The last of British Energy's four nuclear reactors to return from lengthy repairs that began in late 2007 was restarted this morning, the company's new owner said.

The 575-megawatt reactor two at the Heysham-1 power station in northwest England has resumed electricity production for the first time in 17 months, EDF Energy said, six weeks after reactor one at the plant was restarted.

The two units at Heysham, together with two other reactors at Hartlepool in northeast England, were shut in October 2007 after an inspection revealed some boiler closure unit (BCU) wires had corroded.

"Now the BCU programme is complete, reactor 2 is supplying power to the grid and will gradually be brought back to full power over the coming days," Gwen Parry-Jones, station director at Heysham said.

"The start-up is not routine as the unit has been out of service for almost one and a half years and a robust recommissioning programme was developed to return the unit to full power."

The other three reactors restarted after lengthy shutdowns all had to stop again just days after coming back into service.

Hartlepool 1 had to shut for a few days just two days after coming back from its 14-month outage in late January, Hartlepool 2 closed for minor work shortly after restarting in mid February and Heysham 1-1 stopped for 10 days in early February.

During the lengthy outages British Energy also brought forward maintenance work at both stations, EDF said.

British Energy was bought by France's EDF in January 2009 and plans to build four new reactors in Britain with the first operational by the end of 2017.