Nuclear plant is told to strengthen jellyfish defences

June's 2011's jellyfish invasion 'presented a challenge to station systems related to safety'
June's 2011's jellyfish invasion 'presented a challenge to station systems related to safety'
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THE operator of Torness nuclear power station has been ordered to make safety improvements and urged to boost its defences against jellyfish.

A new report from nuclear watchdog the Office for Nuclear Regulation (ONR) has highlighted issues with checks on safety valves, concerns about radioactive waste discharge pipes, and a lack of self-closing safety doors.

The inspectors did highlight that safety overall, however, was adequate and operator EDF insisted the points raised in the reports were already being addressed.

One of the more high-profile incidents was the blockage of the coolant inlets at Torness by large numbers of jellyfish last June, which led to both reactors being shut down.

While staff took the correct action, the ONR report said it had “presented a challenge to station systems related to safety”. EDF was asked to review its safety systems, and as a result new arrangements for introducing a “heightened state of alert” for “external hazards” has been implemented.

These were used during the strong winds which battered the region in December, and are currently being monitored by the ONR.

Safety features at all nuclear power stations in the UK have come under closer scrutiny in the wake of the Fukushima disaster in Japan.

The ONR report said: “In general the arrangements made and implemented by the site in response to safety requirements were deemed to be adequate in the areas inspected.

“However, where improvements were considered necessary, satisfactory commitments to address the matters were made by the licensee.”

Other issues in the ONR report include staff at the plant failing to inspect a safety relief valve on a nitrogen test rig when they should have done. Both the ONR and EDF said that the problem had since been addressed.

EDF was also criticised for producing a draft report that “did not adequately address the issues” raised by the ONR about the condition of pipes for discharging radioactive tritium, after a small leak from one of the pipes was reported last February.

EDF Energy insisted that all its plants, including Torness, had good safety records.

“This regulator’s report was part of our ongoing dialogue with [the] ONR, whose job it is to scrutinise our operations in detail,” said a company spokeswoman.

“We welcome their input and use it to learn and improve.”

The spokeswoman added: “Both units at Torness Power Station were manually shut down in June as a precautionary measure in line with normal operating procedures. The shut down cooling systems performed in a satisfactory manner and at no point was there a risk to our ability to cool the reactors or nuclear safety in general.”

Addressing the other concerns, she said an operator failed to inspect one valve during a routine inspection which had no implications for safety. However, EDF had agreed to draw up procedures to ensure it did not happen again.

The firm has also agreed to ensure all “station hazard barrier” doors are designed to close automatically.

She added: “In February, during routine sampling, we detected abnormal readings in water in one borehole. The readings were extremely low – one would have to drink one tonne of the fluid found to receive a dose equal to 30 minutes’ flying time in an aeroplane. The drip was fixed immediately and we carried out a review of the entire pipe. The ONR has since asked for a more detailed report on this, which we have provided.”