Read this post in Japanese and German.
Dear Akio Matsumura,
I write in response to your blog post of 11 June 2012, titled “What is the United States Government Waiting for?” Your post addressed the radiological risk currently associated with the Fukushima Dai-ichi nuclear generating station in Japan, especially the risk associated with the spent-fuel pool at Unit 4.
Your concern is appropriate. The radiological risk at Unit 4 will remain high until all spent fuel in that pool has been removed and transferred to dry storage. Options are available for reducing the risk in the interim period until transfer of spent fuel to dry storage has been accomplished. Please note, however, that risk is not unique to the Unit 4 spent-fuel pool. Various risks are associated with the nuclear-energy sector in Japan, and options are available to reduce those risks.
You have called for an independent assessment of risks and risk-reduction options at the Fukushima Dai-ichi station. Such an assessment, if properly conducted, could be very useful. Experience suggests that major Japanese institutions, in industry and government, may not be fully aware of the risks and the risk-reduction options.
At various times and places, there have been independent assessments of risks and risk-reduction options associated with the nuclear-energy sector. An example is the Gorleben International Review of 1978-1979. I had the privilege of participating in that Review as one of 20 international scientists. The Review was commissioned by the government of the state of Lower Saxony, in what was then West Germany, to examine a proposal to construct a nuclear fuel center at Gorleben. Findings of the Review addressed radiological risk and other matters. The Review had a substantial effect on nuclear-energy policy in Germany.
You have suggested that the US government could assess risks and risk-reduction options at the Fukushima Dai-ichi station. I regret to say that the US government is unlikely to provide a truly independent assessment. Some arms of the US government, such as the national laboratories, have the technical expertise that is required. However, the US government would probably assign a lead role to the US Nuclear Regulatory Commission, which has a poor record of understanding, and acting upon, the risk posed by storage of spent fuel in pools.
Japan could conduct its own independent assessment of risk and risk-reduction options. Such an assessment could be commissioned by a municipal or prefectural government, or by a private body. The assessment should involve international experts and experts from Japan. It is important to note that there are many capable experts in Japan. The nuclear-related institutions in Japan are deficient in various respects, but there is no lack of capability and objectivity at the individual level.
With best regards,
Gordon Thompson
Gordon Thompson is executive director of the Institute for Resource and Security Studies (Cambridge, Massachusetts), and a senior research scientist at the George Perkins Marsh Institute, Clark University (Worcester, Massachusetts).
I would be surprised if TEPCO have not done this already. Some sort of deterministic or probabilistic risk assessment is a normal part of the safety case process for a nuclear or radiological facility.
What is most likely needed is an organisation or person with the expertise to independantly verify such an assessment.
The US DOE have carried out assessments of the release fraction of nuclides from spent UO2 fuel heated to different temperatures. So the consequence side of the problem can be worked out as follows:
1. Calculate the decay heat level of each rod, given its burn-up and age;
2. Calculate the equilibrium temperature of each rod in still, dry air;
3. Calculate the ceasium inventory of each rod, based upon burn-up and decay during residency;
4. Use the DOE results to calculate the release fraction of each rod at its equilibrium temperature;
5. Use an atmospheric dispersal model to estimate the radiological consequences.
The other side of the equation is frequency of release, or probability per year. What is the probability of failing to keep the pond covered? This might be calculated as being the probability of pump failure, multiplied by the probability that the fault will not be detected and repaired in time.
The next step: using safety class analysis, how many other diverse and redundant safety measures are needed to reduce the risk to a tolerable level? These measures might be: redundant pumps, power supplies, operator actions, etc.
In light of the election result especially, Japan is now at a crossroads that could determine its future to an equal or greater extent than December 7 1941. On that date Japan, despite its undoubted technical brilliance and social cohesion, after a long period of descent into political extremism and strategic folly, crossed the point of no return into disaster that almost destroyed it, and cost it its Empire, and much of its wealth and position in the world, as well as millions of lives. It did so lulled into a false sense of overconfidence and security, partly by the world situation, and actions of others, but decisively by its own at the time excessive arrogance and shortsightedness, combined with a social-political conformity that whilst a great strength in normal times and constructively applied, can become a possibly fatal liability in circumstances of exceptional risk and crisis. Now is one such time. Japan faces an extreme risk of national disaster by the fragile situation at Fukushima, which one more large quake could turn into a major nuclear catastrophe beyond anything yet seen, and which could be destructive on a global scale. The amount of toxic radioactive isotopes that could be released if the fuel assemblies are exposed in the event of cooling failure due to another possible even likely large seismic disturbance are by all credible accounts enough to render much of Japan uninhabitable for centuries at least, as well as poison tens of millions of people within and beyond Japan. It must be the no. 1 priority of the new government to take all possible prudent action to reduce and eliminate this threat as urgently as practicable, every day lost could be the last. It has been quoted in the media that there are plans to remove the fuel assemblies by 2014, this is at least one year too late, it should already have been done. And furthermore, Japan’s nuclear industry must be upgraded and rendered safe such that another such disaster is not merely unlikely, but impossible. It was thought such a disaster would not occur, but it did. That means it can certainly happen again. The reactor design was and remains a poor one with enormous safety liabilities, an urgent priority should be to a) shut down any plants that are at serious (ie similar) risk of natural disaster, b) render fuel assemblies safe and adequately dispersed to prevent the possibility of another such disaster, and c) introduce new and safer plant designs. An overall threat assessment in light of the unforeseen events and revised contingency planning would also be in order. The new government must not go back to ‘business as usual’, for that would clearly and forseeably be to risk a repeat on an even more devastating scale.
JAPAN WAKE UP NOW TO THE MASSIVE RISK OF RENEWED AND EVEN NATIONALLY FATAL DISASTER!
JAPANESE LEADERS AND PEOPLE TAKE ESSENTIAL PREVENTIVE ACTION NOW WHILE THERE IS TIME!
DO NOT LET PETTY CONSIDERATIONS OF ANY SORT OBSTRUCT VITAL ACTION!
JAPAN IS AT THE CROSSROADS AGAIN, THIS TIME CHOOSE THE RIGHT AND SOUND COURSE!
DO NOT LET THIS GOVERNMENT GO DOWN IN HISTORY AS JAPAN’S LAST AND MOST RECKLESS!