin Weinberg and many other engineers were vindicated by the events in Japan.
    I am strong supporter of nuclear power for over 40 years but I am also strong champion for nuclear safety
    I have to side with Kirk Sorensen about the concerns for the safety of proposed IFR. Beside several nuclear issues, the presence of extremely reactive liquid Sodium metal in air or water (contact with water produce hydrogen) does not meet natural safety criteria and is always subject to serious screw up under certain circumstances caused by forces in nature.
    Sorry, but I need more convincing before I will feel comfortable with a reactor that carry large fissile fuel critical mass, carry large quantity of flammable and reactive Sodium and works with fast neutrons.

    The only tragedy from this nuclear incident in Japan is that most likely all 6 reactors will be replaced by fossil burning generating capacity, contributing to climate change while continuously releasing radioactive elements carried by fossil fuels and the damage to nuclear industry image.
    Financial damage to TEPCO for lost power generating facility and extensive clean up is hard to estimate.

  33. @nkinnear Thanks for G estimate. I assume you are using water radiation absorpton factor f = 1.0, so Gxf = 0.45.

    I’ve seen estimates of 2 MW for R4 SFP heat. I estimate openspace to roof as 48mx48mx15m or 34,600 m3. At 4% H2 (min) that’s 1380 m3 H2.

    So for 2 liters/sec H2 for 2 MW and 4 days Mar 11 to Mar 15, Thats 690 m3 H2 from SFP radiolysis.

    In ballpark but still leaving room for possible Zr oxidation by steam, esp if you use 10% for H2 explosion, not 4% lower flammability level in air. Radiolysis also generates O2, so openspace may have had >21% O2.

  34. @ David Lewis

    My point is that you can calculate how much H2 is required for explosion in R4 building. You don’t need computer code to do that. Where did the H2 come from?

    Right now, we have two suspects: SFP Zr oxidation and SFP radiolysis.

    I’d be very happy to find some other suspects than SFP. I just can’t think of any.

    Some posters several days ago suggested R3 H2 finding its way into R4 building thru R3 ducting to commom vent stack between R3 & R4. Then backflow thru ducting to R4. This seems far fetched to me.

    One other suggested that the H2 came from the H2 dissolved in R4 reactor coolant circuit. I do not think that 100-300 kg of H2 could possibly be dissolved in that coolant.

    I remain open to other suspects and actually prefer that we find one. However we must follow facts where they lead regardless of our preferences/beliefs.

  35. NR99, on 25 March 2011 at 5:49 AM said:

    My point exactly, although we can quibble over the numbers

    Didn’t want to quibble (or maybe I did), but wanted to point that one in a million was not the correct number to be talking about, but the still low probability numbers when considered over a reasonable amount of time 100yrs. And I know this will go down with better designs, but we have to use the numbers we’ve got.

  36. I agree with Frank Kandrnal. LFTR can be designed to continuously and passively loose 1% of their heat so you always have cooling available, it is always on and you can depend on it.

    However I am also convinced that light water reactors can and many indeed have achieved sufficient passive cooling (or at least robust non-electric cooling) to survive monstrous earthquakes and tsunamis.

    For older BWRs I think a solution could be found in non-electric powering of emergency pumps such as steam turbine driven pumps. It appears that the Fukushima Daiichi plants still needed some electricity to power the emergency systems, I’m a little confused about this.

    For newer BWRs and PWRs also there are passive decay heat cooling designs which don’t need any electricity at all, they work by simple and redundant valves that have their own energy supply and even when they fail they will perform their function (which is to let steam or water through). Everything else is passive, natural circulation, condensation, boiling. These also have operational and regulatory simplicity advantages, reducing operations, maintenance and regulatory costs. Prime examples of this are the AP1000 (Westinghouse), the Kerena reactor (Areva) and the ESBWR (GE).

    So for newer designs its not entirely correct to say that they absolutely need electricity supply. For older designs, simple steam turbine driven systems can be made robust enough and passive enough to not require even a tiny amount of electricity (eg, autonomous energized valves with manual emergency functions etc.).

    Was it true that the Daiichi plants couldn’t operate the valves due to lack of battery capacity? This sounds unbelievable, anyone care to explain to me?

  37. there are multiple problems with this article, starting with the first sentence.

    strong conclusions can and MUST be learned from this event already today. this is a major nuclear accident in western type reactors. similar reactors are still in use and this must change in some way. the eassiest way to do this, is by switching them all of immediately.

    two workers got burned by water today, most people will be seriously concerned about this water leaking out of the Fukushima plant. and they are right to be concerned.

    basically every “may” in the text above must be changed into a “must”. it is a major lesson of the event, that storage of spent fuel inside the reactor is a massive error and must be reduced to the absolutely necessary minimum.

    the same must be said about reactors being sited close together. we also should switch of any reactors that can be damaged by H2 explosion in a neighbour reactor immediately.

    [deleted personal opinion presented as fact. Please re-submit with refs/links.]

  38. Frank Kandrnal, I like the liquid fuel reactor too, but you have to admit that the sodium-cooled fast reactor also has appeal. Using FUD tactics against one design in order to promote another doesn’t seem fair. That may be a stronger statement than is warranted, and please don’t take it wrong way; I just think it’s too early to focus on a single GenIV design to the exclusion of all others.

  39. @CyrilR re valves at Daiichi not operable due to lack of battery power.

    In petroluem industry, 3 types of valves: 1) manual valves usually block valve or isolation valves;

    2) Pnuematic valves opearated by air pressure from plant air systems. These are usually control valves up to maybe 8″. Plant air systems need air compressor running. Critical valves may have emergency air tanks if air supply lost. However, in this case, theycan be used to open/close valves a limited number of times.

    3) Motor operated valves (MOV) on large valves & lines. These are run by small electric motors. Emergeency valaves may be on UPS. Uninterupted Power Supply.

    What happens when UPS is gone? MOV then can only be moved manually. This can be hard to do for large valves and impossible after explosion or if high radiation in area.

    PS remote closing of air or motor operated valves need a functioning instrument system, also run on UPS. Instrument systems may not be working after UPS down, explosion or control room without power or inaccessible.

  40. NR99, we agree concerning AGW, but I’d not use the word “believe” to describe how I feel about it. :) Besides, even if something had to be done, the world is hardly united enough to carry it out in unison (another danger of nuclear power–rogue states or non-states).

    I’m fascinated by nuclear tech, even though I think its dangers are minimized around here. For example, it would be nice if when we did get one of those “unheard of” natural disasters, we did not *also* release radiation in the air.

    My problem is with risk and effect assessments, but American beat me to it. The simplification of exclusively using number of deaths is misleading and very convenient. Incidentally, the effects of radiation on the environment are rarely discussed here, which is ironic.

    Anyway, aside from the obvious bias, great information on this site (not only from Barry and guests, but most posters).

  41. @Leo Hansen – I’m just wondering whether a propagating zirconium fire could have mobilized a substantial portion of the cesium in the rods so that it became an aerosol and left the site as a plume to go where the wind blows. It clearly did not happen, this can be ruled out now. I’m just wondering if that last barrier to uncovering all water from the rods, i.e. the one wall where the concrete fell away leaving only the inner stainless steel liner, what if that failed so that it would then be impossible to keep water in the pool, what is a credible description of what would happen at that point.

  42. Great post Dr Hannum, thanks. I think a few additional “lessons learned” should be added:

    1) Radiation from a reactor prevent operators to reach the other reactors.

    => build plants with more distance between reactors

    2) Spent fuel pools are too vulnerable

    => rethink the spent fuel pool design and maybe add a containment vessel just for them

    3) Venting causes explosions

    => rethink the venting system design and avoid hydrogen accumulation in the buildings

  43. Lets take Barry’s upper estimate of a required 10 TW worldwide. let’s assume we’ll need this amount for 100 years until we get something better than fission. That’s 1 exawatt years of running time. According to the UK nuclear regulators, the EPR should have an accident causing >100 casualties once per 6E8 years. Do the math, that’s a 1 in 600 probability. Can we live with this risk? I think so.

    On Fukushima, I think we were lucky, as the majority of the release was blown out to sea. What puzzles and troubles me is, what is the source of such a large release? Why has it been so large? Is the containment damaged on one of the reactors? Is it the spent fuel.

    On the issue of what can we learn from Fukushima, I think its obvious that back up cooling provisions must be better defended from external hazards (as they are in the EPR and AP1000 design).

  44. sod, you seem anxious for a rush to judgement. Perhaps you are afraid that the evidence, once collected and examined, will not support your one-sided assessment? I notice that you pay no attention to the adverse consequences of your proposal – and if you haven’t thought about them, or claim there are none, you know nothing about risk.

    It is NOT TRUE that “two workers got burned by water” – they went to hospital to be checked over after contaminated water got through their clothing and exceeded their dose limit. And the water was not leaking out as such – they were inside the plant.

    Your point about the proximity to the sea is slightly odd… surely the proximity to the sea is what killed the reactors? So reactors on inland river systems would be less vulnerable. [ad hom deleted]

  45. Seamus

    I did not say I am totally against IFR. I am saying, I need more convincing that IFR can meet natural safety of LFTR. I am very much aware of IFR potential, however the same result can be achieved with LFTR.
    In addition, many more LFTR’s can be started with available fissile fuel and then run on Thorium.
    [personal opinion presented as fact]

  46. [deleted unsupported hearsay. Please re-submit with links/refs.]
    the risk assessment we have to do now, is about reactors that are similar to the ones used in Fukushima.
    i am in favour of having different opinions and i agree with many points made by Barry Brook. i come to this site, because i think it does present important information that is rare on other sources on the web.

    but there is stuff that is a fact, and not an opinion. spent fuel rods should NOT be stored on the top level of a nuclear power plant. this is simply a very bad design error, and it can and must be corrected immediately.

    the H2 explosions could have done enormous damage to the reactors. it is completely inacceptable, that “cutting holes into the roof” is our state of the art countermeasure to such a dangerous event.[deleted personal opinion presented as fact]the nuclear accident was caused by a lack of power. that this lack of power was caused by a tsunami in this specific case, is not relevant for learning lessons from this event. ([deleted personal opinion presented as fact]but most nuclear power plants are NOT based on sea site and could NOT simply release contaminated water into the sea. [deleted personal opinion presented as fact.]

  47. @ David Lewis 7:05 AM

    I don’t think fires (as commonly thought of) happen to the Zr cladding. It is possible that rapid oxidation of Zr to ZrO2(s) can occur if cladding is 1000C and steam is present. A fhin film of ZrO2(s) is left on the cladding surface, acting as a barrier to further steam oxidation.Thinning and rupture (by internal rod pressure) of cladding is possible if this ZrO2 film is flaked off or blown off by steam generated when water sprayed hits the cladding. The cladding is only 0.032 inch thick.

    Is this a credible description of what happened…well maybe possible description, but I don’t think that it is a “credible description” if this means supported by direct evidence.

    I also have not seen any evidence of large scale Cs etc l emission from SFP 4. I think we’ll have to wait and see what the final report on this are.

    Water loss in SFP 4 thru leaks in SS liner post Mar 15 explosion is possible. Also it is possible that the R4 SFP draining gate seals were damaged during the earthquake and subsequent power loss( see http://allthingsnuclear.org/ Mar 19). From the drawings in that site, water could have been lost down to just above the fuel assembly tops, possibly as soon as Mar 11. This would be in addition to any water lost be evaporation.

