Core Shroud of Mühleberg Nuclear Power Plant Was Found with a Huge Crack in 2009, Operator and Swiss Government Hid the Fact, Says Japan's Mainichi

(UPDATE) According to Switzerland's Beobachter (in German), the cracks are along the horizontal weld of the shroud, not "top to bottom" as Mainichi describes. The core spray system was also found with cracks. (H/T Atomfritz)

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More on Mühleberg Nuclear Power Plant in Switzerland, whose license to operate will be withdrawn in June 2013 by the court order (see my previous post).

Japan's Mainichi Shinbun (3/8/2012; link goes to a message board with full copy of the article) reports that the plant operator BKW Energy and the nuclear regulating agency of the Swiss government hid the discovery in 2009 of a huge crack in the core shroud inside the Reactor Pressure Vessel.

From Mainichi Shinbun article (part):

ところが、福島原発事故後の昨年６月、地元メディアが、ミューレベルク原発の圧力容器内にある炉心シュラウドという高さ９メートルのステンレス製構造物に、上から下まで貫通するひび割れができていると報道。連邦核安全監督局は「ひび割れがあっても安全基準は満たされており、問題ない」と危険性を否定した。

However, the local media reported in June last year in the wake of the Fukushima I Nuclear Power Plant accident that the 9-meter high stainless-steel core shroud inside the Reactor Pressure Vessel at Mühleberg Nuclear Power Plant [there is only one reactor] had a crack from top to bottom. The federal nuclear safety regulation agency denied the risk, saying "Even if there is a crack, [the shroud] meets the safety standard, and there is no problem."

　これを、反原発団体などが「炉心シュラウドは燃料棒や制御棒を囲んでいる大事な構造物で、損傷によって燃料棒がずれるなどの危険がある」と批判。ひび割れが０９年には見つかっていながら公表していなかったことへの不信感も加わって、行政裁判所に対し、連邦政府が０９年に出した運転許可を無効にするよう求め提訴した。この日の判決で裁判所は、反原発団体の訴えをほぼ全面的に認めた。

Anti-nuclear groups criticized the comment, saying "The core shroud is an very important structure that surrounds nuclear fuel rods and control rods. The damage may cause the fuel rods to shift." The crack had been discovered in 2009 but it was not disclosed. The anti-nuclear group(s?) filed a suit in the Federal Administrative Court demanding the withdrawal of the operation license issued by the federal government in 2009. With the ruling [on March 7], the Federal Administrative Court upheld the complaint from the group.

The crack in the core shroud was found in 2009, in the same year that the government granted the operator an open-ended (indefinite) operation license. I wonder which came first.

Mainichi also reports that BKW Energy plans to appeal to the Swiss supreme court.

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"Now They Tell Us" Series: #Fukushima Reactor Cooling Was From Outside the Shroud

Here I thought they'd been injecting water directly above the melted fuel or where the fuel had once been.

TEPCO in its daily press conference on July 26 said the cooling of the three reactors at Fukushima I Nuclear Power Plant has been done by cooling the core shrouds from outside. The shroud is a cylinder inside the Reactor Pressure Vessel (RPV) that surrounds the reactor core. (The image is from Toshiba.)

Either they tell us now, or it occurred to no one to ask in detail how the fuel was cooled.

Mainichi Shinbun Japanese (7/26/2011):

東京電力は２６日、福島第１原発３号機の原子炉内にある核燃料を効率良く冷やすため、注水方法を変更するための作業を始めたと発表した。核燃料のより近くに注水できる配管が使用できるかどうかを調べるため、国産ロボット「クインス」を原子炉建屋に入れて調査した。

TEPCO announced on July 26 that the company started the work to change the method of water injection in order to cool the fuel inside the Reactor 3 more effectively. The Japanese-made robot "Quince" went inside the reactor building to investigate whether it was possible to use the pipe that could feed water closer to the nuclear fuel.

　１～３号機では、炉心を囲む構造物「シュラウド」の外側に冷却水を流して核燃料の温度を下げている。１、２号機は毎時４立方メートル弱の注水で一定の効果が出ているが、３号機では効率が悪く同９立方メートルを注水している。

In Reactors 1, 2 and 3, the cooling water is being poured outside the core shroud to lower the temperature of the fuel. The method is adequate in Reactor 1 and 2 with about 4 tonnes/hour water injection, but in Reactor 3 this method of cooling is not efficient enough, and it requires 9 tonnes/hour water.

　しかし、その分、汚染水が大量発生しやすく、新たな対応が必要になってきた。そこで、東電は核燃料の真上から注水する緊急炉心冷却装置 （ＥＣＣＳ）の配管などを使うことを検討。同日、建屋１、２階にクインスを入れ配管を撮影したほか、作業員が入れるかどうか周辺の放射線量の測定を始め た。

As the result, more contaminated water is being produced, and the company was looking for an alternative method of cooling. TEPCO is considering using the ECCS (emergency core cooling system) pipe which can pour water from above the fuel. On July 26, the company sent the robot "Quince" to the 1st and 2nd floors of Reactor 3 building to take pictures of the pipe, and started measuring the radiation levels to see if workers could enter the building.

As far as TEPCO is concerned, the melted core is still inside the RPV in Reactor 3.

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