Finnish power company Teollisuuden Voima Oyj (TVO), owner-operator of the Olkiluoto NPP, has said that the investigation into damage to the internal parts of the Olkiluoto 3 EPR feedwater pumps are continuing. Damage had been detected in the inner parts of the feedwater pumps of the Olkiluoto 3 (OL3) turbine plant, “the causes of which are currently being investigated in several different laboratories”, TVO noted. “The schedule for the continuation of the trial operation programme will be updated once the cause of the damage and the repair method have been determined.”

Cracks a few centimetres long were found in all four feedwater pumps of OL3. “There is still no certainty about the origin mechanism of the cracks found in the impellers of the pumps. Cracks were discovered during repair and maintenance work,” TVO said. The feedwater pumps of the OL3 turbine plant are of a design generally used in power plants, but larger pumps were designed for the operation of OL3. “The feedwater pumps are the largest pumps in Olkiluoto 3 and they are used to pump water from the feedwater tank to the evaporators. The detected cracks have no impact on nuclear safety,” TVO added. “The possible effects of the results of the investigations on the schedule will be communicated as soon as the investigations are completed.”

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 OL3 began in 2005, with completion of the reactor originally scheduled for 2009, but the project has faced various delays and setbacks. OL3 achieved first criticality in December 2021 and was connected to the grid in March. The 1600 MWe pressurised water reactor is currently in an ongoing test production phase. It was operated at full capacity for the first time in late-September and is currently scheduled to start regular electricity production in December.

Among the many questions and answers on TVO’s “OL3 Frequently Asked Questions” page are the following:

  • Can you honestly say that everyone working at OL3 in Olkiluoto is up to the task? — Yes. TVO has at its disposal decades of experience in the operation, maintenance and handling of malfunctions of the Olkiluoto 1 and Olkiluoto 2 nuclear power plant units. Therefore, it is clear that OL3 is also staffed by highly trained and experienced nuclear industry professionals who operate in accordance with the principles of a high safety culture. For us professionals in the core industry, maintaining our own skills and training is everyday life. Continuous improvement is also essential in our operations. Versatile tools and international networks from other nuclear facilities are used to prevent human errors.
  • Could it be that the owners of Teollisuuden Voima or the employees of the plant supplier are deliberately delaying the completion of OL3 in order to keep the well-paid jobs as long as possible or to keep the price of electricity high? — No. The owners of Teollisuuden Voima, the entire staff and the employees of the plant supplier absolutely want the new plant unit to be ready and ready for regular electricity production as quickly as possible without jeopardising the safety of the plant unit. For this reason, the test operation period is carried out carefully in such a way that the use of the plant unit has been tested in a versatile way at different power levels. This is the only way to ensure stable and predictable electricity production far into the future, which is absolutely important from the point of view of the self-sufficiency of electricity production in Finland.

Image: One of the feedwater pumps at Olkiluoto 3 (courtesy of TVO)