It has been revealed that it will take more than 100 years before the toxic nuclear site in Sellafield is safe.
A report from Westminster's Public Accounts Committee says the UK's largest atomic power station will not be completely clean until 2120.
The South Down SDLP MP, Eddie McGrady, described the nuclear waste as a time bomb waiting to happen. 'They are not only producing but importing the dirty stuff from the rest of the world, it is incredible,' he said.
The report warned that the cost of decommissioning all nuclear plants was likely to rise because successive governments and the nuclear industry found it easy to push costs on to future taxpayers.
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. The buildings will have to be demolished and the site readied for possible redevelopment.
Martin Forwood, campaign organiser at lobby group Cumbrians Opposed to a Radioactive Environment, said he accepted there would be a lengthy delay.
'I suspect that they will decommission power stations much quicker than under the original plan,' he said. 'The French or the Japanese think they can do it in 40-50 years.'
A spokesman for the British Nuclear Fuels subsidiary Sellafield Ltd admitted the clean-up operation would take decades.
'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.'
He said it would cost £73bn to decommission over the next 112 years. The PAC report said estimates of decommissioning costs across the UK had risen by 41%.