Monthly Archives: February 2017

Risque de catastrophe au réacteur 2 de Fukushima Daiichi : quelles conséquences pour le Pacifique et les USA ?

Source : Asahi Shimbun

 
À la centrale dévastée de Fukushima 1, Tokyo Electric Power Co. Holdings Inc. révèle que le niveau de radiation dans l’enceinte de confinement du réacteur 2 avait atteint 530 sieverts par heure (Sv/h), le taux le plus élevé qu’on ait mesuré depuis la fusion des trois cœurs en mars 2011.

À ce taux de 530… Continue reading

福島第一原発二号機が引き起こしかねない大惨事 太平洋と米国への影響や如何?

(翻訳:神学博士 川上直哉)

朝日新聞英語版より

朝日新聞英語版より

事故により破損した福島第一原子力発電所の第二号機格納容器内の放射能レベルは最大で530Sv/hにまで達した。これは2011年3月の事故によって三つのメルトダウンが起こって以来最大の数値であると、東京電力会部式会社(TEPCO)は語った。

530Sv/hとは、ごくわずかな時間の被ばくによって人が死亡するレベルである。この放射能の数値は、2011年3月に破損した三つの原子炉すべてを解体する困難の巨大さを示している。原子炉取り出しの方法を見出さなければならない日本政府とTEPCOは、まさに困難な現実を突き付けられた格好だ。

国立研究開発法人 放射線医学総合研究所(放医研)の公式見解によると、放射線を取り扱うどんな医療関係者も、これほどのレベルの放射能を取り扱うことについては、考えることもできないという。

TEPCOはまた、カメラの遠隔操作によって得られた映像を分析したところ、原子炉の第一格納容器の中にある圧力容器の下には、金属製の格子の中に2メートルの穴があった、とも報告した。

放射能、3.11以来最大に
2017年2月3日付 ジャパンタイムス

画像分析によると、福島第一原発二号機内格納容器の中の圧力容器の下にある格子に2メートルの穴が空いている。(画像は東京電力)

画像分析によると、福島第一原発二号機内格納容器の中の圧力容器の下にある格子に2メートルの穴が空いている。(画像は東京電力)

原子力の安全対策を専門とするタナベ フミヤ氏によると、この画像分析によって、廃炉作業の準備とその具体的作業は、当初考えていたよりもさらにずっと難しいものだと分かった、という。なお、タナベ氏は1979年に米国スリーマイル島で起こった原発事故を分析した経験を持っている。 
– “Radiation Level in Fukushima Reactor could kill within a minute”, 「福島原発の原子炉内放射能は一分以内に人を殺傷するレベル
2017年2月3日 朝日新聞英語版
損傷した福島第一原発二号機の格納容器内の放射能レベルは、専門家が信じていたよりも格段に高いものであったことが、今や、明らかとなりました。

二号機の危機を前に、私は一つの恐ろしい記憶をよみがえらせています。それは2011年3月の地震の後に福島第一原発四号機が引き起こしかねなかった大惨事です。四号機は、ヒロシマ型原爆の14000倍に相当する放射能をその内側に蔵していたのでした。

二号機の危険性は今、私たちにいくつもの問いを持って迫っています。

    The Potential Catastrophe of Reactor 2 at Fukushima Daiichi: What Effect for the Pacific and the US?

    français | 日本語訳    

    Source: Asahi Shimbun

    Source: Asahi Shimbun

    The radiation level in the containment vessel of reactor 2 at the crippled Fukushima No. 1 power plant has reached a maximum of 530 sieverts per hour, the highest since the triple core meltdown in March 2011, Tokyo Electric Power Co. Holdings Inc. said.
    
    At 530 sieverts, a person could die from even brief exposure, highlighting the difficulties ahead as the government and Tepco grope their way toward dismantling all three reactors crippled by the March 2011 disaster.
    
    An official of the National Institute of Radiological Sciences said medical professionals have never considered dealing with this level of radiation in their work.
    
    Tepco also announced that, based on its analysis of images taken by a remote-controlled camera, that there is a 2-meter hole in the metal grating under the pressure vessel in the reactor’s primary containment vessel. It also thinks part of the grating is warped.
    
    -  "Highest radiation reaching since 3/11 detected at Fukushima", Japan Times, February 3, 2017 .

