PARIS- The 900 megawatt (MW) Bugey 3 nuclear reactor in eastern France is expected to be back in operation on Friday after being taken offline on Thursday evening following detection of an overheating connection to a high-voltage line in a non-nuclear part of the facility, power group EDF said.

Statutory outages can sometimes last several days longer than the initial expected restart date.

The service team was mobilised for repairs to bring the reactor back online as soon as possible, EDF said, adding that the disruption did not affect plant safety.

The 1,500 MW Chooz 1 reactor outage date was also extended to Dec. 31 from the expected restart date of Feb. 11. Chooz 1 was taken offline in December after corrosion was detected in some pipes at the plant.

A Chooz 1 outage extension was already factored into grid operator RTE's revised winter outlook.

Separately on Friday, EDF cut its estimate for its French nuclear output in 2023 to 300-330 terawatt hours (TWh) from 340–370 TWh, having cut its 2022 nuclear output eastimate at the start of the week

The company has also said that all French nuclear reactors will be subject to corrosion checks but will not necessarily need to be halted. 

Current French nuclear availability is at 75.8% of installed capacity. Nuclear accounts for about 75% of power generation in France. 

(Reporting by Forrest Crellin Editing by David Goodman) ((Forrest.Crellin@thomsonreuters.com;))