Sweden's Oskarshamn 3 reactor to stop for checks for nine days (updated)

Fortum Oyj

09/12/2025 09:14

Updates throughout with operator's statement

OSLO, Dec 9 (Reuters) -
Sweden's Oskarshamn 3 nuclear reactor will be offline from December 11-20 to check anomalies in its process water flow, operator OKG, owned by Uniper UN0k.DE and Fortum FORTUM.HE, said on Tuesday.

The 40-year-old reactor, which has an installed power capacity of 1.4 gigawatts, will go offline on Thursday night local time, OKG said in a market message posted via power exchange Nord Pool.

In a separate statement, OKG said it had detected a small deviation in the values ​​that measure the flow of process water from the reactor enclosure to the purification facility, and it would stop the reactor to rectify any faults.

        "The deviations are small and well below the applicable limits and have no impact on reactor safety either, but due to this year's long shutdown, we are starting a fault finding before winter is here," OKG said.

The reactor - Sweden's largest -
restarted
 on November 2 after an outage lasting seven months.

German utility Uniper owns 54.5% of OKG, with Finnish company Fortum owning the remaining stake.

 (Reporting by Nora Buli, editing by Terje Solsvik)

 ((Nora.Buli@thomsonreuters.com; (+47) 21 04 05 56; Reuters Messaging: nora.buli.thomsonreuters.com@reuters.net))