Sellafield calls off radioactivity alert

Sellafield, the largest nuclear site in Europe, declared an alert on Friday after discovering higher than usual levels of radioactivity, but later called it off, saying naturally occurring radon gas had triggered the alarm.

The fuel reprocessing plant in northwest England, the site of Britain's worst nuclear accident in 1957 and once the producer of plutonium for nuclear bombs, told non-essential staff to stay away after the abnormality was detected overnight.

The plant's operating company said there was nothing wrong with its operations, but for several hours the cause of the higher reading at an air monitor near a perimeter fence was unclear, raising fears of a radioactive leak.

Before midday, the operating company, Sellafield Ltd, said it had found that radon, a naturally occurring radioactive gas that comes from rocks and soil, was the cause.

"This is a very rare occurrence and the alert is over. Everything will be back to normal on Saturday," said a spokesman from the Nuclear Decommissioning Authority (NDA), the public sector body that owns the site.

The ageing facility, by Britain's picturesque Lake District on the coast of the Irish Sea in northwest England, continued to operate normally during the morning and the operator and the government said there was no risk to the public.

It was the first time local inhabitants could recall staff being sent home.

"It worries everyone but we try not to panic," said Robyn Turner, 42, who works in a supermarket in the nearby coastal village of Seascale. "You just have to trust that they know what they're doing."

Managers at Sellafield, a large, fenced-off site of grey buildings, industrial cylinders and cooling towers about 300 miles northwest of London, said the decision to keep staff at home was conservative but "prudent".