The crisis at the Fukushima Daiichi nuclear power station has been unfolding for about a week. The on-site situation remains extremely serious, with glimmers of hope being shrouded by a shadow of deep uncertainty.

A Japanese dog gets scanned after possible radiation exposure. Photo: AP

If you’ve not been following the situation on BraveNewClimate, please visit the site, which contains assumed knowledge for understanding the rest of this post.

As predicted, attention over the last couple of days has focused on the critical situation with the ponds used for temporary storage of spent nuclear fuel at the individual reactor units, before it is moved to a centralised facility on site. Although this old fuel has lost much of its original radioactivity, the decline is exponential, which means that thermal energy must continue to be dissipated for months.

Again, see this page for specific technical information and diagrams.

Nothing can be confirmed at this stage. As has been the case throughout this crisis, information is hard to come by and must be pieced together.

Are the spent fuel in the pools in Units 3 and 4 are now uncovered? TEPCO claims that NRC Chief Jaczko was wrong in claiming this, that the spent fuel pools in both Units 3 and 4 need some refilling but are NOT dry. (The Japanese authorities are apparently saying they’ve seen water still in the Unit 4 pool.) The big concern here is that unlike the releases from damaged fuel in the reactor cores of Units 1, 2, and 3, which were largely filtered by scrubbing in the containment suppression pools (wetwell torus), releases of volatile fission products (e.g., cesium and iodine) from these spent fuel pools have direct pathways to the environment, if they remain dry for an extended period.

Efforts to deliver water to these pools have proven to be very difficult, and fuel damage may be occurring.  If they are exposed, then the use of the evaporation of salt water as a heat sink over periods of more than a few days is not viable because the quantities of salt deposited as the water evaporates becomes large in volume and plugs the flow paths through the fuel, degrading heat removal. Everything that is cooled becomes a heat sink to condense anything volatilised. Unfortunately, a fresh water supply seems difficult to come by.

One option is to bring fresh water by helicopter, but the amounts needed imply a large number of flights and gamma radiation levels are high above the pools making overflights hazardous. NHK reported a number of successful water dumps using helicopters yesterday. If radiation levels on the ground increase further, personnel access will become more challenging. Additional spent fuel is stored in pools in Units 5 and 6 and in a large centralized storage pool. A key issue is how to continue to make up water to these pools in the longer term, particularly if site access becomes more difficult.

It was announced at a press conference that a total of 11 specially-equipped vehicles will be used to spray water on the crippled reactors at Fukushima-1 after an access path is cleared using bulldozers. The big advantages of fire trucks over helicopters is that their water cannons can be better aimed, from the side rather than the top, and their operation is continuous rather than in batches so they can deliver vastly more water. It is clearly an appealing option. An additional 130 personnel have also been moved back on site to help with work.

Based on the information coming out of TEPCO, it appears that units 1,2 and 3 remain critical but stable. Partial melting has almost certainly occurred in all three cores. There was definitely a period of no water injection because of a pressure buildup caused by stuck relief valve — always a potential issue for in high pressure systems.

In summary, this accident is now significantly more severe than Three Mile Island in 1979. 

It resulted from a unique combination of failures to plant systems caused by the tsunami, and the broad destruction of infrastructure for water and electricity supply which would normally be reestablished within a day or two following a reactor accident.

My initial estimates of the extent of the problem, on March 12, did not anticipate the cascading problems that arose from the extended loss of externally sourced AC power to the site, and my prediction that ‘there is no credible risk of a serious accident‘ has been proven quite wrong as a result.

It remains to be seen whether my forecast on the possibility of containment breaches and the very low level of danger to the public as a result of this tragic chain of circumstances will be proven correct.

For the sake of the people there, I sure hope it does stand the test of time.

This is an edited extract from Barry Brook’s website, BraveNewWorld.

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29 comments

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    • Erick says:

      04:47am | 18/03/11

      Thank you for this article. It’s good to see a rational, fact-based analysis without hysterics.

    • Adam Diver says:

      07:18am | 18/03/11

      He even admitted he made a wrong hypothesis, I didn’t know such things occurred these days.

      Excellent article, it seems that every concievable disaster or issue, has occured on this one plant. Hopefully it remains intact.

    • Rick says:

      03:59pm | 18/03/11

      Unfortunately the poor poeple trapped in the rubble around the plant that didn’t get rescude because fo the exlution zone wouldn’t give a damm about your rational,factbase analysis.

    • acotrel says:

      08:44pm | 18/03/11

      What is really unpleasant was expressed by an ex-pat Assie who fled from Japan!  He lacked confidence in the Japanese ‘experts’ because of their body language!

    • acotrel says:

      06:38am | 19/03/11

      @Adam Diver
      ’ it seems that every concievable disaster or issue, has occured on this one plant’

      In your own words, everything which has happened was ‘conceivable’!  THEREFORE PREDICTABLE!!  What happened when the risk assessments were performed prior to the plant being built?  I wonder who was told to shut up?

