Japanese Researcher: "Reactor 2 Suppression Chamber May Have Been Damaged in the Earthquake"

The researcher, Fumiya Tanabe, is the same one who also said back in August that the fuel of Reactor 3 had melted twice and dropped onto the Containment Vessel.

If what he says is true that the Reactor 2's Suppression Chamber broke during the earthquake, it may have grave implications for all the other nuclear reactors in Japan with the same earthquake specifications.

Reactor 2's building exterior is pretty much intact, with only one hole on the side of the building. Yet, the NISA's estimate shows this reactor may have released more radioactive materials than the other reactors (1 and 3). If the Suppression Chamber was broken as soon as the earthquake hit on March 11, that may explain it.

From Kyodo News Japanese (11/19/2011):

東京電力福島第１原発２号機で、原子炉格納容器下部の圧力抑制プールが地震の揺れで早期に損傷したか、劣化した可能性が高いとする解析結果を１９日までに、原子力安全の専門家がまとめた。

An expert in nuclear safety complied the result of the analysis by November 19 that shows the high possibility of the Suppression Chamber of Reactor 2 at Fukushima I Nuclear Power Plant having been damaged or degraded by the earthquake.

　東電は、地震による原子炉の明らかな損傷はなく、津波による電源喪失が事故原因との立場。揺れで損傷していれば、福島第１と同様に従来の耐震基準が適用されている他の原発への影響も必至だ。東電や政府の事故調査・検証委員会の調査結果が注目される。

TEPCO still maintains its position that there was no visible damage to the reactors by the earthquake, and the cause of the accident was the loss of power because of tsunami. If the reactors were damaged by the earthquake, it would affect other nuclear power plants in Japan whose anti-earthquake standards are the same as those of Fukushima I Nuclear Power Plant. A closer look at the result of investigation by TEPCO and the fact-finding committee of the national government would be warranted.

　解析したのは日本原子力研究開発機構の元研究者で、社会技術システム安全研究所（茨城県ひたちなか市）の田辺文也所長。

The researcher who did the analysis is Fumiya Tanabe, a former researcher at the Japan Atomic Energy Agency (JAEA) and the current head of the Research Institute on Safety of Technology Systems (my translation, and not the formal name of the organization; 社会技術システム安全研究所) in Hitachinaka City in Ibaraki Prefecture.

I am trying to locate the details of his findings.

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TEPCO Now Says There Was No Hydrogen Explosion at Reactor 2

From Yomiuri Shinbun (3:03AM JST 10/2/2011):

福島第一原子力発電所の事故を巡り、東京電力が社内に設置した「福島原子力事故調査委員会」（委員長＝山崎雅男副社長）の中間報告案の詳細が明らかになった。

Details of an interim report by TEPCO's internal "Fukushima nuclear accident investigation committee" (headed by Vice President Masao Yamazaki) were revealed.

　２号機で水素爆発があったとする従来の見解を覆し、爆発はなかったと結論付けた。事故を招いた津波について「想定できなかった」と釈明し、初期対応の遅れについても、「やむを得なかった」との見解を示すなど、自己弁護の姿勢が目立つ。東電は、社外有識者による検証委員会に報告案を諮った後、公表する方針だ。

The committee reversed the company's position that there had been a hydrogen explosion in Reactor 2, and now concluded there was no such explosion. As to the tsunami that triggered the accident, the committee says "it was beyond expectations"; of the delay in initial response to the accident, the committee concludes "it couldn't be helped". Overall, the report looks full of self-justification. TEPCO plans to run the report with the verification committee made of outside experts before it publishes the report.

　同原発では、１号機の原子炉建屋が３月１２日午後に水素爆発を起こしたのに続き、１４日午前に３号機が水素爆発した。さらに１５日早朝、爆発音が響き、４号機の建屋の損傷が確認された。爆発音の直後に２号機の格納容器下部の圧力抑制室の圧力が急落したため、東電は２、４号機でほぼ同時に爆発が起きたとし、政府も６月、国際原子力機関（ＩＡＥＡ）に同様の報告をしていた。

At Fukushima I Nuclear Power Plant, the Reactor 1 reactor building blew up in a hydrogen explosion in the afternoon of March 12, followed by a hydrogen explosion of Reactor 3 in the morning of March 14. Further, in the early morning on March 15, there was an explosive sound, and the damage to the Reactor 4 reactor building was confirmed. Right after the explosive sound the pressure in the Suppression Chamber of Reactor 2 dropped sharply, which led TEPCO to conclude that there were near-simultaneous explosions in Reactors 2 and 4. The Japanese government reported the events as such in the report to IAEA in June.

