The report claims that the UK's largest atomic power-station, overlooking the Irish Sea, won't be completely clean until at least 2120.

Anti-Sellafield protester and Northern Ireland's South Down SDLP MP Eddie McGrady said: "The nuclear waste is a time bomb.

They are not only producing but importing the dirty stuff from the rest of the world, it is incredible."

But DUP environment minister Sammy Wilson predicted that an increase in usage of nuclear power would reduce dependence on foreign supplies of fuel from volatile and unstable parts of the world.

Reprocessing of spent nuclear fuel is expected to end by 2020 but it will take years for radioactivity levels inside unused reactors to fall to safe limits.

A spokesman for Sellafield Ltd said: "Sellafield isn't a place that can just be closed down. It is about the removal of plant and equipment from the building, it is about decontaminating and knocking them down, that takes decades.

"A lot of work has been done but with a site as complex as Sellafield that will take a long time to do carefully and safely, which is the priority and can't be compromised on."