It will cost at least £73 billion to decommission the UK's first-generation civil nuclear sites and run the remaining operating ones, MPs have claimed.
The figure is an increase of 30 per cent since 2003 and the Public Accounts Committee (PAC) claims there is no guarantee that this figure will not be "significantly upped".
In January 2008 the government announced it would allow energy companies the option of investing in new nuclear power stations.
Operators will be expected to meet the full cost of decommissioning new facilities and their full share of waste management costs.
But PAC chairman Edward Leigh said today that the Department for Business, Enterprise and Regulatory Reform (BERR) had not been able to provide the committee with "complete assurance that the costs of decommissioning new nuclear power stations will not fall back on future taxpayers".
The committee found that while the Nuclear Decommissioning Authority (NDA) has established decommissioning plans for clearing individual sites, there is considerable uncertainty over the costs of decommissioning.
It claims that the authority is dealing with a legacy of deferred decision making going back over 50 years of the UK's nuclear power programme.
Some uncertainty in the cost estimates is, the MPs said, inevitable, but some of the escalating cost estimates should have been avoidable, including extra costs imposed by short-term changes to the decommissioning programme and the scale of site support costs.
The PAC also claims that the NDA's work has been hampered by uncertainty in the level of commercial income earned from ageing and unreliable facilities, and by emerging priorities at Sellafield.
It recommends that BERR should ensure there are robust arrangements to ensure that operators of new stations make adequate provision.
Before giving the go-ahead to new sites, the PAC advises that BERR should be confident operators can make arrangements to meet all future decommissioning costs.