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2011-03-26

〔★原発NEWS〕 「3号機」 解放バルブ 開きっ放しも

 「憂慮する核科学者たち(UCS)」の直近(24日午前11時から=日本時間25

日午前1時から)のブリーフィングで、「3号機」の状況についてロクバウム博士は、「データを見る限り、今、何が起きているか、結論付けるわけにはいかない」と最終断を留保しつつも、「たとえば解放バルブのひとつが開きっ放しになっていることも考える」との見方を示した。

 これが実際に起きているとすれば、それはつまり圧力容器の密封が破れているわけだが、こうした事態で最もありうるのは、炉心の溶解まで破壊が進んでいることだ。溶解したものは容器の底にたまり、穴が開く。圧力容器の破砕だ。炉心の燃料棒が火ぶくれや亀裂を走らせる段階を超えた、深刻な核燃料へのダメージである――と博士は語った。

 (博士が可能性として示したこの見方は、これまでにすでに日本の専門家が指摘していたことである。その見方を、最終判断を留保しながら、博士が示したことは、日本の専門家の見方を確証するものとして意味がある) 

 REPORTER:  Hi, thanks for doing this.

I'm seeing these sort of ominous reports from the Japanese Prime Minister, you know, warning of a breach in the reactor vessel of Unit 3, can you give us some kind of context to understand why, you know, how risky that is and just give me some sense of, you know, we've been hearing about this for weeks now and I actually, I mean, just give me a sense of what you guys know about this breach and what it could mean.

 MR. LOCHBAUM:  This is Dave Lochbaum, I'll start and then Ed can supplement. First of all, we're hearing reports of a reactor vessel breach on Unit 3, but the data is inconclusive as to whether that's actually what's going on.  There could be other factors that could cause the reactor vessel integrity to be lost, for example, one of the relief valves could have stuck open. If it is, indeed, a reactor vessel breach, the consequences, or the most likely reason for that would be that the core has been damaged to the point of melting.  Some of the molten mass fell down to the bottom of the reactor vessel and caused a hole, burned a hole or created a hole in the bottom of the reactor vessel, which became the breach. If that's the case, it's bad, because first of all, it indicates that the level of fuel damage went beyond blistering and cracking of the fuel rods, to the point of melting of fuel, which is a more severe form of fuel damage.  And it was followed by a loss of integrity of the reactor vessel. If the reactor vessel remains intact, you always have the option or the ability to put water back into it to cool the fuel, even if it's damaged.  If the reactor vessel has been breached, you face challenges in putting enough water in it and keeping the water in it rather than having it just drain back out through a hole in the bottom.
 
I n the emergency procedures world, if you do lose the integrity of the reactor vessel, the option is to fill up the entire containment above the point where the breach has occurred so that you try to still cover up the fuel, even if the fuel has been relocated, part of the fuel may have relocated, and the reactor vessel integrity has been lost. So, you still have methods to deal with that, if that were to occur, but they're obviously much more severe than if you keep the reactor vessel intact and allow the fuel to remain where it was placed originally.

 ⇒ http://www.ucsusa.org/nuclear_power/nuclear_power_risk/safety/nuclear-crisis-japan-telepress-transcript-03-25-11.html

Posted by 大沼安史 at 09:23 午前 |

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