Mister Okada, after the reactor catastrophe in Fukushima on March 11, the public opinion in Europe at first was that the natural catastrophe with an earthquake of highest intensity and a Tsunami of average 14m height was so enormous, that one could not blame anyone.
A report of the European association of power and heat supply (www.vgb.org) mentioned, however, that Fukushima Daiichi was designed for a Tsunami-height of only 5.7m, although a Tsunami of height more than 10m has to be expected every 30 years; and that practically all damages at Fukushima Daiichi were caused by the Tsunami.
Can you confirm this observation? If yes, what are the reasons for having ignored this data base? And if not, what is your view of the accident scenario (catastrophe versus power plant dimensioning)?
Dr. Okada: There are several theories regarding earthquakes and I am not sure whether the theory that a Tsunami of a height of more than 10m has to be expected every 30 years is reliable. However, it is true that it has been pointed out that the Jogan earthquake which occurred in 869 and the following Tsunami should be taken into account to estimate the level of the potential Fukushima Offshore Earthquake. The level of the Tsunami induced by the Jogan earthquake is said to have been larger than the Sioyazakioki Earthquake in 1938, which served as a basis for the design of Fukushima Daiichi. It is possible that the Jogan earthquake was not considered as it is recorded in very ancient documents.
What is your evaluation of the accident management directly after the Tsunami (cooling with seawater, assignment of the Tepco-workers on site, blinding of the soil, communication with and evacuation of the residents)?
First of all, in my opinion, cooling reactors using seawater was inevitable as emergency measure in the situation where there was not enough fresh water, since cooling reactors continuously is top priority. Therefore, the judgment of the director of the Fukushima Daiichi Nuclear Power Station to continue injecting seawater in spite of the direction from the TEPCO headquarters was right. It should be left out of consideration to stop cooling which was once started, even though the possibility of re-criticality could not be ruled out.
I do not have detailed information on the immediate reaction of TEPCO-workers after the accident. However, putting aside the reaction of the TEPCO headquarters, the employees of TEPCO on the site and the workers of the contractors who remained on the site and kept working without taking time to rest or sleep in the fearful and tense situation were laudable. A female TEPCO employee who was ordered by her boss to evacuate as the legal exposure limit is set low for women wrote on her blog that she wanted to remain on the site to work with her co-workers. I was deeply touched when I read it.
Regarding the blinding of the contaminated soil around the site, there are two aspects. The merit is to prevent contamination from spreading to the surrounding area and the demerit is to worsen the working environment by localizing contamination. Also, as to covering with polymer material, there was concern about the risk of radiation deterioration. Irradiation test of the material conducted at JAEA demonstrated that it changes to gel-like material, which could cause problems such as clogging of pumps. In fact, this material was not poured in the buildings containing pools. Further review is necessary to make judgment on the pros and cons of covering with polymer material.
In my opinion, the setting of evacuation areas just after the occurrence of the accident was appropriate.
What is your evaluation of the further steps taken (up to today)? For instance, how do you assess the official communication on level of the residents, the nation and also internationally? What do the people involved want to know, what do they have to be informed about?
Many people have a suspicion that “the government and TEPCO might hide some important information”. In reality, on the contrary, a flood of information is provided. Both the government and TEPCO submitted bulky reports and relating administrative institutes post renewed information on their websites every day. However, it is doubtful that even experts have read through all those thick reports, as organizing the information submitted separately by each administrative institute takes a lot of effort.
Additionally, scholars and commentators appearing on the media express diverse views. In general, hundred scientists tell hundred stories. As a result, people get confused about which opinion they should rely on.
In such a situation, people want “a simple explanation”. Accordingly, the announcements from the government tend to be focused on the conclusion “There is no imminent danger”. There is a wide gap between a flood of information and short announcements by the government.
Recently, there has been a movement among people to buy instruments to measure radiation to protect their health by themselves. As this movement shows, what they want to know is the “facts”, that is to say, the current and accumulated values of radiation and radioactivity, and the “basis” to decide whether such values are safe or not.
Also, the means to provide information need to be decided carefully. Posting information on internet websites is not enough, since still a significant number of people do not use internet. Therefore, how to convey information is important as much as what information to convey. It is desirable to disclose through the media unified and comprehensibly organized information that shows “facts” and “basis”.
How do you assess the current state of the damaged reactors, the environment, the radiation and radioactivity of air, soil, water and food?
