They have also suspended refuelling at their Calder Hall plant in Cumbria, which uses the same refuelling system as Chapelcross, while moving to reassure the public that the incident was a "low level" nuclear incident.

BBC: Nuclear plant accident probed

When the oldest of these, Calder Hall at Sellafield in Cumbria, was opened by the queen in 1956, the government hoped that the electricity produced by Britain's first nuclear power station would be so cheap that it would be hardly worth metering and charging for.

ECONOMIST: Nuclear energy