Two of Finland nuclear power plants are set for annual maintenance this spring, according to operator TVO.

The Olkiluoto 2 (OL2) plant unit is scheduled to be shut down for about ten days starting on Monday April 6, the firm said in a press release.

"Various annual preventive maintenance tasks, inspections, repairs and tests will be carried out at the plant unit in addition to refuelling. The plant unit's power reduction for the annual outage will begin already on Sunday, 5 April, when the unit's output will be reduced to about half to enable the tests carried out at that time," the release read.

After routine maintenance on OL2 is carried out, work on OL1 is scheduled to begin on Sunday, 19 April.

OL1 will be offline for approximately 55 days, according to the company.

"The long duration of the outage is due to the implementation of several extensive work tasks and plant modifications," it explained, noting that OL1's outage is scheduled to end on 13 June.

Regular maintenance on the company's newest and biggest reactor, OL3, is scheduled to take place in September and October.

According to TVO, outages are carefully planned and the work involved "is performed in several shifts around-the-clock".

"In addition to TVO's in-house personnel, approximately 1,400 contractor employees [will] participate in the annual outages this spring," the company said.