As we mark the fourth summer since the tragic megaquake of March 2011, a clear consensus has emerged among experts in the field on the cause of the accident at the Fukushima 1 Nuclear Power Plant. That consensus is that the accident was not caused by the initial quake, but rather by the tsunami that followed.

　　　At a symposium sponsored by the Science Council of Japan on May 14th in which representatives from the government, the Atomic Energy Society of Japan, the Japan Society of Mechanical Engineers, and other organizations participated, paper after paper was presented that concluded that the reactor and piping system of the Fukushima facility had withstood the initial impact of the 9.0 magnitude quake without damage.

　　　Mitsuhiko Tanaka, former committee member of the Fukushima Nuclear Accident Independent Investigative Committee of the Diet (NAIIC), was the only one present at the May 14th symposium to not agree with the general consensus, asking, “How can you oppose the findings of the NAIIC, which is the authoritative body on this matter?”

　　　On July 18th the Nuclear Regulation Authority (NRA) held its sixth review meeting on the Fukushima accident. Based on on-site investigations and a survey of electronic records, the NRA issued an interim report finding that damage to the piping system had not been caused by the quake, putting it in opposition to the findings of the NAIIC.

　　　The NRA’s findings elicited a quick response from Tanaka and some of his allies on the NAIIC, with a letter being sent on July 23rd demanding that Tadashi Narabayashi, a professor at Hokkaido University and a key outside expert in the NRA’s investigations, cease his work for the Authority.

　　　The letter was sent from Tanaka and Katsuhiko Ishibashi, Tanaka’s co-chair of Working Group I of the NAIIC––together with the signatures of members Shiro Ogura and Yoshinori Ito––to Professor Narabayashi and Shun’ichi Tanaka, chairman of the NRA. Copies were sent to all of the major media outlets as well as Eisuke Mori, chairman of the House of Representatives Special Committee on Nuclear Power, and Motoyuki Fujii, chairman of the House of Councilors Special Committee on Nuclear Power.

　　　Right from the start, Professor Narabayashi has been among the most rational and scientifically sound of those speaking out on the Fukushima accident.  When the Kan administration was still denying soon after the accident that there had been a meltdown, Narabayashi was the first to insist that there had indeed been one.  Later, as the investigation of the accident proceeded in more depth, Narabayashi refused to be swayed by the sterile ideologies of either the pro- or anti-nuclear camps, sticking to a strictly scientific approach in his research and analysis.

A “SHEET OF WATER” OR A “BUCKET OF WATER”?

　　　Tanaka is demanding that Narabayashi be removed from his role in the NRA’s investigations because of what he said at the July 18th review meeting.  Tanaka claims that Narabayashi’s statement “could not be overlooked,” as it showed “considerable contempt for Working Group I” and “demeaned the findings of the NAIIC.”

　　　What Tanaka took exception to is this statement from Narabayashi: “I have heard that there may have been some ‘leading of the witness’ in the testimony given to the NAIIC.  This could lead to charges of wrongdoing, and so I would like to have some clarification.  What is the basis of these rumors, and are they true or not?”

　　　To outsiders, what Narabayashi is really driving at here is not clear. More background can be found in Tanaka’s letter, however, where he quotes Narabayashi as claiming that the testimony of an eyewitness concerning the overflow of water on the fourth floor of Reactor 1 was “coerced.”  The eyewitness in question is quoted as saying that a “sheet of water came rushing in.”(The original Japanese says “a sheet of water the size of a tatami,” which would be about 3 x 66 feet and 2.25 inches thick.) But if one reads Narabayashi’s statement above, one can see that he is only trying to clarify how the Investigative Committee’s interviews were actually conducted.

　　　Why is Narabayashi’s question so important?  The answer lies in the fact that the overflow of water referred to occurred after the quake but before the tsunami.  If there actually was a “sheet of water rushing in,” then that means there was damage to the piping system before the tsunami, validating the findings of the NAIIC. However, the eyewitness who gave this testimony had this to say when asked about his statement:

　　　“The best explanation I can give is that it was like a ‘bucket of water being tipped over.’ When I met with the representatives of the NAIIC, I was asked, ‘For example, was it like a sheet of water?’ Since that’s the way they put it, I said it might have been something like that, and that’s how it was recorded in their report.” (Review of Accident at Fukushima 1 Nuclear Power Plant: Minutes of Meeting 2, page 20)

　　　Was it a “sheet of water” or something on a much smaller scale like a bucket of water?  The difference between the two is very large, likely the difference between a rupture in the piping system and water from the pool on the floor above being rocked into a duct and seeping down.  The eyewitness says that a “bucket of water” is the correct description. In other words, there was absolutely no damage to the reactor at the time of the quake.

　　　If the piping system had been damaged, the hot water of the reactor would have leaked, the surrounding area would have been engulfed in steam, and there would have been a deafening roar. But there is no testimony of anything of the sort happening. In fact, the opposite occurred, with the emergency isolation condensers continuing to function until flooded by the tsunami, managing to lower the pressure from 75 atm to 46 atm in fifteen minutes and then raise it back up to 70 atm.  If there had been a rupture in the piping system, the facility operators would not have been able to decrease and increase the pressure in this way. There was no damage to the piping system.

CALL FOR NARABAYASHI TO WITHDRAW HIS STATEMENT

　　　Mitsuhiko Tanaka is strongly in the anti-nuclear camp and his fierce reaction to Narabayashi’s statement, demanding that he step down from participation in the NRA’s investigations, reflects that political position.  If Narabayashi’s line of inquiry proves correct, then the argument that the piping system was ruptured by the quake falls apart––and if that argument falls apart, then the argument that all of Japan’s nuclear plants are in danger from future quakes also falls apart.  For the anti-nuclear camp, this must indeed be a difficult pill to swallow.  It is not surprising that their attacks on Narabayashi have been so vicious.

　　　Even at that, it is strange indeed that at the same time that Tanaka is bandying about the authority of the NAIIC in demanding that Narabayashi step down, no where in his letter can be found the name or signatory chop of Kiyoshi Kurokawa, the chairman of the NAIIC. Did Kurokawa in fact agree with this move to condemn Narabayashi as “an outside expert totally lacking in the necessary qualifications?”

　　　Of even more concern are the actions of the Nuclear Regulation Agency.  (The Nuclear Regulation Agency acts as the bureaucratic liaison within the Ministry of the Environment for the Nuclear Regulation Authority, an independent body.) Panicked by the letter from Tanaka and his allies, the Agency asked Narabayashi to write a public letter of apology and withdraw his statement.

　　　An indignant Narabayashi replied: “This kind of request coming from the Nuclear Regulation Agency is the one thing above all that I cannot accept.  The independence of the Nuclear Regulation Authority must be respected and guaranteed.”

　　　Nuclear regulatory bodies around the world are composed of experts in the field, and within these bodies the commitment to sound scientific methods is prized more than anything.  Here in Japan we must also ensure that this is the case.

　　　Finally, I must point out that all of the materials related to the NAIIC investigations are being held in the Diet library, but have not yet been opened to the public.  The release of these materials will help to prevent the reoccurrence of such a disaster.  They must be made available to the public with all due speed.

(Translated from Renaissance Japan column no. 618 in the August 14-21, 2014 combined issue of The Weekly Shincho)