So then what does TEPCO now think happened in Reactor 2 in the early morning on March 15? Yomiuri doesn't say in the article text, but at the bottom of the illustration that accompanies the article it says:

"There was no explosion, but a possibility of some kind of damage to the Containment Vessel."

So, before TEPCO completely changes story, here's what they say happened on Reactor 2 on March 15 (from the daily "Status of TEPCO's Facilities - past progress" report, page 6):

It says "abnormal sound was confirmed near the suppression chamber" at 6:14AM on March 15.

Now, this is what TEPCO says about Reactor 4 on the same day, about the same time, from Page 16:

It says "an explosive sound was heard" at 6AM on March 15. The Reactor 4 explosion occurred before the Reactor 2 "explosion" which TEPCO now says never happened.

The two sounds are 14 minutes apart, and TEPCO now claims they misheard the second one and there was no explosion in the Suppression Chamber of Reactor 2.

(By the way, the fire spotted at 9:38AM on March 15 on Reactor 4 was never reported to the local fire department or the local government, as I reported on March 15.)

Well I can't wait to read their report and see how they explain away how Reactor 2 is supposed to have spewed more radioactive materials far and wide than any other Reactors.

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#Fukushima I Nuke Plant: Reactor 2 Containment Vessel May Have Had a Hole Right After March 11 Earthquake

according to a government researcher at Japan Atomic Energy Agency (JAEA).

Yomiuri Shinbun (9/22/2011):

東日本大震災直後に、東京電力福島第一原子力発電所２号機の格納容器が損傷、直径約７・６センチ相当の穴が開いた可能性のあることが、日本原子力研究開発機構の柴本泰照研究員の模擬実験で分かった。

The simulation done by Yasuteru Shibamoto, researcher at Japan Atomic Energy Agency, shows that the Containment Vessel of Reactor 2 at Fukushima I Nuclear Power Plant may have been damaged, and had a hole about 7.6 centimeters in diameter right after the March 11 earthquake.

　格納容器の損傷度を示す具体的な数値が推定されたのは初めて。北九州市で開かれている日本原子力学会で２１日、発表された。

It is the first time that the degree of damage on the Containment Vessel is estimated in numbers. It was announced on September 21 at the fall conference of the Atomic Energy Society of Japan in Kitakyushu City.

　柴本さんは、交流電源が喪失した後に、蒸気で注水を継続する非常用冷却装置「原子炉隔離時冷却系」（ＲＣＩＣ）の動作状況、圧力の推移など東電が発表したデータを活用。ＲＣＩＣへの水の供給源は、震災１４時間後に、枯渇した復水貯蔵タンクから格納容器の底部の「圧力抑制室」に切り替わった。

In simulation, Shibamoto utilized the data TEPCO had announced regarding the operation of the reactor core isolation cooling (RCIC) system and the change in pressure [inside the Containment Vessel]. In 14 hours after the earthquake hit, the water supply to the RCIC was switched from the condenser storage tank that had run dry to the suppression pool at the base of the Containment Vessel.

　この場合、熱が外部に逃げないため、圧力は、震災後、２日程度で設計圧力（約５気圧）の２倍まで急上昇する。しかし、実際は、圧力の上昇は緩やかで、７気圧に達するまで３日以上経過していた。

As the heat wouldn't dissipate, the pressure should have risen to about twice the design pressure (the design pressure is about 5 atmospheric pressures) within 2 days after the quake. However, in the actual data, the rise of the pressure was gradual, and it took more than 3 days to reach 7 atmospheric pressures.

I see. So when the water source was switched from the tank to the suppression pool, the pressure didn't rise because the Containment Vessel already had a hole in it. Then the suppression pool blew up on March 15.

The article doesn't say where the hole might be, or exactly when it may have been created and how.

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