EDF extends outages at British nuclear plant where cracks were found

By Susanna Twidale

LONDON (Reuters) - EDF Energy has extended by several weeks outages at its Hunterston nuclear plant in Britain, while the company seeks to prove it is safe for the more than 40-year-old plant to restart after cracks were discovered this year.

Reactors 3 and 4 have been offline since March and October respectively after cracks were found during routine inspections at the plant, which can produce enough electricity to power more than 1.7 million homes.

Before EDF is allowed to restart the reactors it must show they can operate safely. It must present safety cases to Britain's nuclear regulator, the Office for Nuclear Regulation.

The safety cases "must demonstrate that, for the next period of operation, the reactor will operate and shutdown safely during normal operation and during a highly unlikely earthquake scenario", a spokeswoman for EDF Energy, owned by French energy group EDF, said by via email.

Hunterston B-7 (reactor 3) is now expected to return to service on April 30 while Hunterston B-8 (reactor 4) is expected to be back online from March 31, EDF Energy said on its website.

The spokeswoman said the outages had been extended to allow for the assessment of the new seismic analysis and further modelling work required to underpin safety cases.

A safety case has already been submitted to the ONR for reactor 4 while the company is preparing to submit a safety case for reactor 3.

"It is not possible for us to confirm with certainty how long this process will take," the spokeswoman said.

EDF Energy's 15 nuclear reactors provide about 20 percent of Britain's electricity. Almost half of that capacity is due to go offline by 2025.

EDF said it still expects Hunterston to close in 2023.

Britain's Centrica also owns a 20 percent stake in the nuclear fleet but hopes sell this by the end of 2020.

(Reporting by Susanna Twidale; Editing by David Goodman)