By Alex Kirby
BBC News Online environment correspondent
The UK's Atomic Energy Authority is to decommission a former nuclear research site 30 years earlier than planned.
Nature prepares to reclaim the site
The site, at Winfrith in Dorset, is due to be cleared completely by 2020, and much of the area will revert to nature.
The UKAEA says it is the government's financial rules rather than engineering that have made the speed-up possible.
It is also selling part of the Winfrith site to the national regeneration agency, English Partnerships, to try to bring more jobs and homes to the area.
The site was built in the late 1950s for research and development into generating electricity from nuclear power.
One of its nine reactors, the steam-generating heavy water reactor, used to produce enough electricity for a town the size of nearby Dorchester.
But work on the development of civil nuclear power gave way in the 1990s to research on decommissioning, after the government ended fast reactor research and accepted that the cost of nuclear liabilities was becoming prohibitive.
Now the UKAEA plans to spend £30m a year until about 2020, when the entire site will be decommissioned, thanks entirely to a change in the financial rules under which it operates.
Discounting is a technique to compare costs and benefits that occur in different time periods, and is used to convert them to "present values".
How radioactive sludge will be removed from Winfrith
Alan Neal, the site manager, told BBC News Online: "The discount rate has changed from 6% to 3.5%.
"On a site like this it costs a lot of money to stand still, with all the maintenance and security involved. The change in the rate means I can now increase the ratio of money going into actual work, not infrastructure.
"It's really incumbent on the developed world to go for non-fossil fuel technologies, with electricity consumption worldwide forecast to double by 2050.
"By showing the world there's an endgame to nuclear power stations we're keeping open the options for the next generation."
Despite the switch from pioneering research to ending the lives of their reactors, many Winfrith workers are positive about their prospects.
Andy Staples of Womad (Winfrith Operations Maintenance and Decommissioning) told BBC News Online: "In two to three years we've reduced part of the site from something that would kill you in a few hours to somewhere you can walk through in safety."
Part of the site, already designated the Winfrith Technology Centre, has now been sold to English Partnerships for £7.54m.
The tunnel into the reactor
Among about 50 companies based there is QinetiQ, described as Europe's largest science and technology organisation.
Winfrith was built on Egdon Heath, featured in many of Thomas Hardy's novels, and the UKAEA is proud that the decommissioning will benefit wildlife.
It has already sold 250 acres to the Dorset Wildlife Trust, and expects to make more available.
Chris Barrett, a landscape manager working on the restoration, told BBC News Online: "We've got Dartford warblers here, common and sand lizards, grass snakes, smooth snakes and adders - you've got to watch out for them when they're basking.
"The threat of a new reactor here has gone, and there'll obviously be a gain to several species. But there won't be any restoration of the Dorset heathland, or any addition to it.
"What there will be is more heathland corridors linking some of the existing patches, and that really will be a gain."