Regular electricity generation at unit 3 of Finland’s Olkiluoto NPP (OL3), an  Areva-supplied 1600MWe European Pressurised Reactor (EPR), has again been pushed back by a further four months and is now expected to begin in January 2020, Teollisuuden Voima Oyj (TVO) has announced.

In October, the Areva-Siemens consortium, which is building the unit, said it wanted to update the schedule because commissioning tests were taking longer than planned.  Areva-Siemens said fuel will now be loaded into the reactor core in June 2019, with grid connection scheduled for the following October, and the start of regular electricity generation for January 2020.

Under the previous schedule announced in June, fuel loading was expected in January 2019, grid connection in May with the start of regular electricity production in September.

Hot functional testing began last December and was completed in late May, 50 days later than planned. The delay was due to vibrations in pressuriser surge line. As a result of the test results, TVO said a comprehensive modification package would be implemented at OL3 to update the plant's electrical and instrumentation and control systems. TVO now says the commissioning tests will take longer than expected and are still ongoing.

"The final automation modification package will be implemented and the pressuriser surge line vibrations will be repaired by modifying the pipe
support, and the commissioning test will be continued," the company said. "After modifications, the necessary commissioning tests will be repeated, and commissioning will continue." According to the commissioning programme, OL3 will generate 2-4 TWh of electricity at different power levels during the tests, which will begin at grid connection and end when regular electricity production starts.

"We are disappointed in the schedule delays, but it is key that the entire commissioning is carried out carefully, without compromises,” said OL3 project director Jouni Silvennoinen in a statement.

Construction of the first-of-a-kind EPR at OL3 began in 2005 under a turnkey contract signed in late 2003. The project was initially planned for completion in 2009, but  has suffered various delays and court battles. After a long-running court dispute, which was settled in March, Areva agreed to pay TVO €450m for cost overruns and the delays. OL3 will be Finland’s fifth and largest nuclear reactor and provide about 10% of its power needs.

Photo: Olkiluoto 3 project director Jouni Silvennoinen (credit: TVO)