The Guardian, John Vidal, environment editor, Thursday October 26, 2006

The future of some of Britain's ageing nuclear power stations was yesterday thrown into doubt as government inspectors claimed cracks in the graphite cores of the oldest plants were so serious that a safety case for the stations operating much longer could not be made.

An assessment report on the Nuclear Installations Inspectorate website stated yesterday that there were expectations that most of the graphite bricks in the core of the 1976 Hinkley Point station, and its twin station, Hunterston, in Ayrshire, would crack in the near future, jeopardising the safe running of the reactors.

"British Energy predict that during the period covered [by the safety review] the majority of fuel moderator bricks will develop a single through-thickness crack from a keyway root," the report says. "Some of these may develop a second keyway root crack such that the brick may be in halves ... therefore brick cracking could affect channel straightness and the ability of the graphite core to meet its fundamental nuclear safety requirements."

It adds that the safety review "recognises that core lifetime is probably the dominant station life-limiting feature and that it is currently not possible to make a safety case for the graphite core to ...]". The date has been deleted.

The problem of the deteriorating graphite cores follows last week's disclosure by British Energy that it had encountered serious cracking problems in the boiler tubes at Hinkley. While the company declined to give a date on how long it would take to fix them, that period is thought to be at least six months. Both stations have been closed indefinitely.

According to John Large, an independent nuclear analyst, the combination of the graphite core and the boiler tube problems means it may not be economic or safe for British Energy to reopen the four reactors at the two stations. The company and the government are counting on both being granted 10-year extensions to their 30-year life-times.

Together the plants provide 6% of Britain's electricity at a time when demand is rising and when no new large-scale stations are expected to open soon.

The stations' closure is expected to seriously affect British Energy's income and electricity supplies this winter. Together the stations earn 25% of British Energy's income, roughly £2m a week. Last week the company said that only one of its eight nuclear power stations was operating fully, and its share price fell dramatically. Yesterday, four of its eight stations were working. "The old stations are the base load of the nuclear electricity system in Britain. It is very serious indeed for Britain's future electricity supplies and the company's survival," said Dr Large.

British Energy yesterday said there was no doubt that both stations would reopen, but declined to estimate when or to say when their safety operating licences would expire. "We are investigating the graphite core problem. It is a known-about phenomenon in old stations. The boiler tube problem is purely an engineering problem ... the problems are entirely solvable. This is not life-limiting."

In a separate development, the government yesterday announced that it was looking for a site for a deep bunker to store Britain's mountain of high-level nuclear waste. The environment secretary, David Miliband, said he had accepted the recommendation of the Committee on Radioactive Waste Management that the waste from Britain's nuclear reactors be buried in a deep repository.

In a Commons statement, he said the government would not impose the repository on an unwilling community, but held out the inducement of lucrative "community packages" for councils prepared to offer a suitable location. The new 470,000-cubic-metre bunker, which would take "several decades" to build, will be sunk from 200 metres to 1,000 metres underground. It is widely expected to be sited near Sellafield in Cumbria. Mr Miliband also said the government intended to build interim storage facilities to hold waste for up to 100 years while the bunker was being built.