Revealed: faulty nuclear reactor was allowed to operate without safety alarm

Britain's nuclear watchdog last month allowed a faulty nuclear reactor to start up even though it had not been fitted with an important safety system, startling internal documents seen by
The Independent on Sunday reveal.

The documents also show that the Nuclear Installation Inspectorate (NII) judged that the reactor, at Oldbury nuclear power station in Gloucestershire, was not safe enough to operate for the next 18 months, but allowed it to go onstream until November anyway.

The revelations - described as "deeply alarming" by top nuclear expert John Large yesterday - are bound to fuel concern at a time when ministers are encouraging the building of a new generation of reactors.

The heavily censored documents - released under the provisions of the Freedom of Information Act to the Stop Oldbury campaign - come from an investigation into the safety of reactor 2 at the power station. They reveal a one-in-1,000 risk of a fire in the highly radioactive nuclear fuel, a figure that Dr Large regards as "unacceptably high".

They show that the NII pressed for the installation of a safety system, called "a failed fuel trip system", which would automatically shut down the reactor if such a fire broke out. But it accepted the response of the power station's operator, the British Nuclear Group, that "it would be disproportionate to further delay the return to service of the reactor" while it was fitted.

The NII also cast doubt on the company's ability to cope with exceptional circumstances. But the watchdog still allowed the reactor to start up last month and operate until November. In the event, within two weeks an unrelated fire broke out in a non-nuclear part of the plant, and the power station had to be shut down indefinitely.