Test operation of Finnish EPR resumes

09 August 2022

The test production phase has resumed at the Olkiluoto 3 EPR in Finland following the completion of maintenance and repair activities in the plant's turbine island. Operator Teollisuuden Voima Oyj (TVO) said the tests will now continue at a power level of 60%, increasing to 80% in mid-August and reaching full power in September.

The Olkiluoto 3 EPR (Image: TVO)

In June, TVO said the issue of foreign material in the steam reheater of Olkiluoto 3's turbine had delayed the start of regular electricity generation by three months until December. Material that had detached from the steam guide plates was found in the turbine's steam reheater in May this year, which required inspection and repair work. This repair work was due to last until the end of July.

With that work now complete, test production at the reactor has now resumed. TVO noted that at 60% capacity - equivalent to a power output of about 850 MWe - Olkiluoto 3 provides about 10% of the current electricity consumption in Finland.

The utility said the purpose of the test production phase is to put the plant unit through different tests in varying conditions and at varying power levels. The operational capability of the national grid in case of sudden power cuts is also tested at the same time. It said any needs for repairs or maintenance works identified in the tests are addressed during the test operation phase. In addition, based on previous experience from the test production phase, the schedule includes time for full-scale plant tests and its analysis.

"The tests carried out at the plant unit during the test production phase last from a few hours to several days," TVO said. "During the tests, the plant unit is operated at significantly lower power levels or completely disconnected from the national grid.

"According to the test schedule given by the plant supplier, test operation will proceed to 80% power level tests after mid-August. With a power output of approximately 1300 MW at that power level the Olkiluoto 3 plant unit will be bigger than any other Finnish power plant unit. The first full-power tests where the power unit will produce electricity at an output of about 1600 MW are scheduled in September."

TVO said the test production phase of the plant unit is still expected to be completed in December, after which Olkiluoto 3 can proceed to regular, full-power electricity production.

The Areva-Siemens consortium constructed the OL3 plant under a fixed-price turnkey contract. They have joint liability for the contractual obligations until the end of the guarantee period of the unit. Construction of Olkiluoto 3 began in 2005, with completion of the reactor originally scheduled for 2009, but the project has had various delays and setbacks.

OL3 attained first criticality on 21 December last year and was connected to the grid on 12 March. At that time, TVO said a test production phase, lasting about four months, would follow during which OL3's power output will be gradually increased to 100%.

Once regular electricity production has started, OL3 will produce about 14% of Finland's total electricity consumption.

Researched and written by World Nuclear News