Published on May.26 ,2014 : The Denki shinbun(The Electric Daily News)
Dr. Michio Ishikawa
Chief Adviser(Former President & CEO of JANTI

The Denki Shimbun recently published my book titled “A Study of the Fukushima Nuclear Accident: How did the core melt and hydrogen explosion occur?” It took 14 months to publish the book after starting my investigation. This is because I was only able to obtain a few recollections which would serve as a key to explaining the accident, and finding evidence was difficult.

For instance, there are many testimonies about the Chernobyl accident mentioning things such as “along with the sound of the explosion, there were sparks doing a devil’s dance in the skies above the power station.” These recollections provide evidence to support the facts that the ejection of steam lasted a certain period of time and that the sparks were fragments of high-temperature fuel materials, in a way that brings the scene to life. Such testimonies do not exist for Fukushima.

Since the cause of the accident was a loss of power, I was prepared for a lack of data. Using the progression of the TMI accident, which experienced a core meltdown like Fukushima, as an example, the progression of the Fukushima accident gradually became clearer to me as I pored over the data.

As this was a book on explaining the accident, I eliminated speculation as much as possible. I supplemented missing data with results from the experiments conducted in the 1970’s by the United States,Germany and Japan regarding the research of safety on “fuel behavior during an accident”, as well as the facts of the TMI and Chernobyl accidents. I believe that this allowed me to at least figure out a rough outline of the progression of the accident.

Some of the extra insights that did not make it into this book, such as ideas, discoveries, and troubles that I had during the long review process will be featured in this column in the future. For this accident, there were few personal testimonies. This is because the interviews conducted by the government accident investigation committee became testimony, and the mass media reported that false testimony would be a court case. Power companies tend to be incommunicative to begin with. Fearing problems caused by inconsistent testimonies, they kept silent. There was no way to get them to budge. This suppressed the fresh memories of people immediately after the accident. Even a supporter of nuclear power such as me could not get an answer from them.

A specific example of this is the location of sea water injection. The fact that they remain secretive about something such as this makes me more sad than annoyed. I obviously thought that the water injection was done by spraying from the upper core. In this case, it would be incompatible with the experimental facts unless the core collapsed at the same time as water injection. The accident phenomenon is chronologically incoherent.

After two months of being at a loss, I happened to find out that the water was injected from the bottom of the core, and my question was immediately resolved. The answer brought joy but at the same time was anticlimactic. If water injection was conducted from below, it would take time for water to reach the core. The calculations would fit the phenomenon, and everything would be explained.

A second example was the fact that the time that the surrounding background radiation dose increased (4:00am on the 12th) was earlier than the time that the Unit 1 vents were opened (2:30pm on the 12th). This phenomenon is illogical. Actually, I had misread the report and overlooked the work record which stated that the fire hose was connected to the feedwater line at 4:00am. However, such an oversight can normally be resolved with a simple phone inquiry.

Connecting a hose to the pipe means creating a path for radiation to leak outside from the reactor. This connection work was what caused an increase in the radiation dose.

A third example is that TEPCO announced a correction last December during the final revision of this book, saying that there was a branch to the sea water injection line, and that the amount of sea water injected into the reactor was not clear due to a leakage of this line.

This announcement was a saving grace. I won’t mention the details, but the Unit 3 water level data and the amount of water injected, according to my calculations, were not consistent, and I was having difficulty interpreting this inconsistency. I reluctantly abandoned my calculations, and wrote in the book an account of the accident where the data was correct. The TEPCO announcement was a salvation from this anxiety, and proved that this choice was reasonable.

As you can see, the information that serves as key to explaining the accident is trivial information. Such information is hard to notice, but not matters that should be hidden. The government accident investigation committee created an atmosphere in which not even such trivial information could be revealed. It is natural that there are discrepancies in the testimonies given under such chaotic circumstances. It is the committee’s job to distinguish and determine the correct testimonies. Their rigid and public-pandering approach is what caused the investigation to fail. The fresh eyewitness accounts that were lost cannot be recovered. This is still hindering the path to shedding light on the accident. I strongly urge the government to make improvements for the future.

end