    • CJ Morgan says:

      07:18am | 18/03/11

      Thanks for this, Prof Brook.  Your factual and dispassionate analysis is a welcome change from some of the hysterical nonsense pervading the media about Fukushima.

      However, even you would have to acknowledge that the adoption of nuclear energy in Australia will be a political impossibility for the forseeable future.

    • Elphaba says:

      08:46am | 18/03/11

      Unfortunately, yes, this has killed the nuclear debate for some time.

      I have found that attempts to direct people to statistics showing how many people are killed by coal every year, and the amount of radioactive waste is pumped in the air from burning it, has been met with stonewalling, emotive outbursts, and name-calling.

      You can’t help the ignorant.  You can only hope they don’t procreate, or get a job in TV.

    • fairsfair says:

      10:59am | 18/03/11

      Agreed.

      On lateline last night Tony Jones was doing his bestest to get the English expert he was talking to cough up some info on plumes of radioactive dust coming from the reactor. He all but quashed it, but good old Tony finished it off with some comment about “...radioactive isotopes spewing into the air and we are out of time”.

      Meanwhile, that picture of that dog reminds me of Kim Phuc after her village was attacked with Napalm….

    • acotrel says:

      06:49am | 19/03/11

      @Elphaba Yes there is radiation released from coal burning.  Yes there is radon released from the bricks in the walls of houses. Yes there is radiation exposure caused by power lines.  Yes mobile phones give off radiation.  Yes electric blankets give off radiation.  Yes smoke alarms give off radiation.  NONE of that mitigates the risk when a nuclear facility goes critical ! The argument that we should move towards nuclear power stations because of CO2 release from coal fired facilities is ansurd!  It replaces a medium level risk, with a high level risk! It’s like the monkey bashing the typrwriter,if he does it long enough eventually he must end up typing Shakespeare !

    • JIm says:

      05:48pm | 19/03/11

      No wonder you’re a failed safety advisor acotrel…nuclear = extremely low probability, high consequence. Coal = high probability, high consequence.

      Live next to a coal station you’re guaranteed to get sick.

    • Daniel says:

      07:23am | 18/03/11

      I think this is another Chernobyl. The authorities kept all that very quiet too.

    • iansand says:

      08:21am | 18/03/11

      Why do you think that?  What source?  What qualifications do you have to carry out an analysis on what facts?

    • marley says:

      08:29am | 18/03/11

      No.  We have known since day 1 that there was a problem at Fukishima, everyone’s watching, there are IAEA experts and other international experts on the ground.  No one knew about Chernobyl until the radiation hit Sweden.  The Soviets refused to provide information, and basically it had to almost be forced out of them.  The Japanese are being far more forthcoming.

    • Ryan says:

      09:14am | 18/03/11

      @Daniel: you really shouldn’t believe everything in the media mate.

    • Andy says:

      09:14am | 18/03/11

      This is exactly the kind of ill-informed hysteria this article tries to fight against.

      Chernobyl had a completely exposed reactor core in full meltdown on fire for 10 days and civilians were not evacuated until the 4th day.

      Fukishima is designed so even in the event of a full meltdown the reactor core cannot be fully exposed. Nuclear scientists are not so stupid that they have learned nothing since the 1980s.

      Even if the worst case scenario was realised and there was a full meltdown of the reactor cores it would not even be close to Chernobyl.

    • Ignorant comment says:

      09:17am | 18/03/11

      It’s worse than Chernobyl. It’s only a matter of time before those reactors go critical and wipe half of Japan off the map. The radiation cloud will then head to Australia and kill hundreds of thousands of people.

    • Rev says:

      10:46am | 18/03/11

      C’mon everybody - don’t feed the trolls.

    • Gregg says:

      11:26am | 18/03/11

      @ Andy,
      Perhaps a difference in design but with all nuclear fuel reactors they are designed tio contain radiation.
      ” Fukishima is designed so even in the event of a full meltdown the reactor core cannot be fully exposed. Nuclear scientists are not so stupid that they have learned nothing since the 1980s.

      Even if the worst case scenario was realised and there was a full meltdown of the reactor cores it would not even be close to Chernobyl “

      Fukushima is some 40 years old which means commissioning about 1970 with design and construction in 60s, Chernobyl being in 1986.

      If you have a full meltdown, what kind of heat/pressure do you reckon will be occurring in the reactor chamber?
      Boom! and no different to Chernobyl if that occurs.

      With what we do not know about what’s going on from external observations as the article author reports the authorities saying, we have a real Rumsfeld scenario -  ” we do not know about that which we do not know of ”

    • Tim says:

      01:25pm | 18/03/11

      Gregg,
      Chernobyl was caused by a graphite fire in the fuel when the reactor was running at full power. Fukushima has no graphite in the reactor and is not currently running.
      Chernobyl had no containment at all, Fukushima has two levels (possibly compromised).

      Even if worse comes to worse, which is unlikely, the result will not be anywhere near the level that Chernobyl was.

