WENRA calls for reactor pressure vessels inspection

04 September 2013

Posted By Michelle Devonshire

Reactor pressure vessels in nuclear power plants across Europe should receive a standardized review looking for manufacturing flaws, a leading organisation claims.

The Western European Nuclear Regulators Association (WENRA) has issued the recommendation to its members.

Chairman of WENRA Dr Hans Wanner said: "After discovery of indications for manufacturing flaws affecting the reactor pressure vessel at the Belgian nuclear plants Doel3 and Tihange2 in Belgium, exhaustive investigations were carried out at the affected plants."

The Belgian facilities experienced issues primarily with lower and upper ring forging on pressure vessels. This was described as a form of hydrogen flaking - a metallurgical problem that arises from the steel-making step.

WENRA considers it important for members to be aware and to make appropriate checks and measures at every plant in Europe.

Some national regulatory authorities have already chosen to demand safety reviews from the operators of nuclear plants to find any manufacturing flaws. WENRA advises adding measures on the same criteria for further safety.

Its suggestions include assistance on how to perform the review, yet the association warns that "it is up to the national nuclear safety authorities to define the necessity, testing scope, volume and non-destructive method, depending on the available information on the vessels".

If left unchecked, any flaws could prove to be dangerous over time. Equipment failure after a tsunami in 2011 at the Fukushima Daiichi nuclear plant resulted in leaks and contamination of the surrounding area.

Japan's nuclear watchdog authority also stated it still considers the plant to be unstable and it is still non-operational. A recent announcement unveiled plans worth over £300 million to build an 'ice wall' around the plant to stop the spread of radioactive water.

WENRA recommends a two-step process for improving the sector. The first step is to look into the manufacturing and review records, with a focus on service inspection and missing documentation.

Stage two, if the national authority in question deems it necessary after the first step's results, involves examination of the vessels using non-destructive testing. It is suggested these take place during scheduled testing as unscheduled shutdowns at plants are not necessary.

Dr Wanner also thanked the Belgian nuclear safety authority for their transparency throughout the investigation.

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