The operator of Germany's Isar 2 nuclear power plant has informed the environment ministry of a leak at the site, which has not compromised security but could complicate the government's winter energy plan, the ministry says.
A week-long repair period is needed, during which operations would come to a standstill, if the power plant is to operate beyond December 31, the ministry added.
Isar 2, situated 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.
However, the war in Ukraine and the subsequent plunge in energy imports from Russia prompted a policy change, with the government now planning to keep two of the three remaining nuclear power stations on standby into next year.
The environment ministry said both it and the economy ministry were "examining the new situation and its implications for the design and implementation of the standby reserve".
PreussenElektra, a subsidiary of E.ON and operator of Isar 2 said the reactor could continue to operate until the planned shutdown date, according to the environment ministry.
But the week-long shutdown would be necessary in October if the plant were to run beyond the end of this year.