LONDON - British Energy has found a problem with the second reactor at its Heysham-1 plant, which will need government approval to restart, but no faults have yet been found at the Hartlepool-2 reactor, a company spokeswoman said.

The nuclear power generator said earlier this month its Hartlepool-1 unit in northeast England and reactor one at Heysham-1 in northwest England had corroded wires in their boiler closure units (BCU).

Although the BCU wire at the second reactor at Heysham-1 shows no sign of corrosion, there are signs of thinning, which means the company must also get approval from the Nuclear Installations Inspectorate (NII) to restart, just as it is doing for the two units with corrosion problems.

"We've seen evidence that one of the wires on reactor two at Heysham-1 is showing signs of thinning," the spokeswoman said on Monday, adding there was still a chance that Hartlepool-2 would not need NII approval to restart.

"If there was a reactor where there were no corroded wires found... then we would be able to restart it without any recourse to the NII or without any kind of safety case," she said.

The company is already in talks with the NII on whether repairs are needed at Hartlepool-1 and Heysham-1 reactor one. But it is unclear how long the safety review and approval will take.

"It varies, it depends on the issue, on the particular station, on the individuals involved. But its not a quick process, it doesn't happen over night," the spokeswoman said.

All four of the reactors at the two similar power stations have been closed since late October after wire corrosion was found in one of them.

British Energy said at its results presentation in mid-November it expected to spend about 20 million pounds looking for corrosion in the 54 km of wire wrapped around each of the eight concrete plugs on the top of the boilers that surround the reactor cores.

Because of safety concerns over radioactive leaks, any issues with nuclear power plants are heavily scrutinised by plant operators and government regulators.

British Energy operates eight nuclear power stations built since 1965 and in recent years it has struggled with issues linked to ageing.