  48. re William Fairholm, on 25 March 2011 at 6:29 AM

    I think it is very valid to quibble over the numbers. The one in a billion was one person’s opinion. My main point was that before we can even “productively quibble over the numbers” all sides of the debate have to agree that a death is a death regardless of cause, some deaths are not preferable to others, and all forms of energy involve risk of death or injury in some way.

    We are far from arriving at that first point, as evidenced by those such as chris_warren, who argued endlessly here about his “zero tolerance for radiation” among other things, suggesting some deaths, in great quantities, are preferable to others. [deleted personal attribution of motives]
    I have trouble wrapping my arms around the idea of 50,000 people passively hanging around to get killed by radiation. It requires not only a huge amount of radiation, but also an inability to get out of the way. In the case of Fukushima, the earthquake and tsunami created a set of challenges for mobilizing the population that would be hard to duplicate. Yet even with those extreme challenges it appears that 200,000 people were efficiently evacuated from the area in a short period of time.

    It might be argued that that would be more difficult to do in Tokyo, but then there are no reactors on the outskirts of Tokyo, presumably for those reasons. It would probably be a good idea to keep that in mind should 2000 reactors ever be built.

  49. Ah well I see that my understanding of nuke power insurance had been painted with a far-too broad brush and I appreciate those above who have noted some of the finer details.

    Spurred by same however I spent the minute or so that I could spare looking into the question further and Wikipedia has great pages talking of U.S. insurance for nuke plants which, if accurate, might still kind of leave the validity of my question in place.

    That is, the Wikipedia pages (I’ll link at the bottom) note the existence of an indemnity law in the U.S., essentially and as a “bottom line” says that indeed the U.S. would assume any excess liability over and above some mandated coverages imposed on nuke plants. And I note that this law was not that long ago re-authorized by the U.S. Congress.

    So it would indeed seem from this that US nuke plant operators were—and still are—unwilling to go forward just getting the kind of insurance they could get from the private market, period. And indeed that’s exactly what Wiki said lay behind that indemnity law. (Saying further that while the original idea behind this 1950’s law allowed it to expire in the 1960’s—by which time it was thought plant safety would be proved and therefor insurable, the thing has in fact been continually extended on and on now to 2017 because that’s just not the case.)

    So, why isn’t the original question that I posted still valid? I.e., since nuke power can’t get enough private insurance to have people build and operate its plants, that this says something devastating about the risks involved?

    After all, I’ve heard the argument go, for all those people who feel they’re so safe, well, it’s easy to just *say* so, but when it comes to putting one’s money where one’s mouth is, well, neither they nor anybody else is willing to actually *bet* on same via insuring them. (Beyond the limited degree now noted, I guess the argument would go.)

    In any event here are those Wiki links (the first being very interesting beyond just talking about insurance, I would note):

    http://en.wikipedia.org/wiki/Economics_of_new_nuclear_power_plants

    http://en.wikipedia.org/wiki/Price-Anderson_Nuclear_Industries_Indemnity_Act

  50. Dr. William Hannum wrote:

    “In this way, the reactors were maintained in a relatively stable condition, allowing the water to boil, and releasing the resulting steam to the containment building.”

    [and later]

    “When vented to the containment and then to the outer building, the hydrogen built up, and eventually exploded, destroying the enclosing building.”

    Could someone please describe the direct pathway for this in the Mark I BWR containment design? Why would you vent radioactive gases and steam into what is essentially the work area of the reactor building for loading and off-loading fuel, component storage, and other plant design servicing tasks?

    As far as I know, there are multiple safety and back-up systems for dealing with pressure, steam, and residual heat in the Mark I containment vessel design, but they all take place within closed loop systems or vent “outside the reactor building.” This would seem to point to several important oversights in Dr. Hannum’s account?

  51. Good writeup on what we know as fact for now.

    Original emergency power supply designs need to be upgraded for defense in depth for beyond design basis events. That doesn’t necessarily mean they need to be safety related though, just more of them….

    You can’t design or build a safety related beyond basis backup power supply… Much the reason duel fuel gas turbines were eliminated from most plant designs. Though they require no cooling….

    Mindset was, most reliable and proven was diesel engines….

    Batteries as installed were of the same design event scope problem (time needed and availability…)

    The containment venting issue (hydrogen and pressure) will be a complete industry re-think. The facts have to be fully uncovered and released first though to solve the issue.

    Modifications are almost inevitable. Based on the preliminary data, requiring a hard piped elevated containment vent that will work with a complete loss of normal ventilation power.

  52. @Leo Hansen read the chapter on Spent Fuel Pool Storage in this NAS NRC 2006 report http://www.nap.edu/catalog.php?record_id=11263 then tell me propagating zirconium cladding fires are not possible.

    All commenters recognized as commenters by the panel who had their comments considered, some of whom disagreed with how grave the consequences could be or how likely it was, accepted that the scenario was possible.

    The panel was an National Reserach Council (part of the NAS) panel tasked by Homeland Security and Congress to tell them if a propagating zirconium fire was possible.

    I’m just wondering how to determine what else needed to happen or be in place at unit 4 in order for this possibility to be credible there.

  53. William Fairholm, on 25 March 2011 at 3:38 AM said:

    One thing I haven’t seen talked about is who is going to pay for the cleanup of these reactors. Is TEPCO going to go bankrupt doing so? They have already suspended their dividend and profit projections (go to their site). This is not even considering liability claims. Does Japan have laws limiting liability as have been passed elsewhere?

    Japan banks to lend TEPCO $24bn

    Get to Know Tepco: Japan’s Biggest Power Company

    Tepco Annual Report 2006

    2006 was the latest Annual Report I could find in English. The last page shows the major stock holders, the only non Japanese institution is State Street, but there will be others of course. There may be an SEC like regulatory filing, but its going to in Japanese.

    Japan’s financial situation is nowhere near as many would have you believe, much of the government debt is held domestically, and the domestic savings are very large and its foreign investments are huge.

    This is evidenced by the Japanese bond rates, i.e. the interest rate Japan pays on its borrowings. The Japanese 10 year bond rate is 1.21%; by comparison: UK is 3.58%, Australia is 5.45%, US is 3.4%, Germany is 3.24%, Ireland’s is a whopping 10.1%.

    I imagine the costs arising from what’s happened at Fukushima will be a fairly small fraction of the total costs arising from the earthquake and tsunami, and “at the end of the day” it will be the people of Japan who will bear most of those costs one way or another.

    Finally thanks to Barry Brooks for publishing this straightforward summary of lessons so far learnt,

  54. The lesson is:

    When warnings are given – act on them.

    Todays Sydney Morning Herald, pg10 reprints a Washington Post article.

    “Warning of tsunami threat to nuclear site was dismissed”

    This was in June 2009.

    The mentality behind this dismissal” and its meaning is absolutely vital.

  55. Why would you vent radioactive gases and steam into what is essentially the work area of the reactor building for loading and off-loading fuel, component storage, and other plant design servicing tasks?

    Because in a fully functioning plant (with AC available), you have an air purification system called the standby gas treatment system, which is designed to deal with the release of radioactive steam and hydrogen to the secondary containment. It consits of a recombiner to remove any hydrogen, then a dryer to remove moisture, an activated charcoal filter, which absorbes xenon, iodine and other active gases and then a HEPA filter that removes particulate contamination, and fans to finally push it out of the stack (elevated release) to ensure that any remaining activity doesn’t threaten operations in the plant area and gets dispersed effectively.

    The reason why you may have to release first to the secondary containment and not directly to standby gas treatment is that the gas pressure is too high if it’s not mixed with a large volume of secondary containment air first.

    The “reinforced direct vent” modification however bypasses the standby gas treatment and goes directly to the stack, and it appears it was installed in Fukushima as of 2002. I haven’t seen any official reports about using this system or why it hasn’t been used, if it wasn’t.

    According to a piping diagram released by TEPCO (sorry, again Japanese text only, look at the bottom image), there are four valves that need to be configured to use it.

    When the reinforced containment vent pipe is isolated from the SGTS and direct ventilation line, there is a pressure disk valve as the final seal, which the steam pressure from containment will break if the pressure is high enough. If it isn’t high enough to break this rupture disk valve, then presumably the pressure is low enough to be handled by the SGTS. That shouldn’t have been a problem with pressures reaching containment design pressures though.

  56. Excellent new information.

    All US nuclear plants take $300+million of private liability insurance,

    http://www.nuclearinsurance.com/

    But can you cleanup and rebuild a plant for $350 million, and pay compensation (if any) for radiated brave workers who responded to an event?

    $350 million is easily affordable if 1GW of electricity is sold. Given all the regulation, the premium would only be $1000000 or less.

    IE – less than 1 in 350 plants will need $350 million recovery each year.

    This is affordable.

  57. @ David Lewis 8:41 AM

    As I have said above, I believe that Zr cladding fires (as fires are ordinarly thought of with flames and oxidation in the vapor phase) are not pssible. To vaporize Zr, you need a temperature of 4400C.

    However, I believe that rapid oxidation of hot 100C+ Zr metal cladding surfaces by both H2O and O2 is possible when the cladding is no longer covered by water and if the internal heat generation is high enough. This oxidation should generate a thin film of ZrO2(s) which acts as a barrier to further oxidation. If this barrier is disrupted in some way, further oxidation of the newly exposed Zr metal surface can occur.

    Is this possible to such an extent as to generate a very rapid self-sustaining and propagting Zr surface oxidation (aka “fire”)? The report indicates that this may occur but is dependent on the many variables – the number and arrangement of fuel assemblies and on how much heat is generated by each fuel assembly and how efficient any water/air cooling is.

    To me, the events and facts as I know them (incompletley to be sure) indicate that the fuel assemblies in the R4 SFP did generate enough H2 (by H2O oxidation and radiolysis) to have caused the Mar 14 R4 building explosion. There may be another way to have enough H2, but I don’t know what it is.

    Have the R4 SFP fuel assemblies been in a situation caused by low water levels or loss of water to overheat and oxidize the Zr cladding such that the cladding has ruptured and released amounts of radioactivity? It seems to me that this is possible, but I don’t have the data to determine if this has happened or to what extent.

  58. It should be pointed out that some non-nuclear hazards have been indemnified by governments. In Australia the stand-out case appears to be CO2 escape from under Barrow Island WA

    http://www.watoday.com.au/wa-news/wa-and-commonwealth-to-share-gorgon-load-20090817-endr.html

    The operator Chevron will separate and pump up to 120 Mt of CO2 into saline aquifers. After that it’s not their problem if there is some kind of rupture.

    An unsettling aspect of Fukushima was not so much air borne particles but the backwash into the sea from hosing down. That takes the problem from not just not-in-my-backyard to not-on-my-coastline. Coastal residents 100km from a NPP site feel threatened.

  59. HR99 indicates:

    as evidenced by those such as chris_warren, who argued endlessly here about his “zero tolerance for radiation”

    I cannot find the reference for this.

    BUT

    we should be concerned about man-made INCREASES in background radiation.

    I speculate that normal radiation probably drives the needed mutations that gave us evolution (and rare birth defects all through history).

    But we do not want “increasing” background radiation.

