#Fukushima I Nuke Plant: TEPCO to Inject Nitrogen Gas into Reactor 1's Containment Vessel

to prevent a hydrogen explosion.

(So this is "the dog"; the tail was the pit that was leaking radioactive water.)

Also read the New York Times article on the latest US assessment of the Fukushima Plant situation.

Yomiuri Shinbun (11:20AM JST 4/6/2011):

TEPCO announced on April 6 that there is a possibility of a hydrogen explosion in the Containment Vessel of the Reactor 1 at Fukushima I Nuclear Power Plant, and TEPCO will start injecting the inert nitrogen gas into the Containment Vessel as early as this evening.

According to TEPCO, both the pressure and the temperature within the reactor [Reactor Pressure Vessel] remain high, the partial exposure of the fuel rods continues, and zirconium in the cladding and the steam are reacting to create more hydrogen. As hydrogen also accumulates in the Containment Vessel as some of it escapes from the RPV, it could react with oxygen and cause an explosion.

The purpose of injecting nitrogen gas is to dilute hydrogen to avoid an explosion. According to TEPCO, about 6000 cubic meters of nitrogen will be injected over the next few days.

TEPCO will also prepare for nitrogen injection in the Reactors 2 and 3.

　東京電力は６日、福島第一原子力発電所１号機の格納容器内に水素がたまり、爆発につながる可能性があるとして、早ければ同日夕方から格納容器内に不活性の窒素ガスの注入を始めると発表した。

　東電によると、１号機は原子炉内の圧力と温度が高く、燃料棒の一部露出が続き、燃料棒の被覆管ジルコニウムと水蒸気が反応して、水素が増えているとみられる。格納容器にも漏れた水素が一定割合に達すると、酸素と反応して水素爆発の危険が高まると判断した。

　不活性の窒素ガス注入は、水素の割合を下げて、爆発を回避する狙いがある。東電によると、１号機に入れる窒素の量は約６０００立方メートル。数日かけて注入する予定。

　東電は今後、２号機と３号機にも窒素を入れる準備を進めるとしている。

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