Britain gets about a fifth of its power from nuclear energy but is committed to closing all but one of its ageing nuclear power plants over the next 20 years.

A government-commissioned energy review came out in favour of building a new generation of nuclear generators, arguing nuclear power had an important role in reducing carbon dioxide emissions and guaranteeing energy supply.

Nuclear power has also benefited from a debate over energy security after disruptions to Russian gas exports in January.

The total includes 50.8 billion pounds for decommissioning and clean-up of the 20 civil nuclear sites supervised by the NDA, 7.5 billion pounds for cleaning contaminated land and 14 billion pounds for operating sites during their remaining life.

NDA officials said the 14 billion pounds was roughly covered by income from operations and would not fall to the taxpayer.

The NDA, created in 2005, said the rise in its estimate of decommissioning costs was due to its better understanding of the costs involved in cleaning up the nuclear reprocessing plant at Sellafield in northwest England.

SUBSTANTIAL CHANGES

The NDA said it was still refining its estimate of the costs and there could still be substantial changes.

NDA Chairman Anthony Cleaver, presenting the agency's annual report, said the NDA had committed to giving the government an accurate figure for decommissioning costs by March 2008.

"It is our firm belief that over time we will bring these costs down significantly," he told a news conference.

Current plans called for the costs to be spread over up to 120 years in the case of Sellafield, he said. "Our belief is we should accelerate many of those processes. We believe that in accelerating we will also bring down the cost," he said.

The NDA's estimate does not include the cost of building an underground dump to hold Britain's growing pile of nuclear waste, although it does include waste recovery, treatment, storage and transport to the dump, NDA officials said.

The British government on Wednesday approved a recommendation that the estimated 470,000 cubic metres of waste, built up over many years, should be buried deep underground and put the NDA in charge of implementing the plan.

"The key assumption at the moment in all of our baselines is that the repository (the underground dump) opens its doors in 2040 for intermediate level waste and 2075 for high level waste and spent fuel," NDA Engineering Director Richard Waite said.

If those dates could safely be brought forward, it could save money on storing waste at sites such as Sellafield, NDA officials said.

The NDA said in its 2005/06 annual report that it had increased generation output from the ageing Magnox fleet of reactors by 12 percent from the previous year and had raised 17 percent more revenue than expected from electricity generation.