  60. Bloomberg:

    http://www.bloomberg.com/news/2011-03-24/nuclear-safety-lessons-start-with-manholes-axes-commentary-by-peter-coy.html

    “… The new Westinghouse AP1000 … has a huge emergency water reservoir above the reactor vessel that’s held back by valves.

    If the cooling system fails, the valves open and a highly reliable force takes over: gravity. Water pours down to cool the outside of the containment vessel. Then another highly reliable force, convection, kicks in. As the water turns to steam, it rises. Then it cools under the roof, turns back into a liquid, and pours down again.

    Westinghouse estimates that the pool contains enough water to last three days, after which pumps operated by diesel generators are supposed to kick in and add water from an on-site lake….”

  61. David Lewis, on 25 March 2011 at 8:41 AM said:
    read the chapter on Spent Fuel Pool Storage in this NAS NRC 2006 report http://www.nap.edu/catalog.php?record_id=11263 then tell me propagating zirconium cladding fires are not possible.

    The report looked at loss of coolant in a densely packed spent fuel pool immediately after a full core offload.

    It would appear there was some disagreement as to whether moving fuel to dry cask storage or a separate pool after 5 years has a safety benefit.

  62. Here’s that Sydney Morning Herald/WaPost article, thanks for mentioning it:

    http://www.smh.com.au/world/warning-of-tsunami-threat-to-nuclear-site-was-dismissed-20110324-1c8lj.html

    “Warning of tsunami threat to nuclear site was dismissed
    David Nakamura Chico Harlan
    March 25, 2011
    TOKYO: A Japanese government agency that spent several years evaluating the Fukushima Daiichi nuclear plant declared the facility safe after dismissing concerns from a member of its own expert panel that a tsunami could jeopardise its reactors.
    In June 2009 Yukinobu Okamura, a prominent seismologist, warned of a debilitating tsunami …”

    Searching on his name in Scholar brings up a great many sources, e.g.

    http://hol.sagepub.com/content/18/4/517.short

    Marine incursions of the past 1500 years and evidence of tsunamis at Suijin-numa, a coastal lake facing the Japan Trench

    http://escholarship.org/uc/item/2nz5m9bs

    Water Resources Center Archives
    University of California
    Tsunami Information Sources: Part 2
    Wiegel, Robert L., University of California, Berkeley
    Publication Date: 04-18-2006

  63. @Mike. I suspect you would agree that a “zero tolerance for radiation” is about as silly as a zero tolerance for sunshine. Both are ubuiquitous and arguably necessary for normal life.

    Do we want increasing background radiation? I don’t know. People in various cultures have been seeking out deliberate exposure (though unknowingly) over all of history through their patronage of health spas- many of which have extreme levels of radon.

    Also, we should all be aware that background radiation on Earth was significantly higher over much of its history owing to higher levels of radioactive isotopes which have progressively decayed.

    I do not know if human-induced radiation has added to the whole-earth background to the extent that it changes this overall secular decline and I would be interested if anyone has seen any calculations on that.

  64. Pingback: Massive quake/tsunami in Japan - Page 18 - MBWorld.org Forums

  65. robguima, on 25 March 2011 at 7:01 AM said:

    “My problem is with risk and effect assessments, but American beat me to it. The simplification of exclusively using number of deaths is misleading and very convenient. Incidentally, the effects of radiation on the environment are rarely discussed here, which is ironic.”

    robguima, why is using number of deaths misleading and “convenient” (whatever you mean by that)? What else should be considered in an objective analysis?

  66. Pingback: The fearsome nuclear reactor meltdown accident « SeekerBlog

  67. Andy, on 25 March 2011 at 1:04 PM said:
    “Cost of insurance and liabilities should be considered in an objective analysis.”

    Isn’t that an issue for the plant’s accountants? I don’t think that is a public policy issue.

  68. This is a link to course material on nuclear safty. It explains what design basis accidents are and how they are designated. This should be useful to give some background on how safety design is done that anyone can understand.

    http://www.unene.ca/un803

    The material is in Chapter 2. The provider is University Network for Exelence in Nuclear Engineering. They are a consortium of universities in Canada. I have no relation with them. At the bottom of the page is an IAEA document titled Safety of Nuclear Power Plants: Design.

    i hope this helps provide a common reference point as this discussion goes on.

  69. Dear Barry and Dr. Hannum, or others with solid knowledge of the BWR ECCS system functions;

    It seems to me that the primary issue here in terms of failure isn’t the loss of power. That was planned for and in the design. Even so, the one thing I’ve yet to see, and have asked about several times hoping for an answer from someone knowledgeable about these systems, is why the high pressure ECCS injection systems failed in at least unit 1 and 3. As I understand it, they work strictly from the decay heat steam turning a smaller separate turbine. They are not reliant on off site power or on site power (diesels or batteries).

    Now I understand that once the water in the reactor system, torus, and suppression pool are hot enough, this system is no longer effective. At that point it would drop out and the low pressure systems come into play, powered one would hope by either battery or diesel.

    In units 1 & 3, however, ECCS was reported as being lost approximately 1 hour AFTER the tsunamis took out the diesel generators. I find it hard to believe that this system is only functional for about an hour… and if that is the case, how did Unit 2 manage to keep ECCS working for another full day or two? I could see how EQ damage or chance could cause one of the pumps powered by the turbine to fail, but not in 2 units, at right about the same time.

    There must be information available regarding the expected time period that the ECCS high pressure systems would be expected to function from the starting point of a SCRAM (for whatever reason). I find it very hard to believe that time would be only an hour…..

    Would someone please address this? Or would anyone who thinks they may know someone who could answer this, ask them and pass the answer back? If I’m off base here or have missed something, please, straighten me out – because this aspect is driving me crazy, even more so because I’ve not seen it addressed at all in article after article, and yet it seems to be such a key issue.

    Thanks so much in advance for any enlightenment!

  70. NR99 wrote:

    “robguima why is using number of deaths misleading and ‘convenient’ (whatever you mean by that)? What else should be considered in an objective analysis?

    Given that Rob seems to have been taking off from one of my posts, I suspect, NR, that by “convenient” Rob meant that same artificially is pro-nuke in that it ignores all the other kind of damage that nuke power accidents can inflict. E.g., rendering land uninhabitable with all the loss of property and jobs and etc.

    “Isn’t that [cost of insurance and liabilities] an issue for the plant’s accountants? I don’t think that is a public policy issue.”

    Well but it *is* a public policy issue (in the U.S. at least) given that not only was special U.S. legislation needed (requiring the pooling of assets from nuke plants) to provide a certain amount of liability insurance—with this itself involving some public policy decisions—but with that not even being enough to entice people to build and run nuke plants. Consequently the legislation had to make an even more direct public policy decision by agreeing to have the government indemnify any nuke plant losses exceeding the insurance provided. Or, in other words, putting the taxpayers on the hook.

    Maybe it’s just been missed but it’s interesting to me that the question I asked way up above hasn’t gotten some (or any?) answers when I figured there were some good ones out there.

    That is again … okay, accepting that yes, nuke power has its big benefits, it still has its risks, so given (in the US at least) that nobody will take those risks and insure against them, why shouldn’t this kind of be … the final answer for nuke power? That … sure, there are some who feel the risks are so slight of anything major that they advocate it, but … there simply aren’t enough of such people to capitalize an insurance company to actually take that bet. And, if the risk of having to pay out anything big is small, and there’s huge money to be earned in premiums, well why shouldn’t the fact that even huge money can’t entice takers be regarded as the best possible judgment on nuke power as possible at least? It can after all be looked upon as reflecting the collective, consensus opinion of everyone. So why should the opposite conclusion of just a few trump that?

    Not saying that *I* think this is a conclusive argument, and indeed I suspect there’s good arguments why governments *should* indemnify or perhaps even just cap nuke power liability to a degree, but I can’t put my finger on ‘em real definitively and I would have thought someone here would given that this is an old anti-nuke argument it seems.

  71. @ American,

    Regarding the insurance issue – in addition to the other excellent points folks here have made, I wanted to point out that insurance companies do not decide if they will or won’t insure based on the risk of something occurring. They decide what the total cost could be to them should something occur. The USA at least has become extremely litigious. People are so scared of radiation, understand it so little, and it is a complicated subject, that the possibility of a large number of frivolous lawsuits is very high. In other words, it’s not about how risky a reactor is mechanically – it’s about fear and litigation at least to a significant extent.

  72. Folks, you might be interested in this short video from the US Nuclear Energy Institute about spent fuel pools and lessons learned from Japan:

    They also have a brief article on actions already being taken by the US nuclear industry as a result of the situation in Japan:

    http://nei.cachefly.net/newsandevents/information-on-the-japanese-earthquake-and-reactors-in-that-region/nuclear-energy-industry-actions-to-ensure-continued-safe-operations/

    Some might also be interested in this brief and more basic video about spent fuel pools: http://www.youtube.com/watch?v=QO-daVysLH8

  73. American and Mike:

    All US nuclear plants take $300+million of private liability insurance,

    http://www.nuclearinsurance.com/

    I don’t know how you are doing it, but you are not reading or relating the rest of th requirements: that each operating reactor is liable for secondary premiums if the cost of an accident at the primary site exceeds $375M. Currently, the secondary amount maxes out at $12.6B. If the $12.6B is not sufficient, Congress can required the nuclear industry to pay more. So there is no government subsidy, just a gigantic insurance pool and legal limitations. While some may argue that the legal limits in regards to lawsuits is unfair, it makes sense to me, since all reactor designs and sites are approved by the NRC.

    (Aside: The NRC collects 90% of its annual operating budget from both operating fees (currently $4.5M per reactor, regardless of size) and licensing & inspection fees. According to Rod Adams, attempting to get a new design licensed cost $250K + $250/hr with no cap.) End Aside.)

    http://www.nuclearinsurance.com/Media%20Center.html#Limit Scroll down to “ANI Increases Domestic Liability Insurance Limit”

    Also described at http://www.nei.org/resourcesandstats/documentlibrary/safetyandsecurity/factsheet/priceandersonact/

    http://neinuclearnotes.blogspot.com/2008/09/price-anderson-act-explained.html

    http://neinuclearnotes.blogspot.com/2007/09/truth-about-price-anderson-act.html

    From a quick search, it appears that the total cost to decommission and cleanup TMI-2 was $975M. I’m sure that the rate payers of three owning utilities got stuck with the tab for that over the long run, just like they had to pay for TMI-2’s construction, even though it ran for just over a year before the accident.

    According to this link http://en.wikipedia.org/wiki/Three_Mile_Island_accident , $229M was placed in escrow for further radioactive decontamination when TMI-1 is removed from service, apparently because some of TMI-2’s concrete is contaminated.

  74. Rational Debate, on 25 March 2011 at 2:48 PM said:

    Aside from the litigious nature of the American legal system there are some serious issues with fairly compensating those with health issues.

    Hypothetically, let’s say that an incident spreads some radiation and it is determined that as best science can determine there is an additional 1% risk of cancer or birth defects.

    (and there does not seem to be any solid known science behind that sort of estimate since science cannot apparently even agree if the effect is beneficial or detrimental, based on the hormesis controversy but for simplicity we will assume it can be done)

    If 10,100 cancer cases and birth defects then occur over the next x years, science can say that 100 cases were *likely* the result of the incident but science cannot identify those 100 specific cases.

