Sellafield clean-up will cost £34bn

And so radioactive is the site, that making it 'safe' will take 100 years

British taxpayers will have to fork out more than £30bn to clean up Sellafield, unpublicised official documents reveal. It is so contaminated that the process will take well over a century and, even then, the site will have to stay under "indefinite institutional control".

These revelations follow confirmation – in a little-noticed passage in last week's nuclear White Paper – that the controversial nuclear complex is doomed. The Government took the opportunity to make clear that the fuel from any new nuclear power stations built in Britain would not be reprocessed, thus sounding Sellafield's death knell.

For decades, the main business of the 4sq km site – which boasts that it is "the world's most complex and compact nuclear facility" – has been to reprocess highly radioactive used reactor fuel, separating plutonium and uranium from nuclear waste.

Nuclear enthusiasts have long hailed this as hi-tech recycling; the two materials can be used again to power reactors. But it has also long been the most dangerous, polluting operation in the industry and justification for it has disappeared as the world has massive uranium and plutonium supplies.

Now Sellafield's controversial Thorp reprocessing plant – which has been out of action for three years following a massive radioactive spill, disclosed by The Independent on Sunday – will formally close soon after 2011, when its contracts run out. A smaller, older plant for reprocessing fuel from Britain's first-generation reactors will follow it by 2016.

The Nuclear Decommissioning Authority and the British Nuclear Group, which own and run the site, are embarking on a clean-up which will last until 2120. If all goes well, they calculate, this will cost £41,607,803,000. They hope the remainder of their business will earn £7.9bn, leaving the taxpayer with a bill for some £34bn. If there are further accidents or delays, or if the job proves more difficult than expected, this will go even higher.

The plan envisages that high-level nuclear waste will be kept on the site for most of this century, with a "final storage facility" only becoming available in 2075, and that plutonium – a raw material for nuclear bombs – will be stored there indefinitely.