Decommissioning of the Sellafield nuclear plant has begun - a process which will eventually result in the loss of thousands of jobs.
The NDA has now assumed responsibility for Sellafield
The Nuclear Decommissioning Authority (NDA) officially assumed responsibility for the clean-up of the nuclear reprocessing complex on 1 April.
According to the NDA, the process could take up to 100 years, but heavy job losses are expected within 10 years.
Trade union Amicus says permanent staff posts are likely to be cut by 8,000.
The current figure of 12,000 employees could be reduced to 4,000 by 2011, said the union.
From 1 April, the two organisations that have historically owned and operated the site - British Nuclear Fuels (BNFL) and the UK Atomic Energy Authority (UKAEA) - will effectively become contractors for the NDA, the new owners.
Currently-employed staff will remain on the payroll of the British Nuclear Group. The decommissioning process, which is being funded by the government, is expected to cost the taxpayer £48bn.
Sir Anthony Cleaver, chairman of the NDA, said it took its responsibility to the local community very seriously.
He said: "If we look at the current plans there will be a dramatic reduction in jobs, but that's a long way ahead.
"We have a responsibility to look at the local economic and social impact of anything we organise. We will look at the amount of jobs that may be lost and work with the local community to see how we can best address that issue.
"I can understand the concerns of employees but, having said that, BNFL has the contract for the next two, maybe three or four years, which means there should not be a major change in the short term."
The trade union Amicus has called for permanent staff to be retrained to carry out the decommissioning work and plans to oppose the outsourcing of any core work.