    Now you have 3 choices to determine who is eligible for compensation:

    1. Pay nothing to anyone because no one can prove they were in the 1% group.

    2. Pay everyone full value.

    3. Pay everyone 1% of their loss

    (or some negotiated settlement somewhere in between, of course, but lets keep it simple for discussion’s sake)

    Under the best of circumstances it is an untenable situation. Given the USA’s legal traditions, option 2 is a likely outcome. No insurance company wants to get into the middle of that mess, nor could they determine ahead of time their estimated exposure since it would be based on the whims of the legal system.

  75. As a mechanical engineer by degree and trade(non-nuclear field) I would like to add my opinion to this article.

    It would appear that this incident has exposed some failure modes around a Mark1 BWR, and its ancillary systems located at sea level in a highly seismic area that were not properly accounted for.

    Things such as loss of onsite backup power, H2 generation and accumulation, tsunami and flood protection, and SFP durability are all topics to be evaluated once the smoke clears.

    People need to be careful of critiquing the design of these facilities and the emergency response. As an outsider with hindsight it is easy to find faults and say that you would have done better. I believe the term is “sofa quarterback.”

    [deleted personal opinion – please support with refs/links where possible. Open Thread is the place for un-referenced personal opinion]
    Yes, some aging plants may have to close due to changes in licensing regulations or high modification costs. At this point any costs or changes to regulations are purely speculative.

    Countries that were trying hard to shut down nuclear prior to this event will use this as another reason to do so. Countries trying to sell new reactors will use this to show off their new safety designs. Countries on the fence will stay on the fence.

  76. re post by: NR99, on 25 March 2011 at 3:26 PM

    NR99, those same exact issues can be brought up with the output of all sorts of industries, either from normal operations, or from accidents. Many of them release chemicals or pollutants that are believed to be carcinogenic. They are all handled somehow. Concrete plants, incinerators, coal and oil and gas power plants, and so on. There are calculations for the increased cancer risk from them also.

  77. American, can you please stop [ad hom deleted]about nuclear plant insurance. When you agree that you were wrong about your initial statement, and that nuclear plants can and do buy commerical liability insurance to considerable value that covers the vast majority of possible liabilities, it might be worth discussing the ultimate limits of what insurance means and just how far the Price-Anderson limit changes that.

    But as long as you are basically ignoring reality, there’s not much point.

    NR99; there is actually a simple solution to health compensation – mandate national health care that is free at the point of use. Then the plants can compensate the government pro rata. Of course, that rational scenario is unlikely to happen in the US any time soon.

  78. @Rational Debate

    ‘ the US Nuclear Energy Institute about spent fuel pools’

    Decent video.

    Just as an aside as to where I’m coming from.

    I used to work military hazardous materials transportation and storage. Probably handled a few items a bit more dangerous then spent nuclear fuel.

    Rule #1 was to never mix hazard classes unless it was absolutely necessary.

    It didn’t matter to us that it was highly unlikely that a detonator could fly across a room, insert itself into a bomb casing and self actuate and set off a bomb off.

    We stored detonators and bombs separately

    The reason we stored them separately is they represented different risk categories. When things go horribly wrong, not having to worry about risk category ‘C’ is just one less thing to worry about.

    Sorry, but from my less then informed perspective, high density fuel pools are a bad idea. In normal nuclear plant operation there are 3 hazard classes.

    The active fuel in the core, the recently offloaded spent fuel, and spent fuel that can be stored in dry casks.

    The reason we did this

  79. Rational Debate wrote:

    “insurance companies do not decide if they will or won’t insure based on the risk of something occurring.”

    I guess I don’t understand what you mean, Rational. Of *course* they do, all the time, no? Indeed that’s *what* they do, isn’t it? They don’t assume every driver is, yes, going to be negligent and cause catastrophic liability, right? They play the odds. They give insurance “based on risk,” right?

    I’m not following I guess.

    “The USA at least has become extremely litigious. People are so scared of radiation, understand it so little, and it is a complicated subject….

    So? The more people who are unreasonably scared of something the more the opportunity, right? Say that people are terrified of getting hit by meteors. Wonderful. Great. I’ll be more than happy to insure ‘em against same and take their gobs of foolishly spent dough.

    “the possibility of a large number of frivolous lawsuits is very high. In other words, it’s not about how risky a reactor is mechanically – it’s about fear and litigation at least to a significant extent.”

    But wait a minute: how is that different from any other thing/bad event? And yet, there is insurance for many if not most of same. Why? Because all those things can be and are taken into account. (Via, among other things, premium prices.)

    Paul Lindsay wrote:

    “So there is no government subsidy, just a gigantic insurance pool and legal limitations.”

    No Paul, I don’t think that’s accurate, at least as per Wikipedia. The U.S. law is expressly entitled the “Price-Anderson Nuclear Industries *Indemnity” Act,” because it essentially provides that if the coverage it mandates for nuke plants is exceeded due to a nuke plant accident or etc., the gov’t *can* make all other nuke plants chip in to cover same and, if that’s not enough or they don’t want to do that, then the Gov’t *itself* will provide an indemnity to make it up.
    See:

    http://en.wikipedia.org/wiki/Price-Anderson_Nuclear_Industries_Indemnity_Act

    So once again we are back at the apparent point of it simply being the case that, unlike most other activities, not enough private people (read “insurance companies” or “people who might form such companies”) feel that the full risk of nuke power liability (“frivolously” imposed or not) is such that it is outweighed by the enormous rewards that would come from same. And hence the government has to step in to provide indemnification before anyone will build and operate those plants.

    Lastly, addressing NR99’s further comment about the idea that the U.S. would somehow make an insurer pay full value to 100% of claimants even though only 1% suffered, well then I agree nobody would insure that. *But that’s not the situation.* And if it was changed to make it so, then NR’s point would be valid and you’d see insurance companies dropping out of covering nuke plant accidents. But, again, that’s not the situation now, so something else must explain it I think.

    I dunno: While I think NR is wrong in his specifics I too was drawn to focus on the idea that there’s just something different about the *nature* of the risk of nuke plant accidents that makes insurance for them different. (And thus legitimately needing gov’t indemnification or capping liability or etc.)

    But … I can’t articulate it. After all one might say … “oh, it’s because while the risk is so small, *if* there is an accident the liability is so huge….” However, the magnitude of potential liability is *always* taken into account in any insuring situation, and is provided for via the price of the premium. I.e., what amount of profit and reserve that’s necessary to induce people to extend insurance for something.

    I dunno. Maybe one just has to concede the anti-nuke argument that yes, nuke power is indeed just “riskier” (defined as meaning both chance and potential harm) than what private people are willing to bet on, no matter the foregone monetary reward, but that gov’t should still step due to the size of the benefit flowing to those not in the line of risk, period.

    A nasty equation, admittedly, but maybe the bottom line?

  80. re post by: American, on 25 March 2011 at 4:37 PM said:

    Rational Debate wrote:
    “insurance companies do not decide if they will or won’t insure based on the risk of something occurring.”

    I guess I don’t understand what you mean, Rational. Of *course* they do, all the time, no? Indeed that’s *what* they do, isn’t it?

    It all depends on what the specific thing being insured is, American. In general people aren’t unreasonably afraid of cars such that they’ll sue a driver for merely tossing a bit of trash out the window. So its not a good analogy.

    So? The more people who are unreasonably scared of something the more the opportunity, right? Say that people are terrified of getting hit by meteors. Wonderful. Great. I’ll be more than happy to insure ‘em against same and take their gobs of foolishly spent dough.

    Except we’re not talking about insuring people against the power plants, we’re talking about insuring the power plants against those very people who are apt to sue far too easily because of unreasonable fears and a lack of understanding (and a boatload of media sensationalizing that keeps stirring things up worse.)

    There are other large scale things that the government also indemnifies I believe. One I’m sure of is that in the U.S., flood risk is insured by the federal government… per: http://en.wikipedia.org/wiki/Insurance As are federal contractors.

  81. re post by: Geoff Russell, on 25 March 2011 at 6:00 PM

    oh man!

    t is thought that the workers ignored their dosimeters’ alarm believing it to be to be false and continued working with their feet in contaminated water.

    Thanks for the link to the update Geoff.

  82. American,

    Percieved risk is not actual risk. When there is no information or conflicting information then it is an insurance company’s duty to take the most pesimistic view presented.

    Essentially you are arguing a tautology. People are afraid of nuclear plants so insurance companies see them as high risk … since insurance companies see nuclear plants as high risk people should be afraid.

    MODERATOR
    Why is this whole long exchange not over on the Open Thread? I think it will be a long time before the lessons learned in Fukushima percolate to actuarial tables… just say’n :)

    MODERATOR
    I agree Joshua. However it started overnight Australian time and to delete all the long posts in the morning and ask them all to re-post seemed a little harsh.
    It could be argued that insurance problems will come up in the wash up from Fukushima and so this is not entirely off topic.
    Perhaps folks commenting on this aspect could switch to the Open Thread from here on in.

  83. In units 1 & 3, however, ECCS was reported as being lost approximately 1 hour AFTER the tsunamis took out the diesel generators. I find it hard to believe that this system is only functional for about an hour… and if that is the case, how did Unit 2 manage to keep ECCS working for another full day or two?

    According to NISA, reactor 2 lost ECCS on 1636 JST March 11th. I think you mean unit 3, which lost it on 0510 March 13th.

    One possibility is that for unit 3 venting of primary containment was started early enough (2041 on March 12th) to prevent suppression pool temperatures too high for ECCS (or more spesifically, HPCI) to function. DC power is needed for HPCI operation and I recall there being reports of charged batteries being hauled to unit 3 before the explosion there.

    The question of why HPCI failed within 2 hours of SCRAM (when the projected runtime on batteries was 6 hours), might be because those reactors had already been depressurised between the scram and the blackout and moved from RCIC to RHR cooling. That’s how you would “normally” attempt to reach cold shutdown after a scram, not expecting a tsunami to take out your station AC backup. IIRC RCIC/HPCI require about 350 kPa of reactor pressure for their turbo pumps to work, in addition to DC power for valves.

    There are only speculative possibilities, the final answer why the units had different paths to essentially the same end result, will probably take months to be investigated and published.

  84. I would like to adress the following questions to the experts:

    IAEA update log (24 March 14:00 UTC) http://www.iaea.org/newscenter/news/2011/fukushima240311.html
    According to the log there are 6 spent fuel pools containing slightly over 5,000 fuel assemblies. What is the difference (e.g. in terms of radioactivity and heat dissipation) between an irradiated and an unirradiated fuel assembly ?
    Also mentionend is the Common Use Spent Fuel Pool, but there are no data on its capacity and the number of fuel assemblies in it. Where is this pool located in the plant ?

    JAIF Reactor Status and Major Events Update 31 (March 24th, 2011 18:00) http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300976122P.pdf
    Why does the Common Use Spent Fuel Pool pool not show up in the JAIF status ? For Unit 1 there are reported two water levels und two reactor pressures (A and B). Does unit 1 contain 2 reactors ? For unit 2 there is one water level but two reactor pressures, can someone explain this ?

