A Newsnight investigation suggests that UK government plans to build a new generation of nuclear power stations to fill the energy gap by 2020 are wildly optimistic.
The British nuclear regulator has told Newsnight that he would not hesitate to halt construction if problems emerged and that no British nuclear power station had ever been built on time.
The first of the new generation of reactors in Britain will be at Hinkley Point in Somerset, and will be a replica of the new Evolutionary Power Reactor (EPR) reactor currently being built in Finland by the French company, Areva.
The Finnish EPR at Olkiluoto was supposed to be the first "third generation" reactor - safe, affordable, and designed for mass production.
The reactor is three years behind schedule and billions of pounds over budget after more than 3,000 mistakes were made by the builders.
The Finnish nuclear regulator has also halted construction on at least a dozen occasions due to safety concerns.
British regulator, Kevin Allars of the Nuclear Installations Inspectorate (NII), told Newsnight that he will be every bit as tough as his Finnish equivalent.
Earlier this year, EDF announced that by 2017 Britons would be cooking their Christmas dinners with electricity generated by a new EPR nuclear power station at Hinkley Point, and that come 2020 four reactors would be operating in time to fill any energy gap.
Regulator on UK track record delivering new reactors on schedule
The Energy Secretary Ed Miliband this month issued a provisional go-ahead for ten new nuclear power stations, including Hinkley Point. EDF and Areva have until June 2011 to produce a design which will satisfy the British regulators.
But Finland's regulator, Petteri Tiippana says that the current design for the reactor at Olkiluoto is not safe because emergency circuits are not independent of normal control systems:
"If they aren't independent then the failure in the normal systems can cause a failure in the safety systems," he said.
Areva have promised to submit an improved design to the British and Finnish authorities, after which planning permission to build at each of the British sites must be applied for which is likely to take at least another year - taking us to the middle of 2012.
EDF will then have just five years to build the Hinkley Point reactor if we are to be able use its power to cook Christmas dinners in 2017.
The last reactor built in Britain, Sizewell B in Suffolk, was completed in 1995 and took some eight years to build.
Five years have passed since Areva began work on the Finnish reactor and it will take at least another three years to finish the job - eight years in total.
Ed Miliband wants new power stations in place by 2017-18
Newsnight asked the man in charge of regulating new nuclear stations here, Kevin Allars of the NII, if any nuclear power station had every been delivered on time in the UK.
"No," was his response.
The Finnish regulator, Mr Tiippana, says it is difficult to deliver these projects on schedule because builders are not used to working to the exacting standards required on nuclear construction sites since so few new reactors have been built in recent years.
Mr Tiippana says that if construction workers do not have the right concrete to build the foundations they will use whatever is to hand, if it is awkward to put a radiation sensor where it should be they will be tempted to put it somewhere else, if it is easier to drill holes in the radiation containment vessel they will do it.
All these mistakes occurred in the construction of the Finnish reactor, just a few of the 3,000 errors detected so far. Correcting them has caused months of delays.
"When they encounter a problem on site they usually follow their previous experience" says Mr Tiippana, "this is how we did it on a coal power plant and that just doesn't work on a nuclear construction project".
Areva was so confident about the EPR that they agreed to build the reactor in Finland with a fixed delivery date of May 2009, and for a fixed price.
The earliest the reactor is now expected to come on line is 2012 and it is 3bn euros (£2.71bn) over budget.
Areva have threatened to abandon the reactor partially built unless they are given more cash.
Building nuclear power stations to order may not prove to be as easy as Ed Miliband might think.
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