Olkiluoto produced last year about 31 percent of the electricity consumed in Finland

This is the highest production volume ever in the history of Olkiluoto. It was naturally due to the fact that instead of two plant units, there are now three units operating in regular electricity production.

After the start of regular production at Olkiluoto 3, the unit was only out of production for under four days.

The most recent of the plant units, Olkiluoto 3, already produced 1.9 TWh of electricity in 2022 when it was still undergoing the test production phase. Actual regular electricity production was started at OL3 in the early hours of the morning on 16 April 2023.

Despite the year 2023 not being anywhere close to a full production year for 2023, the newest plant unit still produced by far the most electricity of all three units in Olkiluoto. OL3 produced 10.37 TWh of electricity to the national grid last year. That is 42% of the whole production volume in Olkiluoto.

- The year 2023 was a historically great year for Olkiluoto. All three plant units of Olkiluoto are now in operation with a combined power output of about 3380 MW, says Marjo Mustonen, Senior Vice President, Electricity Production.

Since the start of regular electricity production at Olkiluoto 3, the unit has been a stable and secure electricity producer with the exception of two brief unplanned disruptions in production in November 2023. Both of the unplanned interruptions of production were caused by turbine trips; one of which resulted from a fault in the protection system's measuring instrument, and the other from a turbine trip lock occurring during a nearby fault test.

After the start of regular electricity production, the production of OL3 has been interrupted for a total of 84 hours due to technical investigations or faults.On the other hand, the plant has been in production for 6155 hours. In other words, production disruptions only account for 1.4% of the total operating time.

Two older Olkiluoto units in good shape

Production year 2023 was a solid one also for the Olkiluoto 1 and Olkiluoto 2 plant units. OL1 produced 7.42 TWh of electricity and the production volume of OL2 was 6.87 TWh. Olkiluoto 1 produced slightly more electricity than in previous years, but at Olkiluoto 2, the production was reduced by a leak detected in August 2023 in the cooling system of the water-cooled generator and the subsequent replacement of the rotor of the generator. OL2 was out of operation for 17 days.

The two older plant units in Olkiluoto that have already been in operation for well over forty years have been modernised every year with tens of millions of euros. In 2023, about 60 million euros were invested in maintenance and modification activities at the plant units.

In fact, an ongoing investigation is looking into extending the operating licences for the Olkiluoto 1 and Olkiluoto 2 plant units and a potential power increase. The Environmental Impact Assessment process launched in the autumn of 2023 is expected to go on for months.

Final disposal of spent fuel getting ever closer to starting

The operations of Posiva Oy, another nuclear facility on the island of Olkiluoto, also proceeded according to plans in 2023. At the encapsulation plant, the year was particularly characterised by equipment and system installations. In addition, the personnel elevator which provides a quicker access to ONKALO for the personnel was put into operation in the autumn of 2023. The final disposal of spent nuclear fuel in Olkiluoto is scheduled to start in mid-2020s.

For further information, please contact:

Johanna Aho, Head of Communications, tel. +358 40 729 0822