THORPの強いリキュール update4　弁財天

英セラフィールド再処理工場(Thorp)が閉鎖された理由はコストの問題の他に

再処理で使用済み核燃料より強い放射線の廃液ができること。
Thorpを稼動させ続けるために追加で6億ポンド(約850億円)のプールの建設が必要になるから。

ハンフォードとセラフィールドの再処理工場に共通する失敗は再処理の過程でできる使用済み核燃料より強い放射性の酸の廃液がプラントやプールを溶かし漏れてしまったこと。そして再稼動できなくなり赤字拡大。六ヶ所再処理工場がどうなるかわかっちゃったな。

Cumbria’s reprocessing plant to close

June 7, 2012 7:42 pm
Cumbria’s reprocessing plant to close
By Rebecca Bream

One of the more problematic facilities in the UK nuclear industry, the Thorp reprocessing plant at Sellafield in Cumbria, is set to close, reflecting a worldwide drop in demand for its services.

The Nuclear Decommissioning Authority, which is responsible for cleaning up the UK’s nuclear reactor sites and dealing with radioactive waste, said on Thursday that Thorp would close in 2018 when its existing reprocessing contracts end.

Thorp -- which stands for Thermal Oxide Reprocessing Plant -- was opened in 1997 and reprocesses spent fuel from nuclear reactors in the UK as well as countries including Japan, Germany, Italy, Switzerland and Belgium. It separates off uranium and plutonium, which can both be reused, to leave radioactive waste, which is treated and stored at Sellafield.

But demand for reprocessing has been hit by the relatively low cost of newly-mined uranium, the price of which rose sharply in 2007 but fell again during the financial crisis.

Thorp’s profitability has also been hampered by its patchy performance, most notably its three-year closure after a leak of radioactive acid from a holding tank into the surrounding concrete containment shell in 2005.

British Nuclear Group, which was then in charge of running Sellafield, said the incident posed no danger to the public but admitted the leak had remained undetected for months.

Extending Thorp’s life would require investment “well in excess of £1bn”, the NDA said, including the construction of £600m of storage tanks for the highly-radioactive “liquor” that is produced by reprocessing.

“It would be very expensive to carry on much longer,” said Bill Hamilton, head of stakeholder relations at the NDA. “If there was a market out there, there would be a reason to invest, but there is no major appetite.”

As well as the high cost, reprocessing is controversial because the plutonium produced could be used to make nuclear weapons, and the waste is much more radioactive than spent fuel.

Mike Graham, national secretary of Prospect, the union that represents many Sellafield workers, said: “Today’s announcement comes as a great disappointment to our members at Thorp who believe firmly that the plant has a future and have been actively campaigning for new reprocessing contracts.”

The government’s plan to build new nuclear reactors in the UK does not include reprocessing of spent fuel. It proposes to create an underground repository for the permanent storage of existing and future nuclear waste, most likely located in Cumbria, but this is not expected to be built until 2075.

Thorp employs 800 staff out of Sellafield’s total workforce of 12,000. For a few years after reprocessing stops in 2018, several hundred staff will be needed to manage the winding up of the plant. The NDA said it was confident that “the majority of the workforce can be redeployed elsewhere” at Sellafield.

Last year the NDA decided to close Sellafield’s Mox plant, which recycles plutonium into mixed oxide fuel, following doubts over orders from Japan after the Fukushima nuclear crisis.

Mr Hamilton said that reprocessing in the UK could be revived in the future, but would require a more modern plant. “Thorp’s not the answer, it has done its job, but not as well as its designers planned.”

この記事で気になったのはここ。

As well as the high cost, reprocessing is controversial because the plutonium produced could be used to make nuclear weapons, and the waste is much more radioactive than spent fuel.

高いコスト同様、再処理の問題はプルトニウムが核兵器に使われてしまう可能性と廃棄物の放射能が使用済燃料より強くなってしまうこと。

Accidents 1980's

1980
15 April

LA HAGUE, FRANCE - France came very close to a major nuclear accident when fire caused a breakdown of the cooling system at the waste dump and reprocessing plant at La Hague. The fire destroyed the transformer leaving the emergency generators without current. Electricity is vital for the pumps which work non-stop cooling the highly radioactive waste in the giant storage tanks. With the cooling system not working, the tanks began to boil. It was estimated that it would only take three hours before the water would evaporate and the waste would be spread into the atmosphere. With the failure of the electricity, everything went out of action - the instruments used for checking the Plutonium to make sure no critical mass is formed, the central instrument board, the intercom and loudspeaker system used to warn workers to evacuate. All areas of the plant were contaminated. It will take several months to repair the electrical installations. Authorities have tried to deny that any failure occurred. (W.I.S.E. Vol.2 No.4 p.15)

1980年4月15日仏ラ・ハーグ再処理工場で火事。変圧器に引火。稼動中の発電機以外すべて破壊。使用済み燃料より放射性の廃液タンクの無停止冷却システムの電源が停止。廃液が沸騰する３時間前に復旧。六ヶ所再処理工場にも冷却必須のヤバい廃液タンクがある。大間のフルMOXより危険。

米ハンフォード、英セラフィールド、仏ラ・ハーグの再処理工場の話を読んでると、どこにも廃液タンクがあり、その冷却システムは絶対停止してはいけないみたい。廃液は使用済み核燃料よりも放射能が強く、沸騰し始めると人類滅亡みたいなリスクなのだとか。そんなのが六ヶ所村にもう１つ完成。

と、思ってたら東海再処理工場の廃液の方が多いのだとか。