    Salt accumulation http://www.nytimes.com/2011/03/24/world/asia/24nuclear.html?_r=2&hp
    Prof. Richard T. Lahey Jr., who was General Electric’s chief of safety research for boiling-water reactors, expresses his concerns on the ongoing seawater injections. He suspects that salt crusts will grow on the fuel assemblies making cooling more and more difficult. Does it affect the assemblies in the reactors or in the fuel ponds or both ?

  85. Pingback: Preliminary lessons from Fukushima for future nuclear power plants « SeekerBlog

  86. TEPCO release data from a water sample taken from the turbine hall of reactor 3 after the “bootless contractor workers ignoring their dosimeter alarms” incident.

    Absense of fuel pellet elements (Th, U, Pu) is interesting.

  87. Good grief.
    This article in New Scientist can’t even handle exponents:
    ‘it has emitted 5 × 10 to the 15th becquerels of caesium-137 per day; Chernobyl put out 8.5 × 10 to the 16th in total – around 70 per cent more per day.’

    http://www.newscientist.com/article/dn20285-fukushima-radioactive-fallout-nears-chernobyl-levels.html

    They make exactly the same mess on iodine 131, giving 50% when it should be 5%.

    What hope for rational evaluation when a popular supposedly scientific publication not only makes this sort of error, but the sub-editors are too innumerate to pick it up?

    That is 7%, not 70%

  88. Apropos the insurance issue MODERATOR wrote:

    “Perhaps folks commenting on this aspect could switch to the Open Thread from here on in.”

    Switching….
    MODERATOR
    Thank you American for your assistance. Much appreciated.

  89. ‘The water three men were exposed to while working at the Fukushima Daiichi nuclear power plant had 10,000 times the amount of radiation typical for that locale, an official with the Japan nuclear and industrial safety agency said Friday.

    The contamination is likely from the No. 3 reactor’s core, the official, Hidehiko Nishiyama said.

    He said there’s a possibility of “some sort of leakage” — including potentially from a crack in the unit’s containment vessel.’

    http://edition.cnn.com/2011/WORLD/asiapcf/03/25/japan.nuclear.reactors/index.html

    Also from the same link:

    ‘Switching to fresh water, instead of seawater, is also a priority for the No. 2 reactor’s core (as well as for its spent fuel pool), said Nishiyama. The aim is to prevent further corrosion and damage inside, which may be worsened by the buildup of salt.

    Japanese defense minister Toshimi Kitazawa said Friday that a U.S. military ship filled with fresh water is heading toward the Fukushima Daiichi power plant. The ship will serve as a back-up for Japanese systems addressing the same problem, he said.’

  90. question for Moderator
    Can we have direction on where updates, questions on updates and related technical analysis should be posted?
    At the moment this stuff is scattered between 3 threads (open thread, preliminary lessons and 10+ days)
    I would suggest updates, technical analysis of updates and questions on new developments should all go to 10+ days

    MODERATOR
    I have passed this suggestion on to Prof Brook for his attention. It would be a full-time job to meticulously read each comment and make decisions as to the best possible thread and I am one part-time volunteer. Sometimes topics overlap threads anyway – a subjective judgement really.

  91. Tsunami Risk Well Known to Nuclear Engineers, Regulators Who Failed to Act

    Japan’s nuclear regulators and the operator of the crippled Fukushima reactors were warned that a tsunami could overwhelm the plant’s defenses and failed to recognize the threat.

    The Trade Ministry dismissed evidence two years ago from geologists that the power station’s stretch of coast was overdue for a giant wave. Tokyo Electric Power Co. engineers also did not implement lessons from the 2004 tsunami off Indonesia that swamped a reactor 2,000 kilometers (1,200 miles) away in India, even as they advised the global nuclear industry on how to cope with the dangers.

    more

    http://www.bloomberg.com/news/2011-03-25/tsunami-risk-well-known-to-nuclear-engineers-regulators-who-failed-to-act.html

  92. “Where did the hydrogen come from”

    Do we know where the atmosphere above the lead/acid batteries was vented?
    All lead/acid batteries vent hydrogen when discharged and the plants had an awful lot of them.

  93. Apparently the workers burnt were not wearing industrial boots:

    ‘The two hospitalised men, employees of a Tepco affiliate, were part of a team of six workers attempting to connect a water pump to the power supply and restart the supply of fresh water in an attempt to cool the reactor. Workers in the first and basement floors of the No 3 reactor’s turbine building were ordered to evacuate the area after the accident.

    Japan’s nuclear safety agency said water had probably seeped through their protective clothing, allowing radioactive materials to stick to their skin, as they stood in a 15cm-deep puddle. The two injured men were wearing shoes, while the third had boots on and so escaped serious injury.

    Radiation levels on the surface of the puddle were later measured at 400 mSv per hour, while the level in the air reached 200 mSv per hour.

    The source of the water was not immediately clear. Tepco said no puddle had been spotted in the turbine building the previous day. Fire trucks have been dousing the reactor in recent days in an attempt to cool a storage pool for spent fuel rods.

    The accident cast doubt on Tepco’s ability to properly monitor radioactivity at the site. “This kind of exposure, from water, was unforeseen,” the government’s chief spokesman, Yukio Edano, told reporters.

    “Atmospheric radiation levels are monitored constantly, but in this case the workers stepped into water. We are trying to find out exactly what happened so we can ensure it doesn’t happen again.”‘

    http://www.guardian.co.uk/world/2011/mar/24/japan-nuclear-plant-workers-hospital

  94. As Red_Blue mentioned, is there a reason for Th, U, Pu, etc, not being in TEPCO’s report? How can you have such extremely high levels of products without even a trace of fuel?

  95. Oh, man, I wish I’d heard that stuff about the two guys being contaminated last night… we had a safety standdown at work this morning, and it would have been a great example of what not to do!

    1) Incorrect PPE; and
    2) Ignoring warnings from instruments designed to warn of a hazard.

  96. @David Martin
    New Scientist is comparing one day at Fukushima with 10 days at Chernobyl. The daily amounts are close, so the Chernobyl totals are around one magnitude higher.

    I don’t see any problems with New Scientist’s numbers.

  97. Ah yeah, I made the same mistake with the NS numbers. So back to my earlier question: how has there been such a large release. Considering to possible graphite fire, and containment?

  98. “Tokyo Electric Power Co. said Friday it has begun injecting freshwater into the No. 1 and No. 3 reactor cores at the crisis-hit Fukushima Daiichi nuclear plant to enhance cooling efficiency”

    “although highly radioactive water was found leaking possibly from both reactors as well as the No. 2 reactor.”

    http://english.kyodonews.jp/news/2011/03/81116.html

    (posted with different IP, using a proxy, as internet has been working oddly in China. Cause >
    “ocean cables damaged in the Japan earthquake”

    http://www.shanghaidaily.com/article/?id=467194&type=Metro

    )

  99. Pingback: Nucleare: un referendum che non s’ha da fare | Ultime Notizie e attualita'

  100. It seems that studies involving the WWII nuclear fallout in Japan indicates that people exposed to low levels of radiation *live longer* and have *less* cancer than their non-irradiated coutnerparts.

    It’s the Hormesis effect: http://en.wikipedia.org/wiki/Hormesis Here’s a copy of the article:

    Lawrence Solomon: Japan’s radioactive fallout could have silver lining
    Lawrence Solomon Mar 21, 2011 – 10:56 PM ET
    Financial Post

    http://opinion.financialpost.com/2011/03/21/lawrence-solomon-reactor-victims-will-benefit-studies-show/#more-11924

    “The study’s bottom line: “the low doses of A-bomb radiation increased lifespan of A-bomb survivors.””

  101. I’m inclined not to take at face value such ballpark initial estimates of the volatile Cs-137 and I-131 source terms at Fukushima which are based on measurements taken at CBTBO monitoring stations, some of which are many thousands of miles away from the source, so that time delays, winds, and weather patterns all the way in-between have to be taken into account.

    Surely these estimates might be either high or low, based on the particular modelling that was used to extrapolate the point measurements of activity to get the total activity in the plume, and to plot that activity as a function of time as well: but if we take the NS article as accurate and complete, then it seems Wotawa attaches no error range whatever to his estimates.

    Altogether, that article surely doesn’t look to me like a scientific discussion of the data.

    For estimating the size of the source term, I would have thought it would be far better to rely on measurements of volatiles observed NEAR to Fukushima.

    In addition, it’s mentioned in the article that at Chernobyl far more fission products than Cs-137 and I-131 were observed. Yet Wotawa apparently does not report levels of any other products. Does that mean that there were none observed?

  102. Shelby, on 25 March 2011 at 10:29 PM said:

    Tsunami Risk Well Known to Nuclear Engineers, Regulators Who Failed to Act

    This was one of my first thoughts and I posted that somewhere maybe here (remembering back 2 wks), that a report would turn up underlining the tsunami risks for these reactors. As with all these reports, someone then makes a determination if the likelihood is great enough to spend money on correcting. They bet it wasn’t. Their decision will be analysed to see if this was reasonable. Given the tsunami risk (not large earthquake risk) I would say not.

  103. Since the guest post included some comments on relative safety of the sodium-cooled fast reactor, I’m interested again in what is known regarding the response that is likely from a molten salt reactor. I have read in the past that a very primitive safety system consisting of an electricity-cooled solid plug at the bottom of the reactor, which melts on a loss of power and allows the molten salt/fuel combination to spread in a catch basin. Will this type of design prevent any further damage from decay heat, etc.? Any of the local experts care to comment?

  104. ParetoJ, on 26 March 2011 at 3:41 AM said:

    It’s the Hormesis effect:

    One of the criticisms of the using nuclear fallout survivors in Japan for the Hormesis effect is that they may of been a selected population, i.e. the weaker people exposed to the bomb and immediate effects thereafter died, so you have people left who have higher natural immunity and whatever other characteristics that helped them survive. Given that the linear no-threshold model is a worst case model. As an analogy lets say you tap one million people on their hand. No effect right? Now the linear no-threshold model would say that would have the same effect as taking that energy and applying it to a few people, which would shatter their hand. Exposing a large no. of people to low dose of radiation is the same as exposing a few people to a large dose. Not very credible either.

  105. @ DocMartyn 25 Mar 10:31 PM

    Thanks for this idea on H2 generation from the numerous discharged batteries. I think it depends on where the batteries are located.

    If batteries were in R4 reactor building, batteries could have contributed H2 if vented to building top.
    If batteries are in the separate turbine hall building, then no.

    I’d guess that the batteries are in the turbine hall because that’s where the steam turbines, their surface condensers for condensing turbine steam and the main cooling water pumps (driven by batteries) are.

    However, that’s just a guess. Somebody with actual experience would have to tell us where the batteries are located.

  106. Thank you, Dr. Hannum, for a very complete overview of events at Fukushima. I have been involved with industrial chemistry for many years, and I take some issue with your acceptance of molten sodium as safe. In extreme events such as a 9.0 earthquake, it would not be out of the realm of possibility to experience a leak, possibly a large leak, of hot liquid Na. Even atmospheric water would be enough to generate hydrogen, and if there were a quantity of liquid water, it’s very likely there would be a large hydrogen explosion. All this can possibly designed-around, but I wouldn’t categorize it as “intrinsically” safe.

