2013年4月23日 星期二

沒完沒了的日本核災後果

沒完沒了的日本核災後果
TEPCO rejects ministry's demand to pay 10.5 billion ...

Radioactive mud in Fukushima school pools tops...
FUKUSHIMA—Radioactive cesium levels exceeding 100,000 becquerels per kilogram were measured in mud accumulated at the bottom of swimming pools at two high schools in and around Fukushima city.
 
Radioactive water leaked from the No. 2 and No. 3 underground tanks, shown with dotted lines, at the Fukushima No. 1 nuclear power plant. The photo was taken on April 7. (Yosuke Fukudome)
Fukushima workers treated water leaks without...
Fourteen workers treated radioactive water leaking at the crippled Fukushima No. 1 nuclear plant without wearing personal dosimeters as required, Tokyo Electric Power Co. said April 19.
 IAEA inspects Japan's crippled nuclear plant
 IAEA reviewing cleanup at damaged Fukushima nuke...



IAEA稱福島核電冷卻系統需改善


東京——聯合國(United Nations)核監管機構周一稱,日本曾發生過事故的福島核電站的運營商不應該再依賴臨時措施,應當為突髮狀況做好準備。與此同時,該核電站的一個冷卻系統再次因為一隻死老鼠而被關閉。
國際原子能機構(International Atomic Energy Agency)的工作組讚揚核電站的運營商東京電力公司(Tokyo Electric Power Company,簡稱東電)維持住了福島第一核電站(Fukushima Daiichi)的穩定,並且在拆除核電站三個受損核反應堆的複雜工作上取得了進展。兩年前的大地震和海嘯使反應堆的冷卻系統陷入癱瘓,導致反應堆的堆芯 熔毀;該事故使日本東北地區全境受到了輻射影響。
國際原子能機構核燃料再生與廢棄技術部長、工作組組長鬍安·卡洛斯·蘭蒂赫(Juan Carlos Lentijo)說,東電公司已經完成了最緊急的任務,在非常困難的高輻射條件下完成了冷卻受損反應堆的工作。他還說,儘管如此,“還有改善的空間。”

他說,雖然東電公司一直致力於使核電站變得更加安全,採用的手段卻往往是“臨時系統或移動系統——因此,那裡需要更為持久的系統”。

本周一,部分冷卻系統的權宜性質再次顯現。當天,東電公司表示,因為在設備附近發現了死老鼠,他們已經暫時關閉了一個冷卻系統。該系統被關閉了四個小時,在此期間,工作人員確定電路並未受損。
上月,一隻死老鼠引發的短路曾讓一個類似冷卻系統被關閉了一天多的時間。
東電公司稱,這兩次關閉都沒有帶來任何危險,因為這些系統是存儲乏燃料的冷卻池,乏燃料釋放的熱量相對較少,即便停止冷卻一周也依然安全。
此外,該電站地下蓄水池內重度污染的水曾發生多次泄漏。雖然泄漏的水量通常比較小,這些事故還是讓人們擔心,東電公司維持核電站穩定的努力是否足夠。
聯合國原子能機構的蘭蒂赫稱,東電公司需要對感應器和其他的故障探測設施進行升級,這樣才能做出更及時的回應。他稱,在繼續清理損毀的反應堆時,加強處理突發事件的能力對東電公司來說至關重要。清理工作很複雜,可能要持續40年。
蘭蒂赫表示,該公司目前面臨的最大挑戰是處理核電站內不斷增加的大量含輻射水。每天約有10萬加侖(約37.9萬升)的地下水流進損毀的反應堆建 築,隨即受到污染。蘭蒂赫稱,他的小組已經給東電公司提出建議,指導他們如何安全地將水儲入水罐和業已佔據該核電站大部分地下空間的地下蓄水池。
翻譯:陳柳、張亮亮


Fukushima Plant Operator Should Prepare Better, U.N. Watchdog Says


TOKYO — The operator of Japan’s stricken Fukushima nuclear plant should stop relying on stopgap measures and better prepare for the unexpected, the United Nations nuclear watchdog agency said Monday, even as a cooling system at the plant was once again shut down because of a dead rat.
A team from the International Atomic Energy Agency praised the operator, Tokyo Electric Power Company, for stabilizing the Fukushima Daiichi plant and making progress in the complex task of dismantling its three damaged nuclear reactors. A huge earthquake and tsunami two years ago knocked out the reactors’ cooling systems, causing their cores to melt down; the accident spewed radiation across northeastern Japan

Juan Carlos Lentijo, the director of the nuclear fuel cycle and waste technology division at the agency and the team’s leader, said that the company had accomplished the most urgent job, cooling the damaged reactors, in very difficult conditions of high radiation. However, he said, “there is still room for improvement.”

He said that while the company, called Tepco for short, has been working to make the plant safer, it was often doing so “with temporary systems or mobile systems — there is a need for more permanent systems.”

The makeshift nature of some of those cooling systems was exposed again on Monday when Tepco said it had temporarily switched off one of them after a dead rat was found nearby. The system was off for four hours while workers made sure there was no damage to electrical circuits.
Last month, a short circuit caused by a dead rat shut down a similar cooling system for more than a day.
Tepco said that neither shutdown created any danger, because the systems were cooling pools containing spent fuel, which give off relatively low levels of heat and would remain safe even if left uncooled for a week.
There have also been a number of leaks of highly contaminated water from underground storage pools at the plant. Though the leaks have generally been small, they have raised public concerns about whether Tepco was doing enough to stabilize the plant.
Mr. Lentijo of the U.N. agency said that Tepco needed to upgrade sensors and other mechanisms for identifying problems so that it could respond more promptly. He said it was essential for Tepco to strengthen its ability to cope with unexpected events as it continues to clean up the damaged reactors, a complex job that may take 40 years.
Mr. Lentijo said the company’s biggest immediate challenge was managing the huge and growing amount of radioactive water at the plant. Some 100,000 gallons of groundwater a day enters the damaged reactor buildings and becomes contaminated. Mr. Lentijo said his group gave Tepco advice on how to safely store the water in tanks and underground pools that now occupy much of the grounds of the plant.

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