FRANKFURT German nuclear operator E.ON on Thursday said its closed Grohnde reactor was expected to reopen on June 20, in line with a six-week closure extension earlier this month resulting from a generator fault.
Energy traders' talk that additional findings in an ongoing probe at the plant might lengthen its outage had boosted European carbon emission permits prices.
Longer-than-expected absences of carbon-free nuclear capacity in the power market create demand for more mandatory pollution rights that electricity generators must hold under EU law to cover their production.
Nuclear outages also take big slabs of power supply out of the wholesale market and are costly for operators.
"Based on the current status, we assume that all necessary jobs can be completed in the so far anticipated outage period," said plant director Walter Boewing in a statement issued by E.ON's nuclear power subsidiary, E.ON Kernkraft.
"Consequently, we plan to end the plant's maintenance on June 20," he added.
E.ON said it had examined 105 of the plant's 132 flow restrictors, which are tools for cooling the nuclear system, after a faulty spring had been detected in one of them during the standstill. While engineers had found faults at six springs, the functionality of the equipment was fully intact, E.ON said.
The faulty parts discovered to date had been swapped out.
A report on the findings and the ensuing procedures had been sent to the local nuclear supervisory authority, the Lower Saxony environment ministry, E.ON said.
It also said that a replacement generator had been delivered to the plant.
The Hanover environment ministry said earlier on Thursday it expected E.ON's report on measures at the plant at the weekend and would publish its further assessment next week.
Grohnde last year produced 11 billion kilowatt hours of electricity, equivalent to four years of supply to Lower Saxony capital Hanover with a population of half a million.
(Reporting by Vera Eckert, editing by David Evans)