    Sincerely….JP Straley

  107. Since the safety systems kicked in and shit down the reactors, it sends much of the risk was posed by the spent fuel pools not being within containment. I have heard that spent fuel can remain as high as 90% radioactive. I am just an interested reader and not a nuclear scientist so I dont know if that is true. In any case, it seems we would want containment for the fuel pools. Is there a reason that was not part of the original design?

  108. The analysis by Gerhard Wotawa written up in the New Scientist is interesting in one respect: the levels of iodine relative to caesium suggest that the reactor cores of units 1, 2 and/or 3 are the source (and pretty much the sole source) of the long-range release – leaving its size to one side for now. Iodine-131 in 5 & 6 and in all the spent fuel pools would be basically non-existent, but caesium-137 would still be present at only slightly-reduced levels compared to the reactor core.

  109. With respect to the New Scientist article: it’s always a good idea to
    check the primary sources. The actual conclusions from Wotawa’s website
    are:

    Die geschätzten Quellterme für Jod-131 sind sehr konstant,
    nämlich 1.3 1017 Bq/Tag für die ersten beiden Tage (USA-Messungen) und
    1.2 1017 Bq/Tag für den dritten Tag (Japan). Für Cäsium-137 lassen die
    USA-Messungen auf einen Quellterm von 5 1015 Bq schliessen, während in
    Japan sehr viel mehr Cäsium in der Luft war. An diesem Tag würde der
    Quellterm mit etwa 4 1016 Bq abgeschätzt werden.

    Bei der Reaktorkatastrophe von Chernobyl war der gesamte Quellterm von
    Iod-131 1.76 1018 Bq, der von Cäsium-137 8.5 1016 Bq. Die für
    Fukuschima abgeschätzten Quellterme sind damit bei 20% des
    Chernobyl-Terms für Jod, und 20-60% des Chernobyl-Terms für Cäsium.

    Nachdem Cäsium-137 und Jod-131 nur einen Bruchteil der
    Gesamtdosisleistung in der Umgebung des Reaktors ausmachen, heißt das
    nicht, dass lokale Strahlenbelastungen in Fukushima so hoch sind wie
    in Chernobyl. Die Quellterme erklären aber die Belastung der
    Lebensmittel und des Wassers. Die Dosisleistungen von Cäsium und Jod,
    die sich aus unserer Quellhypothese ergeben, sind viel geringer als
    die insgesamt in Japan beobachteten.

    http://www.zamg.ac.at/aktuell/index.php?seite=1&artikel=ZAMG_2011-03-23GMT10:57

    My translation is (apologies, if there are errors, my german is quite
    a bit rusty):

    The estimated source terms for Iod-131 are very constant, namely
    1.3×10^17 Bq/day for the first two days (USA measurements) and
    1.2×10^17 Bq/day for the third day (Japan). For Caesium-137 the USA
    measurements allow to infer a source term of 10^15 Bq, while in Japan
    very much more Caesium was in the air. On this day the source term was
    estimated at about 4×10^16 Bq.

    In the the reactor catastrophe of Chernobyl the total source term for
    Iod-131 was 1.76 10^18 Bq, that for Caesium-137 was 8.5 10^16 Bq. The
    estimated source term for Fukuschima are so at 20% of the Chernobyl
    term for Iodine, and 20-60% of the Chernobyl-term for Caesium.

    Afterwards, Caesium-137 and Iod-131 made up only a fraction of the
    total dose rate in the region of the reactor, that doesn’t mean
    that local radiation exposure in Fukushima are as high as in Chernobyl.
    The source terms declare though, the exposure of food and of water.
    The dose rates of Caesium and Iodine, that result from our source
    hypothesis, are far smaller than the the total observed in Japan.

    So: there are no data as yet beyond three days, even from these, in my
    opinion, questionable estimation methods, and the New Scientist
    article should therefore not integrate the source terms up to ten
    days.

  110. Dr. William Hannum wrote:

    “In this way, the reactors were maintained in a relatively stable condition, allowing the water to boil, and releasing the resulting steam to the containment building.”

    [and later]

    “When vented to the containment and then to the outer building, the hydrogen built up, and eventually exploded, destroying the enclosing building.”

    These statements by Dr. Hannum need to be corrected. I raised the issue once before above, and nobody has followed up on it. But it is actually one of the main issues to be considered for this accident (venting and hydrogen management). There is no vent that leads directly into a major working area of the reactor building where fuel loading takes place and the spent fuel pond is located. This would be a major oversight in design, since this area is not kept free of oxygen and is no place to vent dangerous radioactive steam and gases.

    E&E Publishing (appearing in the Times) looks at this issue today: “U.S. Experts Blame Fukushima 1 Explosions and Radiation on Failed Venting System.” They consider two alternatives. The first is the one I initially suggested (based on Mitsuhiko Tanaka’s account of the accident presented at an expert panel event in Japan): a failure of the primary containment vessel at the hatch for the primary containment vessel which is designed to withstand 4 atmospheres of pressure (when the primary containment vessel contained 8 atmospheres at the time, or twice the amount of design tolerances). The second is a failure of the venting system, which works by moving steam and radioactive gas from the primary containment vessel through the reactor building, and to the large 100 meter emissions stacks located outside the power plants (which can filter and diffuse the gas to minimize it’s environmental impact). But as it turns out, these stacks require fans to work properly, and thus electrical power. The speculation is that “most, if not all, of this dangerous mix of hydrogen gas seeped into the reactor building in Units 1 and 3. The hydrogen, being lighter than air, mixed with air in the upper large refueling floor area” (and subsequently exploded). Clearly, this is going to be a vital issue in the subsequent dissection of this accident, and should give rise to an “industry re-think” (as suggested by em1ss above).

    Any additional thoughts on this important (and central issue) to this accident, are obviously welcome.

  111. But as it turns out, these stacks require fans to work properly, and thus electrical power.

    Standby gas treatment system requires fans to work when it’s taking air from secondary contaiment (reactor building outside of the primary containment vessel), since this air is normally at slightly under atmospheric pressure. If a steam/gas mixture of very high pressure (the kind of pressure that would threaten primary contaiment integrity) were to be discharged directly to SGTS, it would damage SGTS and probably leak to the auxiliary building instead of being vented out of the stack.

    The direct hardened vent installed to Fukushima reactor buildings doesn’t require any fans, if the discharged steam/gas mixture is of high enough pressure. The pressure must be high enough to break the rupture disk valve anyway.

    There are several scenarios of why this might not have been used, but we don’t know yet even if it was used or not. I can think of at least the following:
    – damage to valves from the quake or tsunami, and/or structural damage preventing access to the valves for manual operation
    – venting attempted at below the rupture disk pressure, or leaks before the rupture disk
    – deliberate attempt to reduce activity release by venting to the secondary containment instead, perhaps hoping that SGTS could be restored before reaching explosive concentration
    (the only “filter” for the direct vent line is that any material from the core would have gone through the suppression pool water first, with boil off from that water being of much lower activity)

    Before we can assess whether a containment vessel leak is to blame or venting operations, or even both, more information needs to be secured. Radiolysis from the pools as one source should not be completely overlooked either, as in normal operation that is effectively removed from the secondary containment air when ventilation (at a rate of about one full exchange per day) is working.

  112. In one of the threads there was mention that the Brown’s Ferry secondary containment vessel could not hold pressure at 70 psi (~4.5 atm) when they tried to pressure test it during construction. It leaked at the flange at the top of SCV. When they reduced pressure to 65 psi it held.

    Then somewhere else in these threads there is a long video presentation by one of the design engineers. In it he postulates that steam and hydrogen being vented from the PRV resulted in the reported SCV pressure of 8 atm (~120 psi) which is about double the design pressure of 3.7 atm. The hydrogen being the lightest component collected, at high concentration, at the top of the SCV under the dome and leaked out at the flange when the SCV internal pressure doubled the design pressure.

    This leakage would have vented the high concentration hydrogen gases directly into the operating floor penthouse at the top of the reactor building where it ignited with explosive force.

    His theory seems to give a credible explanation as to how the hydrogen got to the top floor of the building.

    I suck at searching in these forums so no links but I will post them when I find them.

  113. re post by: Red_Blue, on 25 March 2011 at 7:06 PM:

    Red_Blue, thank you for your reply! You are right that I was apparently flipping the units, and that it was 1 & 2 that lost ECCS about an hour after the tsunami.

    You may have in part answered my question – I was under the impression from a few different sources such as NRC that the RCIC ran solely by turbine – no battery or AC needed. From US NRC Reactor Concepts Manuel, Boiling Water Reactor Systems: http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf

    The reactor core isolation cooling (RCIC) system provides makeup water to the reactor vessel for core cooling when the main steam lines are isolated and the normal supply of water to the reactor vessel is lost. The RCIC system consists of a turbine-driven pump, piping, and valves necessary to deliver water to the reactor vessel at operating conditions. The turbine is driven by steam supplied by the main steam lines. The turbine exhaust is routed to the suppression pool. The turbine-driven pump supplies makeup water from the condensate storage tank, with an alternate supply from the suppression pool, to the reactor vessel via the feedwater piping. The system flow rate is approximately equal to the steaming rate 15 minutes after shutdown with design maximum decay heat. Initiation of the system is accomplished automatically on low water level in the reactor vessel or manually by the operator.

    I also found a DBA scenario for loss of offsite power (LOOP) + guillotine main line break – so perhaps not totally applicable but I would think close, since it appears the initiation of the emergency systems we’ve been discussing is the SCRAM + main line isolation. http://www.enotes.com/topic/Boiling_water_reactor#The_safety_systems_in_action:_the_Design_Basis_Accident It states:

    As a result, the RPS immediately initiates a full SCRAM, closes the Main Steam Isolation Valve (isolating the containment building), trips the turbines, attempts to begin the spinup of RCIC and HPCI, using residual steam, and starts the diesel pumps for LPCI and CS.

    But you’re saying that RCIC requires batteries for the required valves? If so, then I’m still confused because I thought that all three units had batteries?

    Let’s say that unit 1 & 2 had already shifted to the lower pressure RHR… both had battery power to run RHR for some time, didn’t they? So why would RHR have failed? Why would pressure have increased beyond what RHR could handle?

    Even if pressure did increase past what RHR could handle, couldn’t they have just switched back to high pressure RCIC?

    ~~~~~~~~~~~

    So, we’ve got:

    RCIC – high pressure, ??? driven – turbine driven (per NRC), battery (enotes), initiation on low RPV water level or manually
    HPCI – high pressure, diesel driven, initiation on loss of coolant
    RHR – low pressure, ?? driven, init ??
    LPCS – low pressure, ?? driven, init ??
    LPCI – low pressure RHR + CS, diesel driven, init ??

    So I’m still confused…

  114. Articles like this drive me crazy:

    Tokyo Electric’s sea-wall defenses for the Dai-Ichi plant were built under the assumption that the coastline on which it sat wasn’t prone to tsunamis higher than 5.5 meters….

    An 8-meter tsunami that hit Japan’s northeast in 869 swept as far as 4 kilometers inland at Sendai Bay, stretching south toward the Dai-Ichi plant….

    A repeat could occur soon because sediment samples showed the tsunami had a pattern of recurring every 800 to 1,000 years, according to a 2001 report by a research team funded by the government’s Science Ministry.

    It sounds oh-so-bad, those rotten people should have been better prepared for tsunami, they were warned!!

