E.ON has informed the German government of a leak at the Isar 2 nuclear power plant which has not compromised security but could complicate the government's winter energy plan, the environment ministry said on Monday.
Isar 2, in the southern state of Bavaria, had been scheduled to go offline at the end of the year under Germany's plan to phase out nuclear power.
But the war in Ukraine and the subsequent plunge in energy imports from Russia prompted a policy change, with Berlin now planning to keep two of Germany's three remaining reactors, including Isar 2, on standby into next year.
The ministry said that a week-long repair period is needed in October at the Isar 2 plant, which is run by E.ON subsidiary PreussenElektra, during which operations would stop completely.
A spokesperson for E.ON said it was confident that a framework allowing Isar 2 to add to Germany's power supply security beyond Dec. 31 could be agreed with the government.
"Due to the necessary lead times, however, it is now necessary for the ongoing political discussions to quickly lead to a clear result and for all those involved to create planning security as quickly as possible," the spokesperson added.
Germany's environment ministry said that together with the economy ministry it was "examining the new situation and its implications for the design and implementation of the standby reserve" of the Isar 2 development.
The EEX transparency site, where operators have to place mandatory messages on plant outages to the wholesale power market, did not show an entry on Isar 2 for October.
E.ON's spokesperson said it would inform the market of any development as and when required by German law.