2012年8月23日 星期四

Cracks in the steel reactor vessels of two nuclear plants in the Belgium



Belgian paper: flaw in nuke plants found years ago
BRUSSELS (AP) — Cracks in the steel reactor vessels of two nuclear plants in the Belgium were first found in 1979, three years before they came online, a spokeswoman for the country's nuclear regulatory agency confirmed Thursday.
Belgium's nuclear regulator announced this month that ultrasonic tests had showed the possibility of hairline cracks in the steel vessel housing the reactor at the Doel 3 nuclear plant near Antwerp. The discovery of possible cracks came as the plant was offline this summer for a regular safety check.
The Federal Agency for Nuclear Control said it had also ordered the shutdown of the Tihange 2 reactor, 90 kilometers (55 miles) southeast of Brussels, for checks because it had a reactor vessel manufactured by the same company.
But De Morgen newspaper reported Thursday that the discovery of cracks in the reactor vessels was not new. It said its archives showed that it had reported that cracks had been found in the reactor vessels of both plants 33 years ago. It quoted an article it published in 1980 as saying, "question marks exist over small cracks in the inlet and outlet sections" of the reactor vessels of both plants. The paper also quoted Roger De Wulf, who was minister of labor at the time, as saying in the Senate in December 1979 that there were abnormalities and possible cracks in reactor vessels at the plants.
The flaws in the reactor vessels in Belgium may have wider implications, as other countries also have nuclear plants with reactor vessels made by Rotterdam Drydock Company. The company no longer exists.
Last week, Belgian authorities convened a meeting of nuclear experts from countries with similar reactor vessels, including the United States, France, Switzerland, the Netherlands, Germany, Spain, Sweden and the U.K., to share information on the possible cracks detected this summer by ultrasound.
Karina De Beule, a spokeswoman for Belgium's nuclear regulatory agency, told The Associated Press on Thursday that the cracks discovered in 1979 were in a different part of the reactor vessels than the possible cracks discovered this summer, and were entirely unrelated.
"They have nothing to do with the problem today," De Beule said.
She said the cracks were taken seriously at the time, and that Electrabel, the energy corporation that runs the plants, as well as Rotterdam Drydock Company, were required to submit information showing that the cracks posed no risk. That information was evaluated by the relevant authorities, including the European Commission, the EU's executive branch, and no risk was found.
The head of the nuclear regulator, Willy De Roovere, said last week that it was possible that the Doel 3 plant would never come back online. It had been projected to continue operating until 2022. De Roovere said that, for the plant to go back online, Electrabel would have to demonstrate there was no risk whatsoever.
The Tihange 2 plant is still being assessed. Belgium gets more than 50 percent of its electricity from nuclear power.
De Morgen reported that it asked De Roovere about the cracks found in 1979, but he said he remembered little of the discovery. During that period, prior to becoming a federal regulator, De Roovere managed the construction and startup of the Doel 3 plant for Electrabel, the energy corporation.


ベルギーの原発圧力容器にひび 欧米に同型20基以上


 ベルギー北部の原子力発電所で原子炉圧力容器に、ひびのような異常が見つかった。細かい安全確認をする方針で、当面は再稼働が難しい状況だ。同様の圧力容器は欧米の他の20基以上の原発でも使われているとみられ、問題は複数の国に波及しかねない。
 問題の原発は、1982年から稼働するドール3号機(加圧水型炉)。定期点検で超音波検査をした結果、圧力容器の壁の内部に長さ1~2センチのひびのよ うなものが大量に見つかった。ベルギーの原発規制当局は数について調査中というが、地元報道は「8千個に及ぶ」と伝えた。
 規制当局は「放射能漏れの恐れはない」としているが、原発事業者に細かく調べるよう求めており、再稼働には安全性が十分に確認されることを条件とした。
 ドール3号機はもともと2022年までに止める予定だったが、調査の結果次第では、原発の停止が前倒しになる可能性もある。

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