    Only a few problems if one reads with a bit of a well justified critical eye. First, the ‘well established’ historical precedent tsunami they note is specified for Sendai Bay and they don’t bother to tell us how high it was at the Fukushimi-1 & 2 sites where it could very very easily have been tremendously smaller. Next, we all tend to think “if it could be THAT large at x location, of course it could be at y location also” Only that isn’t true at all, because it all depends on where the fault lines are, how the ocean floor lays between those locations and the site of interest, what the elevation is at the site of interest, etc.

    So, if the next one was overdue, what would it matter if historically it wasn’t higher than the 5.5m already planned for at Fukushimi? But they never address that aspect, do they?

    But along those lines – I gather that the primary buildings & diesels were about 10m above sea level… where was the 5.5m tsunami/sea wall relative to those structures?

    Finally – they note that the historical information and warning about tsunami risk was presented. That it was deemed to not be a significant risk apparently. In cases like this where hindsite picks out one or even a few people who warned about some catastrophe and others didn’t act on it, all too often it turns out that it wasn’t acted on NOT because of greed, or negligence, but because a number of experts evaluated the situation and didn’t feel that it was nearly the risk being portrayed. Only reports like this never bother to go into the OTHER side of the story, they only present the one that puts everything into the worst possible light.

    Now I know that isn’t always the case, and it may not be in this situation – but all too often it is. When that is the case, you rarely (if ever) see a retraction of the original story, or even a new story explaining the other side. Its just not sexy enough.

    It’s like all the flak about the Mark 1 containment – but if you read more about it, from the US NRC, and even GE for example, to get both sides, you find out that things aren’t anywhere near what they’re being portrayed to be in the general media.
    The inaccuracy, the misrepresentation, the ambiguous nature, the FUD tactics, all drive me just about crazy.
    MODERATOR
    You just beat me to it:) I was just about to ask you for the link which you have now provided above:)

  115. On the “articles that drive me crazy” post I just did at 11:47 am, I had meant to add in the link to the article. It was from a post by: Shelby, on 25 March 2011 at 10:29 PM

    http://www.bloomberg.com/news/2011-03-25/tsunami-risk-well-known-to-nuclear-engineers-regulators-who-failed-to-act.html

    Oh, and it also said:

    Tokyo Electric Power Co. engineers also did not implement lessons from the 2004 tsunami off Indonesia that swamped a reactor 2,000 kilometers (1,200 miles) away in India, even as they advised the global nuclear industry on how to cope with the dangers.

    So a reactor got swamed from a tsunami that originated far away – again, we would have to know if there was any credible risk to the fukushimi site for something of that nature to occur. Maybe the example they use was a reactor that got swamped by a 0.5m tsunami – if so, how is that relevant to the Fukushimi sites? But do they bother to tell us any of the key facts? NO. What ever happened to the idea that journalists were to answer the 5 W’s (who, what, where, when, why), and present facts in context?

  116. > Rational Debate
    > we would have to know if there was any credible
    > risk to the fukushimi [sic] site … But do they
    > bother to tell us any of the key facts? NO.

    O RLY? read the article. It says in part:

    “… evidence two years ago from geologists that the power station’s stretch of coast was overdue for a giant wave”

    and goes on to give details including

    “sediment samples showed the tsunami had a pattern of recurring every 800 to 1,000 years, according to a 2001 report by a research team funded by the government’s Science Ministry.”

    and that

    “Yukinobu Okamura, who heads the government-funded Active Fault and Earthquake Research Center, asked Tokyo Electric why it hadn’t taken on board evidence of the tsunami risk.”

    Please stop debating. Science bloggers — even many science blog readers — often do check sources. Debating points using claims so easy to refute doesn’t work well in science discussions.

  117. re post by: Hank Roberts, on 26 March 2011 at 1:08 PM:

    Except you haven’t refuted anything I said, Hank. The story never ties the historical evidence to the Fukushimi (or other power station) site, exactly as I already stated.

    As I noted also, the story mentions a single person or group, Okamura etc., without bothering to present the OTHER side of the story – which may well shed an entirely different light on the subject.

    As to checking sources, that is exactly what I expect – and I further expect that not only science types, but hopefully everyone will check not only the original story, but read critically as I’ve noted and then check the other side of the story before jumping to conclusions. All too often that doesn’t appear to be occurring. Journalists ought to be doing that for their readers – but they generally fail miserably on that account whether intentionally or not.

  118. Joffan, on 26 March 2011 at 5:42 AM said:

    The analysis by Gerhard Wotawa written up in the New Scientist is interesting in one respect: the levels of iodine relative to caesium suggest that the reactor cores of units 1, 2 and/or 3 are the source (and pretty much the sole source) of the long-range release – leaving its size to one side for now. Iodine-131 in 5 & 6 and in all the spent fuel pools would be basically non-existent, but caesium-137 would still be present at only slightly-reduced levels compared to the reactor core.

    I agree. It does seem that Wotawa’s study is more interesting at present as which isotopes are seen and not seen in the plume and their relative levels. If there had been large scale oxidation of zirconium cladding in the number 4 spent fuel pool, which I understand contains a full core, offloaded about 100 days ago, then I would expect to see some activated zirconium in the plume. Zr-95 can be produced from Zr-94 by neutron absorption, and Zr-94 is about 17% of natural zirconium. It has a half-life of 64 days and its decay scheme has several characteristic gammas in Nb and Mo.

  119. Pingback: Fukushima Daiichi Nuclear Accident – 26 March status « BraveNewClimate

  120. I also found a DBA scenario for loss of offsite power (LOOP) + guillotine main line break –

    I don’t think there were any large pipe breaks or other leaks, since those would have required raising the alarm with NISA, which didn’t happen until tsunami struck.

    But you’re saying that RCIC requires batteries for the required valves? If so, then I’m still confused because I thought that all three units had batteries?

    There are many possible loads in the battery bus and how long the batteries last depends on which loads are useds, but typical estimates are 6 to 8 hours. When the plant is intact, it’s possible to operate almost all valves (outside of containment) manually, albeit with some difficulty. When conditions detoriorate, it might be impossible to reach such valves because of water leaks, high temperatures or dose rates etc. So when batteries to operate them motor driven or compressors to operate pressurised air valves run out, options become much more limited.

    Let’s say that unit 1 & 2 had already shifted to the lower pressure RHR… both had battery power to run RHR for some time, didn’t they?

    RHR (to be more precise, at least 1 RHR pump, and one service water pump) requires AC power and cannot be run with batteries. In general, there are no electric pumps that run on batteries, batteries are only good for limited amount of instrumentation and control.

    Even if pressure did increase past what RHR could handle, couldn’t they have just switched back to high pressure RCIC?

    You should really look up descriptions of these systems, their interrelations are more complicated than that. RCIC is used for the immediate phase of cooling when the turbine and reactor trips and the condenser and its (seawater in this case) cooling loops are no longer available. RCIC dumps the reactor heat as steam to the pressure suppression pool.

    RHR/LPCI is then used to actually remove heat from containment to outside of the unit with the aid of the “ultimate heat sink”, seawater in this case. RCIC and HPCI cool just the core and dump the heat to the pressure suppression pool, from where it must be eventually removed. In any accident where feedwater pumps and RHR are completely unavailable, the third and last option to cool contaiment is to vent.

    If at some point the RPV pressure had gone above what RCIC/HCPI turbo pumps (using steam turbines) require, that would not have helped to cool the pressure suppression pool, but to heat and drain it further instead. Whether that would have been a good idea at a certain point of time would have depended on the temperatures and pressures of the RPV and PSP as well as the RPV water level.

    Without RHR you essentially have a closed system which is going to keep heating up regardless of how you circulate the water and steam back and forth inside. Which is why they had to vent to reduce the pressure and then introduce outside water source (starting with the unit fire pump) to make up for the boiled water.

  121. @Red_Blue,

    Thanks again for your response and the information. I have been trying to look up information on these systems, that is where the links I posted came from – descriptions of these systems. I’ve had trouble finding much that is more detailed or useful – and am certainly open to any that you or anyone else can provide.

    I understand that RCIC/HCPI only cool the core and eventually the close looped system of water becomes too hot for the cooling to be useful. I thought that I had said that – but I’ve been asking how long they should be expected to be functional BEFORE that occurs, after a scram? Is it really only an hour or two?

    I’d also like to find out information about just what each system can be operated off of (e.g., decay heat steam turbine, diesel, battery), just what their operating parameters are, and that sort of information. If you know of any good information online that way, I’d be most grateful for links.

    Thanks again – I have really appreciated your posts on a number of different subjects and across several threads.

  122. but I’ve been asking how long they should be expected to be functional BEFORE that occurs, after a scram?

    6-8 hours assuming the limiting factor is battery power. If DC power is secured (by aggressive load balancing and by bringing in replacement batteries/DC chargers connected to portable generators), then suppression pool pressure becomes the limiting factor. I haven’t seen any modelling of that exact scenario, but it should not be a difficult calculation. I think you could do a ballpark figure by simply taking the core thermal output curve from decay heat and applying that to the suppression pool volume at normal temperature. I don’t think that time is going to be higher by days though, maybe extending it by 10-15 hours.

    It’s likely though that RCIC/HPCI pump cavitation will start before the suppression pool will rupture, but there are probably significant unknowns in these strengths, because unlike the reactor pressure vessel, I’m not aware of any desctructive “until failure” testing being done to those systems. They have estimated failure pressures that are usually quite conservative, meaning that the actual failure could occur at much higher than anticipated pressure, but will not occur before that. Then there are also large safety margings between that and the “design pressure”.

    There is suspicion that the suppression pool of unit 2 suffered a leak, but there is no confirmation or information how it happened or how serious it is.

  123. @Rational Debate 4:36PM

    I hesitate to put out this calculation in the presence of the experts here. But perhaps they will correct my numbers and give the answer you’re looking for.
    Please feel free. This is a semi-informed, back of the envelope calculation.

    My understanding of the turbine driven emergency cooling is that it uses the high pressure steam from the reactor to drive a turbine driven pump to provide pressure for coolant circulation. The exhaust from that turbine is vented into the suppression pool. Such a closed system will heat the suppression pool whose pressure will rise until no more steam can be exhausted into it and the turbine will stop.

    From this reference:

    http://library.thinkquest.org/25916/database/newyork.htm

    I got that the minimum volume of the suppression pool was 105600 ft^3 and the condensate tank 400000 gal for a total of 4504m^3. If it starts at 20C and heats to 100C with a specific heat of 1cal/gm, it will absorb 1.509*10^12joule.
    From this reference:

    http://lpsc.in2p3.fr/gpr/PPNPport/node56.html

    The 1GW reactor is making somewhere between 200MW and 16MW in the period between the scram and 1 day after.
    I gave it 40MW just to have a number in there.
    40MW goes into 1.509*10^12joule 37720sec or 0.437 day.
    Given my expertise in this field, this is pretty much just a numberized WAG but there you have it.
    Corrections are welcomed.

  124. Has anybody considered using a big thermoelectric generator to run cooling pumps? The efficency is pretty dismal, but in this circumstance I don’t see that as an issue. The advantage is having no fluid conducting openings to the heat source, just wires. Now your heat exhaust (cold junction) can be the ocean directly.

