The coming nuclear crisis: All but one of Britain's ageing reactors 'will need to close in 15 years'

Nearly all the UK's stations were built in the 70s and 80s

All but one of Britain’s ageing fleet of nuclear reactors will have to be closed down within 15 years due to concerns over their economic viability or safety, a panel of experts has warned.

Only Sizewell B power station will still be operating beyond 2030, which would leave a shortfall of about 20 per cent in the UK’s power demands unless replacement nuclear reactors come on-stream in the 2020s, they said.

Britain’s existing nuclear reactors apart from Sizewell B are operating beyond their original lifetime specifications, but they are still working as safely as they were designed to be, said Professor Laurence Williams, a former chief inspector of nuclear installations.

“They have been designed safely to operate for a given period of time and the knowledge we’ve gained through the operation means we can extend that lifetime, so yes they are fit for purpose,” Professor Williams said at a press briefing in London.

However, Professor Williams warned that there will be a point when either it will be uneconomic to continue operating a given nuclear reactor, due to the additional maintenance work needed, or if it becomes too unsafe.

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“With these types of reactors there comes a time when either it becomes too expensive to do the inspections to make the modifications necessary, or we come to the view that the utility can no longer make the safety case,” Professor Williams said.

“Are we as a country allowing reactors which are potentially unsafe to continue to operate because we need them and I would say categorically ‘no’,” he said.

“They are fit for purpose because they generate 18 per cent of the UK’s electricity and they are generating that safely and economically. Who knows when the decision will be taken that these reactors are no longer fit for purpose,” he added.

Almost all of Britain’s nuclear power stations were built in either the 1970s or 1980s and most had a design life of about 25 years. However, due to a Government moratorium on building new nuclear power stations, these ageing reactors have been kept running far longer than anticipated.

“Certainly the reactors are not getting any younger and you may expect as materials age, issues may arise,” said Professor Andrew Sherry, director of the Dalton Nuclear Institute at Manchester University.

“The reactors are ageing and just as you spend money keeping your car going there will come a point where it is just not cost efficient to keep a reactor operating,” Professor Sherry said.

“It’s a balance between ‘is it economic?’ and ‘can we make the safety case?’. For some of the reactors they will be working towards 50 years, which is the current best view,” he said.

One of the main concerns is the safety of the graphite moderators within the reactors, which absorb neutrons and prevent an uncontrolled chain reaction. Scientists are concerned that the graphite becomes brittle and cracked over time.

“A single crack is no big deal. It’s a question of how many, where they are and what’s going to happen in the future,” said Professor James Marrow of Oxford University.

“It’s thinking ahead to the long term of how this situation is going to change and at what point do I need to do something. The graphite is ageing as predicted,” he said.