Finland's new nuclear reactor start-up plan hit by valve leak

HELSINKI, May 25 (Reuters) - The long-delayed Finnish Olkiluoto 3 nuclear reactor was hit by another set-back as Finland’s safety watchdog said on Monday that valve problems had been found in its primary circuit, which is involved in the cooling process.

The reactor in western Finland, built by a consortium of France’s Areva and Germany’s Siemens, had been due to start producing electricity in November 2020.

“A leak was observed in the mechanical control valve of one of the pressurizer safety valves,” nuclear watchdog STUK said in a statement, adding that a full investigation was required before it would issue a nuclear fuel loading permit.

“This is very serious,” STUK’s head of inspection Iiro Paajanen told Reuters of the leak, which he said was in part of the reactor’s primary circuit and involved in its cooling.

Reactor operator Teollisuuden Voima (TVO) applied for fuel loading on April 8, saying it expected a permit to be issued in a couple of months.

However, it warned that the coronavirus pandemic would delay fuel loading from a planned June schedule, possibly also pushing back the November start-up.

“A few technical issues have appeared during the test runs and they will be solved before the fuel is loaded,” TVO said in a statement, adding that the supplier is updating the schedule.

Standard & Poor’s downgraded TVO’s long term credit rating to BB after TVO’s announcement in April.

Although Finland’s government issued an operating permit for the 1.6 gigawatt reactor in March 2019, OL3 needs final approval from STUK to load fuel and start production.

“At present, the plant unit still has several outstanding issues before (a) loading permit can be issued,” STUK wrote in its January-April safety report.

Areva was not immediately available for comment. ($1 = 0.8868 euros) (Reporting by Anne Kauranen and Tarmo Virki; Editing by Alexander Smith)