Plans to revive nuclear power are stirring on both sides of the Atlantic. In Britain, Tony Blair's government has been making upbeat noises about the need to replace existing nuclear power plants to fend off both national dependence on foreign sources of energy and global warming.

In the United States, however, President George Bush is said to be contemplating a step that will revive public concern about the link between nuclear energy and nuclear weapons — and could ultimately set back any prospect of reviving the former.

When it is released next week, Bush's 2007 budget proposal is expected to include a provision that would start to revive nuclear-fuel reprocessing. That would end a three-decade-old strategy in the United States that has sought to sever the connection between nuclear power and nuclear weapons.

Nuclear-fuel reprocessing aims to reduce the volume of spent nuclear fuel that has to be disposed of safely by recycling it for use in new types of nuclear reactor. But the recycling involves separating components that can readily be used to build nuclear weapons.

Of the countries with significant nuclear power capacity, the United States and Germany abandoned reprocessing early on, and Britain, having ditched the fast-reactor design that would burn the recycled fuel, looks set to follow suit. Japan is trying to build a reprocessing plant, but only France has stuck resolutely with fuel recycling. An official study commissioned by the French prime minister found recycling to be costly, however, and France has not yet managed to ‘close’ its fuel cycle by finding a place to put its waste.

The United States had (and has) ultimate responsibility for the nuclear-fuel cycle at plants that have been built by US contractors around the world. It abandoned reprocessing in a bid not just to lead by example, but to prevent a situation whereby countries that operate US reactor technology might obtain access to plutonium production lines.

The decision to abandon recycling sought to put the nuclear weapons genie back in the bottle in arguments over nuclear energy, in the United States at least. Bush's plan would release it again — and galvanize US opposition to nuclear power. Its adoption by Congress would effectively concede that US plans for the safe long-term disposal of nuclear waste at Yucca Mountain, Nevada, are not going to solve the waste problem.

The plan to revive the nuclear-fuel cycle comes at a peculiar time. The Pittsburgh-based company Westinghouse, which constructed most of these US-built plants, is being purchased by Toshiba for $5 billion. This suggests that, in the eyes of some seasoned Japanese business executives at least, general global prospects for nuclear power are improving.

The case for a nuclear power revival has ben well rehearsed. The global panic induced by the 1979 performances of Jane Fonda and Michael Douglas in The China Syndrome — and inflamed by the real-life version released at Three Mile Island in Pennsylvania 11 days later — is beginning to die down. European memories of the 1986 Chernobyl accident are also fading.

The case for nuclear energy now rests on the supposition that it is less bad than the alternatives.

Perhaps more to the point, the case now rests not on the specious grounds that nuclear energy will be immensely cheap, but on the rather more solid supposition that it is less bad than the alternatives. With coal causing global warming, oil and gas equated with dangerous energy dependency on outside suppliers, and renewable sources unable to produce the gigawattage that we apparently require, nuclear power is firmly back in the picture.

Yet the waste issue will need to be addressed before any ground is broken for a new nuclear power station in either Britain or America. Britain abandoned plans to build an underground waste repository in the north of England in 1997, and a report due this summer from a consultative panel, the Committee on Radioactive Waste Management, is only the first step in the search for a new approach. In the United States, the outlook for the Yucca Mountain project is uncertain, and the proposed repository there is, in any case, too small to meet forecast needs.

It may be that the Bush proposal reflects the administration's frustration over continued opposition to the Yucca Mountain repository. But, in the end, the only environmentally or financially viable path to nuclear power generation involves wrestling with the murky details of long-term waste disposal. Fuel recycling may look exciting on paper; in practice, it is part of the problem, not the solution.