The annual maintenance outage at Finland’s Olkiluoto 2 was brought forward four calendar days because of measures taken to remove damaged fuel from the reactor, plant owner Teollisuuden Voima Oyj (TVO) said on 29 April.
Some radioactive substances had been released from the fuel into the reactor water but did not pose a threat to the environment, TVO added.
Annual maintenance started on 1 May instead of 5 May and is scheduled to end on 26 May. In addition to refuelling, the most important work includes primary circuit pressure tests, rebuilding of the reactor water purification system, replacement of the low voltage power supply modules for the containment and replacement of the 400 kV switchgear. Damaged fuel elements will be removed from the reactor and replaced with new ones.
The annual refuelling outage for Olkiluoto 1 is planned for 2-5 June and ends on 11 June, according to the schedule. The main work is fuel change.
Olkiluoto 1&2, both 890 MWe boiling water reactors, began commercial operation in 1979 and 1982 produce 22% of Finland’s electricity. In October 2017 TVO also shut down Olkiluoto 1 to check for fuel damage.
Photo: Olkiluoto nuclear site