Scientists set to demolish Sellafield chimney on site of Britain’s worst nuclear accident

Demolition has begun on the site of Britain’s worst nuclear accident, as scientists are brought in to dismantle the infamous Sellafield chimney.

The 110-metre structure on the old Windscale plutonium-producing plant at Sellafield nuclear reprocessing site in Cumbria will finally be cleaned up more than half a century since a fire broke out in its graphite core, in late 1957. It is being dismantled after site managers said the radioactivity had now decayed to safe enough levels to work in.

Steve Slater, head of decommissioning at the site, said: “Bringing the chimney down will be a real visual demonstration of our commitment to cleaning up Sellafield.”

However, Mr Slater conceded that the task was extremely challenging. “No other structure in the world provides the same complexity in terms of radiological and conventional decommissioning constraints,” he said.

The chimney, capped after the fire, has been opened for the first time in 17 years. The first phase of the dismantlement will strip the filters, a task made extremely difficult by the fact that they trapped radiation which was released when the reactor overheated.

There is about 500 tons of structural materials including steelwork, bricks and masonry in the filter sector of the chimney alone – while more than 5,000 tons of material will need to be recovered during the full demolition of the chimney.

The reactor pile was damaged beyond repair by the fire, which raged for many hours. Most of the radionuclides released were trapped by the chimney filters, but contamination did escape into the atmosphere.