Lang Banks of Friends of the Earth: "There must be changes to the Scottish nuclear industry"

Strong winds twice knocked out power lines and forced staff to close down the advanced gas-cooled reactors at the Hunterston B power station on Sunday after cooling systems failed.

The Ayrshire plant, which began generating electricity in 1976, remains out of action and a spokesman for the Nuclear Installations Inspectorate (NII) said a full-scale investigation is under way.

The incident began when the storms destroyed power supplies at 2300 GMT on 26 December.

Emergency generators switched on automatically to prevent the cores overheating but, according to reports in The Mirror newspaper, not enough staff were on duty to reset them before power went down for a second time at 1145 GMT on Sunday.

Specialist staff were called from their homes to deal with the incident and worked for at least four hours to manually reset the safety systems.

The cooling systems of a nuclear reactor prevent the core from reaching a "critical" state.

A core at such a state can cause a major disaster such as that at Chernobyl.

Nuclear engineer John Large: "These things should work like clockwork"

Emergency services were called to the plant on the Scottish west coast, south of Largs, as part of safety procedures for a "grade two" alert. The most serious incidents are classified as grade seven.

Lang Banks of Scottish Friends of the Earth, who lives two miles away from the plant, demanded action from the nuclear industry.

"The same thing happened at Dounreay," he said. "The management have to be questioning what they are doing with nuclear power stations in Scotland.

"For the coolant systems not to come on and the back-up systems to fail is an extremely serious incident."

John Large, a nuclear engineer, told BBC News that the incident may have been triggered by human error, saying that the Hunterston reactor is designed to run without operator intervention for 30 minutes.

But British Energy, operators of the plant, stressed that no radiation was released and there had been no danger to staff or the public.

Spokeswoman Ann Campbell said: "This was a consequence of very severe weather and the station decided to declare an on-site emergency because this was the best way to deal with the problem".

Ms Campbell said that Hunterston B would wait for clearance from the NII before restarting the reactors.