I think that we have got out of critical condition in regard to the accident. However, the condition can be said under control only after the cold shutdown with stable operation of circulating system of cooling water is realized, and it has not yet been achieved. We are currently at a stage where efforts are being made toward cold shutdown. As to the state of the damaged reactors, I do not have any more detailed information than the information TEPCO released.
The values of environmental radiation and radioactive have lowered. However, the contamination of the soil has not died down due to radioactive caesium which has long half-life. The soil must be restored. A similar cause is also behind the cows contaminated by consuming straw.
What can actually already be said today about lessons learned, and what will not be possible to evaluate until the coming years, maybe not until the next generation?
In general, the expression “beyond anticipation” should not be used for the accident at Fukushima Daiichi Nuclear Power Station. “Beyond anticipation” is defined as “could not anticipate”, and on the other hand, “without anticipation” means “did not anticipate”.
The cause of the accident is “without anticipation”. To be more specific, “it was not anticipated, when it could be” or “the scope of anticipation was narrowly limited”. If the accident had been caused by the “natural catastrophe beyond anticipation”, it is concluded that natural disasters beyond anticipation that make nuclear power stations go out of control could occur. Under such conditions, resumption of the operation of nuclear power stations will be hardly acceptable to the public.
The parties concerned should feel deeply responsible, as they were without anticipation, and consider and evaluate systems both in hardware and software aspects to operate nuclear power stations more safely.
What is the sentiment of the people in Japan like at the moment?
It seems to me that the whole of Japan is maintaining enigmatic balance or a tumultuous stalemate between the following matters.
On the one hand, there is mourning for the victims of the earthquake and the Tsunami, on the other hand there is enthusiasm for “Nadeshiko Japan”, the women’s national football team that played in the World Cup, wishing restoration of the East Japan and won the cup. There is “rage” on the one hand, and “resignation” on the other. There is attachment to renewable energy such as solar power and wind power and the revival of the dependence on fossil fuel; on the other hand, there is maintenance of the energy mix including nuclear power and adherence of the commitment to reduce CO2.
If there is any solace, each force stays in balance and none is running to extremes. I hope that we can find realistic solutions after a certain period of time.
What are the next, most important, steps that should be taken, according to you? And how can these steps be realized? What are the biggest obstacles (people, economy, politics, technology)?
What is most important is the verification of the accident. It is also necessary to think about the direction of the future nuclear power stations. Therefore, things at the accident site should be rapidly brought back under control to perform internal verification. Development of the necessary technologies is also inevitable.
The greatest obstacle for the careful discussion in the future as well as today is heated scholars and commentators who repeat irresponsible comments. Not only reactor cores need cooling.
What is your opinion on the impact of the reactor catastrophe in Fukushima on future energy politics (within Japan and internationally)?
The impact of the accident is different in each country. Regarding the countries that have advanced in nuclear power, there is something like a critical point that serves as a basis for deciding whether to abandon or maintain nuclear power generation. The critical point is a value of dependence on nuclear power. The fact that Japan depends to 30% on energy of nuclear power seems to be very critical. Now Japan is as if walking on a thin fence.
On the other hand, the impact of the accident does not seem great to the countries newly developing nuclear power. The level of the impact to each country may depend on the degree of urgency in energy demand.
In any event, each country is making decisions for the national interest. A certain amount of time will be necessary for Japan to draw a conclusion, as it is the very country that is suffering from the disastrous accident and its dependence on nuclear power generation is at a critical point.
What does our energy future look like? What position does nuclear power take in it (atomic split as well as fusion)? Will the technology of atomic fusion, according to you, be ready within useful time?
We experienced the natural violence and learned from it the lesson that we have to prepare for the assumable force of nature. From our own experience, we learned that huge natural disasters that occur at lengthy intervals can occur during the time of our life. As a result, I can imagine the following scene: icebound solar panels and wind turbines, and survivors fighting a war for the little remains of natural gas.
In the long term, it is inevitable to secure energy sources independent from natural fluctuation. I personally am expecting the realization of nuclear fusion energy, but its practical use is estimated to after the middle of the 21st century at the earliest, and there are still uncertainties about this time-line. It is likely that it will take another 100 years for fusion energy to be used all over the world. Until then, efforts need to be made to increase economy of renewable energy and diffuse the use of the technology, while fission energy continues to be used at a certain level.
(Questions by Sonja Lüthi, SIA. The interview was conducted on August 5, 2011)
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