原発の状況２

NYTの最新の記事：

One major concern is that while plant operators can quickly shut down a nuclear reactor, they cannot allow the cooling systems to stop working. Even after the plant’s chain reaction is stopped, its fuel rods produce about six percent as much heat as they do when the plant is running. The production of heat drops off sharply in the following hours, but continued cooling is needed, or the water will boil away and the fuel will melt, releasing the uranium fragments inside.

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If the cooling system remains inoperative for many hours, the water would eventually boil away, he said, and the fuel would begin to melt. That is what happened at Three Mile Island. In that case, the causes were mechanical failure, operator error and poor design, government investigators later found.

現時点では緊急的な危険はない。特に放射能のリークは実質的な問題はない。問題は今後も原子炉の冷却をコントロールできるかどうかだ。

米軍が冷却材を既に日本近海に搬送したが、日本は利用を見合わせているそうだ。このまま、日本側による原発の温度低減作業が実施されるだろうが、完全な管理をとりもどせるかどうかは、外部の専門家でも分からない状態だ。

日本から米軍に冷却材が要請されるような事態にはならないと思うが、万が一の対策は立てておかなくてはならない。それがリスク管理というものだ。