FRANKFURT, Aug 22 (Reuters) - Switzerland's biggest nuclear power station at Leibstadt will extend its outage for maintenance by eight weeks until Oct. 29, its operator said on Monday, after discovering discolouration in eight cladding tubes used to encase fuel rods.
Plant operator KKL AG said in a statement that the tubes needed to be further assessed and swapped, as they pointed to oxidation problems.
However, it said "the integrity of the fuel elements (themselves) is not affected."
The 1,245 megawatt (MW) reactor was originally meant to be offline between Aug. 2 and Aug. 27.
The problems now established were advanced enough to make the fuel elements unusable for the plant's next operating cycle, resulting in the eight week delay, KKL said.
Nuclear plant downtimes have to be made public under laws governing the sector.
They are also noted by wholesale power traders because they take big slices of supply out of the market, which operators have to compensate for from other sources in order to meet delivery obligations.
Switzerland's power market interacts with those of neighbouring France and Germany, Europe's biggest consumers of electricity in a region where cross-border trading is common and prices converge. (Reporting by Vera Eckert, editing by Susan Fenton)