Monday, March 28, 2011

#Fukushima I Nuke Plant: Reactor Pressure Vessels May Have Holes in Reactors 1, 2, 3 (Updated with Original Japanese)

(Updated with info on underground tunnel filled with radioactive water, in my latest post.)

(Updated with the original Japanese article, except for the opening paragraphs which disappeared after Asahi updated the article. Japanese, then my translation below.)


From Asahi Shinbun news about one hour ago (3:00PM JST 3/28/2011). Why the hell are they reporting it now?? The information was supposed to have been revealed in the press conference that TEPCO had past midnight on March 28, according to the article:

(The opening paragraph in Japanese is different now, though admitting the same thing, after Asahi updated the article.)


Tokyo Electric Power Company (TEPCO) admitted to the possibility in its early March 28 press conference that the steel Reactor Pressure Vessels that hold nuclear fuel rods in the Reactors 1, 2, 3 at Fukushima I Nuclear Plant may have broken. TEPCO explained the situation "Imagine there's a hole." Because of this "hole", contaminated water that's been poured into the Pressure Vessels to cool the fuel rods continues to leak, it is assumed.


In the Reactors 1, 2, and 3, the water level within the Pressure Vessels are not rising as much as desired. TEPCO admitted in the March 28 press conference that the reason why the Pressure Vessels haven't been filled with water was "probably a hole near the bottom, that's the image we have". Asked why there was a hole, TEPCO answered they did not know.

 圧力容器は燃料ペレット、燃料被覆管、格納容器、原子炉建屋と合わせた5重の放射能閉じ込め機能の中で、最も重要な位置づけだ。福島第一原発の圧力容器 は厚さ16センチの鋼鉄でできており、底部には、計測装置などを外部から差し込む貫通部などがある。その周辺から漏れている可能性が考えられる。

The Reactor Pressure Vessels (RPVs) are the most important of the 5-layer protection against radiation leak (other 4 are the fuel pellets, cladding of fuel rods, Container Vessels, and the Reactor buildings). The RPVs at Fukushima I Nuclear Power Plant is made of 16-centimeter thick steel, and it has an outlet at the bottom to insert measuring instruments. It is possible that the leak is from that area.

 東電は、水面から露出した核燃料が過熱して損傷した可能性を認めている。専門家によると、核燃料を束ねた燃料棒が損傷して崩れ、圧力容器下部に落下して かたまりになると、表面積が小さくなって効率よく水で冷やせなくなる。極めて高温になった燃料が圧力容器の壁を溶かして穴を開けた可能性もある。

TEPCO also admitted to the possibility of the exposed nuclear fuel rods overheating and damaging the RPVs. According to the nuclear experts, if the fuel rods get damaged and start to melt, it will fall to the bottom of the RPVs and settle. It then becomes harder to cool with water effectively, because the surface area is smaller. It is possible that the melted fuel rods melted the wall of the RPVs with high temperature and created a hole.

(The reference below to the TEPCO's belief in the integrity of the RPVs are removed in the updated article. This is the text that appeared in their 3:00PM article, which I copied when it appeared to my Japanese blog.)


On the other hand, TEPCO said it didn't think the RPVs are completely broken, because the pressures inside the RPVs were higher than the atmosphere. "It is not like Chernobyl where the RPV exploded and the fuels were outside the RPV." TEPCO continued to believe in the integrity of the RPVs.

The article continues, but it's not about the RPVs. So far, it's only at Asahi.


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