     

    Based on image analysis, a two-meter hole has been found in the metal grate under a pressure vessel in reactor No. 2's containment vessels at the Fukushima No. 1 nuclear power plant. Image: Tokyo Electric Power Company

    Based on image analysis, a two-meter hole has been found in the metal grate under a pressure vessel in reactor No. 2’s containment vessels at the Fukushima No. 1 nuclear power plant. Image: Tokyo Electric Power Company

    Fumiya Tanabe, an expert on nuclear safety who analyzed the 1979 Three Mile Island nuclear accident in the United States, said the findings show that both the preparation for and the actual decommissioning process at the plant will likely prove much more difficult than expected.
    
    - "Radiation Level in Fukushima Reactor could kill within a minute", Asahi Shimbun, February 3, 2017.

     

    It is clear to us now that the radiation level in the containment vessel of the crippled Reactor 2 is much higher than experts had believed.

    The danger of Reactor 2 reminds me of the story of the potential collapse of Reactor 4 after the March 11, 2011, earthquake. That reactor contained 14,000 times the radiation of the Hiroshima bomb.

    The danger of Reactor 2 begs us to ask many new questions:

    • What is the probability of next strong earthquake?
    • What is the earthquake resistance of the building that houses the reactor?
    • How do we find the location of the irradiated cores in the pressure vessels?
    • If it collapsed, what is appropriate evacuation distance?
    • What is the the damage to ocean marine life?
    • What are the potential risks to children and people on the West Coast of North America, who may be affected by the flow of much stronger contaminated water into ocean from Fukushima?

    I am very pleased that Dr. Shuzo Takemoto — professor of the Department of Geophysics, Graduate School of Science, Kyoto University — responded to my concerns. I share his perspective below.

    – Akio Matsumura

    Potential Global Catastrophe of the Reactor No.2 at Fukushima Daiichi
    by Professor Shuzo Takemoto

    On July 28, 2016, the Tokyo Electric Power Company (Tepco, the utility that operates the reactors) published the images of the F1 Unit 2 reactor screened by muon particles coming from the universe — similar to an X-Ray. They showed the shadow of materials equivalent to 180 – 210 tons at the lower part of the pressure vessel. Consequently, Tepco concluded “Most of the nuclear fuels are estimated to remain in the vessel.”

    Muon imaging setup for Fukushima Daiichi Unit 2. FMT-2 is installed inside a concrete radiation shield in front of the reactor building. Typical muon scattering angles are a few degrees.

    Muon imaging setup for Fukushima Daiichi Unit 2. FMT-2 is installed inside a concrete radiation shield in front of the reactor building. Typical muon scattering angles are a few degrees.

    It can hardly be said that the Fukushima accident is heading toward a solution. The problem of Unit 2, where a large volume of nuclear fuels remain, is particularly crucial. Reactor Unit 2 started its commercial operation in July 1974. It held out severe circumstances of high temperature and high pressure emanating from the March 11, 2011, accident without being destroyed. However, years long use of the pressure vessel must have brought about its weakening due to irradiation. If it should encounter a big earth tremor, it will be destroyed and scatter the remaining nuclear fuel and its debris, making the Tokyo metropolitan area uninhabitable. The Tokyo Olympics in 2020 will then be utterly out of the question.

    The number of nuclear fuel rods in the cooling pool are as follows; Unit 1: 392, Unit 2: 615, Unit 3: 566. In ordinary times, these fuel rods can continue to be cooled if electricity is secured to pump water. We are filled with anxiety when we think of a power failure and of a strong earthquake befalling them, and of their consequences.

    The earthquake of November 22, 2016, off the coast of the Fukushima Prefecture (magnitude 7.4) and the earthquake of December 28, 2016, in the Northern part of the Ibaragi Prefecture (magnitude 6.3) are situated in the aftershock area of the 2011 earthquake off the Pacific coast of Tōhoku. In this area, we must foresee a number of magnitude 7 class earthquakes. Consequently, we cannot exclude the possibility of intensity 6 and intensity 7 earthquakes befalling the Fukushima Daiichi. What is most dreaded is what could happen to the Unit 2 whose pressure vessel contain a large volume of nuclear fuel debris.

    This pressure vessel has endured the sudden change of temperature and pressure in the accident of March 2011, but in light of its possible weakening due to irradiation, it could be seriously damaged if a new big earth tremor occurs nearby.

     

     

    Quel rapport entre les centrales nucléaires et les armes nucléaires ?

    Après la catastrophe nucléaire de Fukushima, j’ai réalisé une chose importante: nous n’avons pas voulu voir que les radiations provoquées par les bombes atomiques et celles qui proviennent d’un accident nucléaire sont extrêmement similaires en termes de risques pour la vie humaine. Il ya longtemps que nous admettons les dangers des attaques à l’arme nucléaire quand elles sont perpétrées par des États et aujourd’hui nous comprenons la menace que représentent