LONDON/PARIS (Reuters) - German utility E.ON's breakup has led to worries that funds set aside for decommissioning reactors will not suffice, but globally the cost of unwinding nuclear is uncertain as estimates range widely.
As ageing first-generation reactors close, the true cost of decommissioning will be crucial for the future of the nuclear industry, already ailing following the 2011 Fukushima disaster and competition from cheap shale gas, falling oil prices and a flood of renewable energy from wind and solar.
The International Energy Agency (IEA) said late last year that almost 200 of the 434 reactors in operation around the globe would be retired by 2040, and estimated the cost of decommissioning them at more than $100 billion.
But many experts view this figure as way too low, because it does not include the cost of nuclear waste disposal and long-term storage and because decommissioning costs - often a decade or more away - vary hugely per reactor and by country.
"Half a billion dollars per reactor for decommissioning is no doubt vastly underestimated," said Mycle Schneider, a Paris-based nuclear energy consultant.
The IEA's head of power generation analysis, Marco Baroni, said that even excluding waste disposal costs, the $100 billion estimate was indicative, and that the final cost could be as much as twice as high. He added that decommissioning costs per reactor can vary by a factor of four.
Decommissioning costs vary according to reactor type and size, location, the proximity and availability of disposal facilities, the intended future use of the site, and the condition of the reactor at the time of decommissioning.
Although technology used for decommissioning might gradually become cheaper, the cost of final waste depositories is largely unknown and costs might spiral over time. Reactor lifespans are measured in decades, which means financing costs and provisions depend strongly on unpredictable interest rate levels.
"The IEA estimate is, without question, just a figure drawn out of the air. The reality is, the costs are quite phenomenal," said Paul Dorfman, honorary senior research associate at the Energy Institute, University College London.
The U.S. Nuclear Regulatory Commission estimates that the cost of decommissioning in the United States - which has some 100 reactors - ranges from $300 million to $400 million per reactor, but some reactors might cost much more.
France's top public auditor and the nuclear safety authority estimate the country's decommissioning costs at between 28 billion and 32 billion euros ($32-37 billion).
German utilities - such as E.ON, which last month said it would split in two, spinning off power plants to focus on renewable energy and power grids - have put aside 36 billion euros..
Britain's bill for decommissioning and waste disposal is now estimated at 110 billion pounds ($167 billion) over the next 100 years, double the 50 billion pound estimate made 10 years ago.
Japanese government estimates put the decommissioning cost of the country's 48 reactors at around $30 billion, but this is seen as conservative. Russia has 33 reactors and costs are seen ranging from $500 million to $1 billion per reactor.
The IEA's Baroni said the issue was not the exact cost per reactor.
"What matters is whether enough funds have been set aside to provide for it," he said.