The French and Chinese companies that are to build the £18bn Hinkley Point C nuclear power station will have to pay up to £7.2bn to dismantle and clean it up.

Documents published yesterday reveal for the first time how much the developers, EDF and China General Nuclear Power Group (CGN), will have to pay to decommission the plant, beginning in 2083.



The new reactors in Somerset will be unique in British nuclear history, as they are the first for which the operator will have to pay to make good the site afterwards.



“Waste transfer contracts signed today mean that, for the first time in the UK, the full costs of decommissioning and waste management associated with the new power station are set aside during generation and are included in the price of the electricity,” EDF said in a statement.



Decommissioning costs ate up around half the budget for the now-disbanded department of energy and climate change, after the liabilities for cleaning up old nuclear plants were effectively nationalised in 2004 and 2005 when two companies faced financial problems.



The Hinkley Point C decommissioning costs are estimated at £5.9bn to £7.2bn, with the dismantling of the plant expected to begin in 2083. The government, EDF and CGN anticipate the winding up of the new reactors will continue well into the 22nd century. The plant is expected to be fully decommissioned “from 2138” when the final spent fuel is disposed of.



Experts said the cost estimate was likely to be on the low side. “The reality in terms of decommissioning is that it always costs more than people say,” said Dr Paul Dorfman, of the Energy Institute at University College London.



He claimed that the precedent of the government taking ownership of the liabilities of British Nuclear Fuels Limited and British Energy more than a decade ago showed that the government would be forced to shoulder the costs if Hinkley’s developers had a shortfall.

The body charged with dismantling 17 of Britain’s old nuclear power plants puts the cost of cleanup at £117bn over 100 years in its latest annual report, more than twice the cost estimated a decade ago. A large proportion of the cost is due to the complexity of Sellafield.

The business department also admitted that large scale solar power and onshore windfarms could produce electricity for less than the price agreed for Hinkley, as the National Audit Office said in the summer.



But officials suggested there would be additional costs to the renewable alternatives. “There would be significant upgrades to the grid required (such as connection and planning costs) as well as increased costs to keep the system in balance,” said the ‘Value for money assessment’.



Greenpeace UK executive director, John Sauven, said: “We now have it straight from the horse’s mouth. Increasingly cheaper renewable energy sources do indeed offer better value for money to British bill-payers than Hinkley.



“The government tries to obfuscate the advantages of solar and wind by throwing in extra costs for grid upgrades and balancing the energy system. But there’s no evidence anywhere in the documents to back up their assumptions.”