  125. At the very beginning of this event i realised something that i saw as very good. Under the circumstances it seemed ill advised to comment this, but now it may be a better time. The good thing is that in all of 40 years the Japanese did not get sloppy on safety. I even recall an article on Tepco adressing its workforce on awareness for the dangers of getting sloppy. 

    To my understanding there is nothing ‘offcourse’ about this. During the fall of the Soviet Union the Bulgarians had quite some difficulty in maintaining safety standards, relying to some extend on volunteers to keep their plants running. I recall seeing a German tv documentary on this subject only. Never the less the event in Fukushima proves guaranteing safety level maintenance over decades is evidently realistic, which is (my opinion) a good thing.

    Another thing the Fukushima event proved is the usefullness of extradiciplinary technology. It has been stated before: the presence of very little relatively cheap equipment would have made a big difference here. A difference in attitude or approach of the safety ussue may prove very productive. The box didn’t hold so lets think beyond it. If hammer-and-plyers-technology saves the day, it might be wise to invite it to stay.

    A third point is the damage assesment. Nuclear science has the tendency to walk away from responsability for effects such as global panic or at least not see this as ‘their’ part of the damage. I consider this not only unrealistic, but also inproductive. A sound clear and conclusive public information policy greatly reduces this damage. I see myself sharing a problem with the pro-nuclear society there. Lack of competence in conclusive communication. To my knowledge adressing this problem reduces actual damage way faster than any on site safety measure. The answer to the question if this event is a victory or a defeat for nuclear energy relies almost entirely on the way it is presented to the public. Thank you.

  126. Ernie Hamilton, on 26 March 2011 at 9:43 AM said:

    In one of the threads there was mention that the Brown’s Ferry secondary containment vessel could not hold pressure at 70 psi (~4.5 atm) when they tried to pressure test it during construction.

    I posted a seconday source for this a couple of times in the last week or so. You will find it at the following site with a lot of other information on for example the SFPs.

    http://allthingsnuclear.org/page/2

    Go down to “How Hydrogen May Have Gotten from Primary Containment into the Reactor Building”

  127. Red_Blue wrote:

    deliberate attempt to reduce activity release by venting to the secondary containment instead, perhaps hoping that SGTS could be restored before reaching explosive concentration

    Thanks for your reply. Do you have any knowledge of a venting pathway that would lead from the primary containment vessel and intentionally to the secondary containment structure? You are assuming this is possible to do (but I haven’t seen any indication that this is the case from reactor plans or second hand commentary). Why would you engineer a pathway to intentionally flood a primary working area of the building with dangerous radioactivity and gases from the primary core containment structure. You are suggesting this is done to diffuse the gas so it can be taken up by the standby gas treatment system, but this area is not kept free of oxygen with inert gas, and the hard vent was installed exactly for the function you describe (and without the consequence of damaging the reactor building and rendering one room of the site permanently uninhabitable)? If this is an option, how can this be done from the control room.

  128. On another blog it has been suggested to change the cooling agent for the pool from water to air all together in emergency situations. Some drawings published indicate that above the pool there is free space up to the roof unless the crane is there. A fall-in-place chimney above the pool was suggested. If the water level reaches the cores, the pool is shock drained allowing large amounts of air to flow in at the bottom. It would not keep all radioactivity inside, but allow less to escape than in the current situation. According to some argument on this blog, the draft would be powerfull enough to keep the cladding from melting or interacting with steam and its passive, thus ruling out the need for outside power to keep it stable. Another advantage would be the escape from polluting the pool with seawater. Closing the bottom while shock filling the pool might put it right back in business. I have no means to do the math on this option, but it does not sound entirely impossible to me.

  129. According to “rational”

    ” they’ll sue a driver for merely tossing a bit of trash out the window”

    Is this typical or extreme?

    Why use extreme instances to consider mainstream issues?

    What is your evidence?

  130. re post by: Mike, on 27 March 2011 at 10:16 AM said:

    Mike, I’m sorry, but i have no idea what you are trying to get at. Also, note that my post said In general people aren’t unreasonably afraid of cars such that they’ll sue a driver for merely tossing a bit of trash out the window. So its not a good analogy. Basically the opposite of in meaning than if one only reads or considers the part of my sentence that you extracted….

  131. @Red_Blue and DrD re the RCIC system parameters.

    Thank you both for your posts. DrD, I’ll have to look at the links you provided.

    If we assume battery isn’t the limiting factor because they’re available etc, then I thought that the next limiting factor to the system was temperature thoughout the water volume, not just in the suppression pool or torus, but all -e.g., suppression pool + torus + RPV…. and that it was only useful until the total volume of water in the loop was too hot to successfully cool the core?

    It is, afterall a loop – the steam line runs thru turbine and dumps into the suppression pool, but that turbine drives the RCIC pump, which pulls water from both condensate tank and suppression pool, routing it right back into the RPV….

    Red_Blue, I could also see how in that system if the pressure capability of the pool would/could come into play, but wouldn’t steam just be blown off/vented sufficient to keep that from being the limiting factor?

  132. @Rational Debate: Remember, the whole plant was flooded with electrically conductive seawater when the tsunami hit. Who knows what systems were shorted out when that happened. The batteries may be designed to run for 6-8 hours, but if circuitry they’re hooked up to got shorted by seawater, they could easily have been drained MUCH quicker than that.

  133. @Milamber33
    Some loss of battery power due to seawater short circuit must have taken place, assuming they were exposed at all. The extend varies enormously depending on the construction of the batteries themselves. My experience is that they are to quite some extend protected against it. At Tudor we covered the cell connectors with hard fat for that reason. It all depends on how much and for how long conducting surface was exposed and that varies from insignificant to conclusive. Again, it is custom to construct emergency backup systems to be able to survive the circumstances in which they may be needed.

  134. @Milamber33
    The forementioned meaning a sensably designed emergency battery pack or cell array should be able to hold on to its capacity and remain operational, even after being fully immersed in sea water. Thus supporting Rational Debate’s assumption. Whether the rest of the circuitry does that too may be unsure, but that does not significantly influence the batteries capacity.

  135. @bchtd1parrot: Fair point, but I was more talking about the seawater getting to things like pumps and valves the batteries were connected to, rather than to the batteries themselves. I was kind of assuming that if seawater got to the batteries themselves and they didn’t have any protection they’d be dead almost instantly.

  136. Seawater getting to the batteries themselves is very unlikely capable to cause immidiate servere damage. You must understand the short circuit in that case is due to electrolytic process, not conduction like with metal. Pure water does not or hardly conduct at all. Its the salt that does the trick. Thats why the connecting surface matters and because it does, battery array manufacturers tend to close that up by sealing as much of it as possible. We used warm fat brushed or sprayed on the connectors after welding and then briefly melt it with a torch.

  137. Again, my main point was that any shorts in the rest of the circuit would decrease battery life, possibly quite significantly. Of course the batteries, if they’re closed units, would survive so long as no seawater got into their casings.

  138. @moderator
    If this is another feature of the ipad format it should be over some time monday.
    (source WordPress.support).
    Following this post is doable, the open post takes 4000+ swipes per hour.
    (ipad has no scroll besides swipe)
    MODERATOR
    It’s a WordPress thing, totally out of our hands.

  139. 3d attempt

    @Milamber33
    The low voltage power part of the system is hardly influenced by sea water. That’s why its possible to weld under water. It would stricktly speaking be possible to imagine a construct that would drain the batteries, but nothing sudden and its still a bit of a 6er in the Lotto. Assuming the battery capacity was not significantly influenced by the sea water, either direct or indirect, is the statisticly more likely variant.

  140. Dr. Hannum wrote:

    This was not a disaster (the earthquake and tsunami were disasters).  This was not an accident; the plant experienced a natural event (“Act of God” in insurance parlance) far beyond what it was designed for.

    I’d like to suggest we need to update and correct this statement as well. I think we have increasing evidence that this was a design based accident (and not a natural one): poor planning over an extended period of time for tsunami and earthquake site characteristics, poor primary containment design (we appear to have several breaches, spilled water, and pipe breaks throughout the site), inadequate containment for spent fuels (with water as the only primary containment barrier), inadequate evacuation and accident response plans (WSJ suggests they delayed cooling efforts during initial 24 hours with seawater at crucial initial phases of response), and more. We can definitely do better, and we no longer have to repeat the mistakes of 40 years ago to make nuclear power continue to be safe and reliable in the present.

    Appearing in the Times yesterday, the verdict appears to be in on the question of tsunami planning and preparedness. Government guidelines overlooked the issue in 2006 (despite nonbonding recommendations in 2002, and additional warnings two years ago). Challenged with public and regulatory scrutiny after 1995 Kobe and 2007 Kashiwazaki earthquakes, still few changes (and nothing on tsunamis). A nuclear engineer working for Hitachi for 40 years described the safety and risk assessment culture this way: “Japanese safety rules are deterministic because probabilistic methods are too difficult … the US has a lot more risk assessment methods.” Tsunami and earthquake experts in hindsight described the many oversights this way: “a cascade of stupid errors that led to the disaster” (and more of the same from these experts over here). And this account from a Toshiba engineer on the early planning for the Fukushima plants (and safety culture in Japan): “We didn’t take a tsunami into account.” And a 10 year plant extension (received one month before accident) failed to take seriously these and other many concerns. I think I risk stating the obvious, but the more we learn about this design based accident, the more we learn about the many ways it could have been prevented.

  141. Pingback: The Real Disaster in Japan is the Earthquake « French News Online Blog

  142. I think the close proximity of reactors does hamper operations too… perhaps a wider distribution of reactor buildings must be enforced in the future. The radiation of neighboring buildings *should* be of lesser concern to workers when trying to cool some unit manually (or working on it otherwise).

  143. Units 5 and 6 are not right beside Units 1-4. That has removed radiation from Units 1-4 as a serious concern. There has been speculation that the hydrogen explosion at Unit 4 came from hydrogen generated at Unit 3, through the common vent stack or some other route. Not likely in my estimation, but if it proves true that would be another indication that reactors should not be built too close together.

    There is also the consideration ot siting of multiple units on one ste, with the possibility of a common source of multiply failure, as in this case. Now it has been found that multiply reactors on one site helps to quickly disperse information amoung operators of leasons learned at the other reactors. There is a study of CANDU reactors in Ontario that shows that. I read about it many years ago so do not have a link. So that is a plus of having many reactors on one site.

  144. Factual errors in the article:

    “After the normal feed water supplies were exhausted, they activated the system to supply sea water to the core, knowing this would render the plant unfit to return to operation.”

    Wrong. There is/was no system in place to supply seawater. This was improvised using mobile pumps and fire hoses.

    “Since this is a Boiling Water Reactor (BWR), it is good at boiling water. Operating with the water level 1.7 to 2 meters below the top of the core, they mimicked power operation; the core normally operates at power with the water level well below the top of the core, the top part being cooled by steam.”

    Wrong. Even in a BWR the entire core must be below the water surface at all times.

    I kind of lose interest in the article when it gets simple facts like these wrong.
    MODERATOR
    You are breaking the BNC moderating rules here(please check these on the About page) by not supplying references to support your contentions. Further comments without these links will be deleted and you will be asked to re-post.

  145. Pingback: The Real Disaster in Japan is the Earthquake | FrenchNewsOnline

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