For supporters of nuclear power, a new generation of reactors is critical to meeting Britain’s ambitious climate-change targets. Nuclear output of ten gigawatts - a sixth of Britain’s peak needs – will be lost by 2023, and carbon emissions will rise if this gap is filled with fossil fuels.

Environmental campaigners, however, remain sceptical, arguing that nuclear’s contribution to greenhouse-gas reductions is exaggerated and outweighed by the intractable problem of waste.

The pro-nuclear argument focuses on electricity, 20 per cent of which comes from nuclear plants that are nearing the end of their lives. Though the goal is for renewables to provide 20 per cent of electricity by 2020, that means net emissions would stand still if no replacements were built.

Opponents counter that electricity accounts for only a third of Britain’s total energy use and that nuclear will not cut carbon output from heating and transport. They often cite the Sustainable Development Commission’s estimate that new nuclear stations would reduce total emissions by only 4 per cent.

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However, even if one accepts the 4 per cent figure – and the nuclear White Paper puts it higher, at 5 to 13 per cent – it is not trivial. It is roughly equivalent to taking one in three cars off the road. Were such a reduction suggested for a nonnuclear technology, the greens would be all over it.

The criticism would be justified if ministers were proposing nuclear power as the sole solution to low-carbon energy, but they are quite clear that renewables are needed, too. The Government also makes valid points about energy security, as nuclear power is not reliant on imports from politically unstable regions. Most uranium comes from Australia.

The antinuclear lobby is right that the 2050 target of 60 per cent carbon cuts could be met without atomic plants, but only if carbon capture and storage (CCS) allows emissions from fossil fuels to be reduced by 90 per cent.

Although that is possible, no cost-effective power station with CCS has yet been built. Everybody hopes that this promising technology comes of age, but the Government is wise not to count on it. The best argument against nuclear plants remains their waste, which is radioactive for thousands of years. Those who cite it, though, bring to mind the Irishman’s celebrated reply when asked for directions to Trafalgar Square: “I wouldn’t start from here.”

If Britain had never had nuclear power, this issue would make the case against it compelling. Yet the country already has enough to fill five Albert Halls, and a deep underground facility to store it must be built, whether new plants are ordered or not.

As the latest reactors produce about a tenth of the waste churned out by their predecessors, the solution is quite simple. We will just have to dig a slightly bigger hole that will have to be dug anyway.

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