A British company claims to have found the "holy grail" of the nuclear energy industry - a solution to the problem of radioactive waste disposal.
Amec, the London company that cleaned up Ground Zero in New York and rebuilt the Pentagon after the September 11 attacks, says that its latest process will enable nuclear waste to be stored safely for 200,000 years - longer than the radioactivity will last.
The company says that the method could transform the nuclear energy industry and offer a viable alternative to fossil fuels.
The technique, called geomelting, has been tested successfully by the American government, which is building a $53 million (£30 million) pilot plant in Washington state. It intends to use the method on 300,000 gallons of liquid waste from atom bomb tests in the 1940s.
Amec has already held talks with British Nuclear Fuels, the state-owned nuclear energy company that owns the reprocessing plant at Sellafield in Cumbria and employs 23,000 people in 16 countries. It plans to send a team to America to look at Amec's site in the next few months.
The Department of Trade and Industry will also study the process. Earlier this month an official said that a huge expansion of the nuclear power industry - including the construction of 45 new reactors - was essential if the Government were to meet its Kyoto target of cutting "greenhouse gases". Many environmentalists, including James Lovelock, have embraced nuclear power because it does not generate greenhouse gases.
The Amec process involves mixing nuclear waste with soil or other "glass-formers" in large, lined metal tanks. The mix - 20 per cent waste and 80 per cent soil - is heated through two graphite electrodes at temperatures of up to 3,000C. Gases, mostly carbon dioxide and traces of hydrocarbons, are drawn off and treated separately. The molten substance is then allowed to cool and forms a large glass block that is harder than concrete.
The process, known as vitrification, was devised by the Battelle research institute in Ohio, which also invented the photocopier and the compact disc.
Amec, which has worldwide interests in gas, oil, mining and forestry - and a turnover of £4.7 billion last year - bought the technology from Battelle. It has an international licence for the process.
British Nuclear Fuels stores much of its waste in concrete, which lasts up to 200 years. This has prompted widespread concern that radioactive material will leak into the water supply and pose a serious threat to public health and the environment. Some nuclear waste at Sellafield is already vitrified by British Nuclear Fuels, using a "continuous melting" method that stores the waste in 6ft containers resembling milk churns. The churns are sealed remotely and stored above ground. Last year 341 containers were filled with vitrified waste.
The vitrification does not, however, last as long as the radioactivity and "a certain amount of repackaging" is necessary, a spokesman said.
Amec said that its method produced a higher quality and longer-lasting glass than British Nuclear Fuel's at three-quarters of the cost.
The new form of vitrified waste is more durable than British Nuclear Fuel's because it contains fewer chemicals. Don Fraser, the global director of Amec's GeoMelt projects, said: "The nuclear industry has an image problem and most of the public concern is over the problem of dealing with radioactive waste. We believe that GeoMelt solves that problem and could transform the energy industry. It is more effective than any other process that has been developed so far."
Mr Fraser said that the glass would last for "geological times" and almost all the radiocative particles in it "would decay to non-radioactive elements or compounds long before the glass corrodes away to nothing". It would, he said, "pose no danger to the public or whoever else is living there in thousands of years' time".
A spokesman for British Nuclear Fuels said: "We will have a good look at this process. "We know that nuclear plants work and are safe, but what to do about nuclear waste remains the biggest issue facing our industry. We are always looking for innovative solutions for cleaning up and reducing nuclear waste and we will look seriously to see if geomelting can play a role in that."
However, Jean McSorley, a nuclear energy specialist at Greenpeace, the environmental campaign group, said that geomelting was not a solution to the problem of nuclear waste, but might be a step in the process of managing it.
"There is, as yet, no environmentally acceptable solution to the problem of nuclear waste," she said.
"We have always encouraged vitrification, but only time will tell whether this is more effective than existing methods." Last week Adrian Gault, the strategic development director at the Department of Trade and Industry's energy strategy unit, said that nuclear power would have to provide half of Britain's electricity needs if the Government were to reduce carbon dioxide emissions by 60 per cent by 2050.
Tony Blair, the Prime Minister, described climate change as "the biggest challenge facing the planet" and said it would be high on the agenda when Britain takes over presidency of the G8 summit and the European Union next year.
Nuclear power provides a fifth of Britain's electricity, but the nuclear plants - which do not produce carbon dioxide - are due to be closed gradually from 2008, and there are no plans to replace them.