Annual outages completed at Olkiluoto

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The annual outages of Olkiluoto were completed on Friday, 18 June at 05:52 when the Olkiluoto 2 plant unit (OL2) was connected back to the national grid. The annual outages lasted for a total of eight weeks, and they proceeded well with all the necessary COVID-19 arrangements in place.

The annual outage for OL1 consisted of refuelling and several other tasks, some of which were postponed from last year’s annual outages due to the coronavirus epidemic. The work included main transformer replacement and a pressure test of the reactor primary circuit. The refuelling outage started on 25 April and ended on 11 May. 

The annual outage for OL2 started on 16 May and ended on 18 June. In addition to refuelling, major works during the service outage included pump and piping replacements in the shut-down cooling system, replacement of containment electrical penetration modules, feed water system recirculation line modification, containment leak-tightness test and inspection and vacuum cleaning of the reactor pressure vessel bottom.

In addition to TVO’s own personnel approximately 800 external resources participated in the refuelling outage and 1,000 external people worked in the service outage. Most of these resources came from the Satakunta region and the neighbouring areas. Approximately one hundred specialists arrived from abroad for the annual outages.

The Olkiluoto nuclear power plant is kept in good condition by alternating between refuelling outages and service outages at both plant units.


Teollisuuden Voima Oyj has produced electricity for its shareholders, Finnish industrial and energy companies, safely and reliably for 40 years. Nuclear electricity generated at TVO's Olkiluoto plant covers approximately one sixth, increasing to nearly one third once Olkiluoto 3 EPR is completed, of the electricity consumption in Finland. Climate-friendly nuclear electricity not only benefits society but also reduces the environmental impact of energy production. Moreover, the world's first final disposal facility for spent nuclear fuel is under construction in Olkiluoto.