    • Gregg says:

      02:56pm | 18/03/11

      @Tim,
      Well not quite as you state it Tim for the fire came after the explosion and the explosion occurred because of a test that became uncontrolled and the explosion blew out the chamber as well as the outer containment.

      I doubt you will find any nuclear reactor not in a reaction chamber and I certainly would not be travelling anywhere near one.
      You can read details on Chernobyl @ http://www.rri.kyoto-u.ac.jp/NSRG/reports/kr79/kr79pdf/Malko1.pdf
      Still quite a few safely operating or lets hope they are safely and maybe they have been modified to make an occurence like at Chernobyl less likely.

      The design of the Japanese reactors may be inherently safer from what is claimed but it is using enriched uranium as against the lower grade at Chernobyl and despite all that inherent safety, they’re not applying as much cooling water as possible for no good reason, you still having a heat producing nuclear fuel reaction situation.

      Despite the design differences, there is still a reaction chamber and outer containment, not much of the latter existing because of the pressure bleed off from the reaction chamber necessary.
      If something goes wrong, and there are some indications of a partial melt down, do we know that the reaction chamber will remain stable?
      A reasonable description/comparison @ http://www.newscientist.com/article/dn20257-why-fukushima-daiichi-wont-be-another-chernobyl.html

    • marley says:

      07:36pm | 19/03/11

      Sorry Gregg, but you’re wrong. Chernobyl had no containment chamber.  When the pressure vessel blew, that was pretty much it.

    • Troy says:

      08:13am | 18/03/11

      What is all this rubbish about “hysterics”?  Frankly, I think both the popular press and commentators have pretty much low-balled the reality of the situation.  In fact, I think it is the pro-Nuke camp that has shown the real “hysterics”, what with their “nothing to see here” PR campaign that got trotted out almost immediately after the event precipated.  All of them, of course, blaming the “environmentalists”, as if they had anything to do with the situation at all.  One writer even suggested they would be “high fiving” each other over it.  Yes, that makes sense, people who are opposed to something because they think it is dangerous “high fiving” each other when it proves to be so.  “I told Johnny to wear his seat belt.  Now he didn’t and he’s dead.  High five!”

    • Mattb says:

      04:16pm | 19/03/11

      Have to agree with you Troy, Ziggy’s ‘nothing to see here’ punch article was nothing more than a disgrace, the situation wasn’t even three days old when he blessed us with his ‘un-bias’ opinion.

      The you had the old comparison argument that goes ‘people die in car crashes, plane crashes etc etc, but we don’t stop driving or flying’. Yeah right, so a car crash and a disaster involving a nuclear power plant are the same thing and have the same consequences, whod’vethunk eh.

    • Ringo says:

      08:49am | 18/03/11

      The DFAT sends me an email:

      “For those Australians in Japan but outside the affected areas, based on current information, ARPANSA advises that they are extremely unlikely to be contaminated and the health risks are negligible.

      Given the very low risk of exposure, ARPANSA advises that people should have no physical symptoms. If there is any doubt about contamination this contamination is easily removed by washing your body and clothes.”

      At the exact same time the News Ltd headlines read:

      “Radioactive cloud spreads over Japan.” (not an exact quote, but ‘radioactive cloud’ was the image they chose to use)

      You really think the popular media have been underestimating the level of threat?

    • Troy says:

      10:09am | 18/03/11

      “outside the affected areas”. 

      What is that, exactly?  30kms?  80kms?  Or does it depend on which way the wind blows?  Or is the reader supposed to figure that out himself?  Great way to dodge responsibility that.

    • Ringo says:

      11:38am | 18/03/11

      The entire travel advice is much longer than that excerpt of course.  The area considered outside the affected zone has been specified each update, as has the impact that changing wind conditions could have for people outside of the exclusion zone.

      So why do you think the DFAT are trying to dodge responsibility?  They have no interest in saving face for TEPCO.  What basis do you have for questioning the motives of their travel advice bulletins?  They have access to good information channels, and their safety advice tends to fall on the precautionary side.  Why would they be telling travellers that they have negligible risk of contamination outside of the exclusion zone if they didn’t believe it, or didn’t know?

    • stephen says:

      06:45pm | 18/03/11

      (From my latest info., it’s pot no.3 which is in danger of meltdown.)
      And this is from a country that built a Nuclear Power Station along geographical fault-lines in the path of a possible tsunami and without a even a disaster back-up program for emergencies.
      Prime Minister Gillard should change her mind on Nuclear Power for this country. We do need it, and Japan’s difficulties would not be ours.

    • MK says:

      12:16pm | 19/03/11

      Damn it Barry
      with all those clear level headed observations
      you forget a critical peice of information…

      Is the dog Okay?Let us salute this brave pooch who is obviously putting on a brave and happy face and staying strong,
      depseite the impending nuclear armageddon

    • Dan Cass says:

      09:33pm | 19/03/11

      C’mon nuke boys.

      Nuclear power was never going to power the world and its public enemy number one now.

      Stop wasting time on a dead issue and be constructive - support renewables and save the climate.

 

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