At last we know the score, officially, on nuclear power policy. Or do we?

We do know that the climate has changed in the last five years, so the government is now openly supportive of nuclear new-build. Supportive, that is, without actually offering overt financial support.

That said, the juicy prospect of a government-guaranteed and steadily rising carbon price should simplify the sums for prospective investors (in renewables as well as nukes).

It’s unclear, though, how far the taxpayer will be the unpaid insurer of last resort if anything goes wrong. History does tell us, after all, that something might. So goodness knows what can justify the government’s apparent confidence that there’ll be neither accidents nor bankruptcies. Or its extraordinary insouciance about something that is actually inevitable. Namely, that a batch of new nuclear power stations will mean, eventually, more radioactive waste for long-term ‘disposal’.

The official line on this boils down to: (i) we’ve already got a waste problem so the government will be building a bunker anyway (guesstimated cost £20 billion); (ii) the industry will pay to lease space in it, so it’s not a hidden subsidy; (iii) the new ‘third generation’ reactors will actually produce much less radioactive waste than the old ones; and (iv) if need be, the industry can just pay for an extension to the bunker.

Sorry, but which bunker is this, precisely? This is tantamount to sharing out slices of pie in the sky (or its indigestible equivalent). It was only last week that Defra announced the results of a consultation favouring geological disposal, which in practice means entombing high-level nuclear waste several hundred metres underground, having first encased it in glass and put it in thick metal canisters. At the moment, this stuff is just piling up in ‘intermediate storage’ at Sellafield. We’re promised a White Paper later this year – but so far we haven’t even formally begun the process of choosing a final burial site.

It’s the kind of decision politicians don’t exactly relish. Even the French – who, you’ll have noticed, are getting great press at present as the shining lights of the nuclear power world – are still havering between granite or clay as the geology of choice, and they reckon it’ll be 20 years from deciding, to accepting the first consignment for storage.

The Finns are a bit further down the track – they’ve actually picked a site. But the leaders in the field are the Americans. So let’s learn from the leaders. It’s a salutary lesson.

Deep inside a geological formation in Yucca Mountain in Nevada, there’s a repository already holding intermediate-level nuclear waste from the military programme. The federal government’s plan – refined over decades of studies – is to open a further facility there, for long-term storage of high-level waste from nuclear power plants. Right now there’s a fair old political battle on about getting a license for this from the US nuclear regulator. Congress is far more hostile than in 2002, when it approved the project in broad terms. Nevada senator Harry Reid, a firm opponent, is now Senate majority leader, and neither of the leading Democratic presidential candidates is prepared to give their backing.

In an earlier age of innocence (or complicity?), however, the US government had actually promised to have somewhere ready to take spent nuclear fuel by 1998. Yes, 1998. Since then, the US taxpayer has been racking up a hefty liability to the nuclear power plant operators, whose payments into a special fund entitle them to storage space.

Wait – it gets worse. The “best possible construction schedule” at Yucca Mountain envisages a repository opening in 2017 – if all the permissions go through smoothly and there are no “litigation-related delays”. Some hope. But, almost unbelievably, the government is locked in to delivering this ‘best possible’ schedule, or paying out truly huge penalties. Here’s Ward Sproat, testifying to Congress as director of the Office of Civilian Radioactive Waste Management: “For each year beyond 2017 that the repository’s opening is delayed, the Department (of Energy) estimates that US taxpayers’ potential liability to contract holders who have paid into the Nuclear Waste Fund will increase by approximately $500 million… in addition to the estimated current potential liability of approximately $7.0 billion due to the Department’s not beginning removal of spent nuclear fuel in 1998."

HM Treasury would never get caught out like that, now would it?