The annual outages for 2017 at Finland’s Olkiluoto nuclear power plant were completed on 14 July when unit 2 (OL2) resumed electricity production, plant owner/operator Teollisuuden Voima Oyj (TVO) said last week. The annual outages for units 1 and 2 started on 23 April. The outage at OL2 this year was the longest in the history of the reactor, at 64 days. However, OL1 was closed only for a short fuel replacement outage that took ten days.
Major work undertaken at OL2 included replacement of the reactor recirculation pumps and their frequency converters, renewal of the neutron flux calibration system as well as modernisation of the heating system that contributes to residual heat removal. The turbine condenser was also replaced. Some repair work was carried out in the reactor pressure vessel, as well. The pipe nozzles of the pressure vessel were repaired using a method never before used in Finland.
TVO started the planned repair of the pipe nozzles during the outages by repairing the cracks found on the nozzles of OL2. The repair was implemented by machining the weld on the inside of the nozzle and welding a new deposit coating using a weld metal less susceptible to stress corrosion.
All in all, the duration of the annual outages took 24 days longer than expected. The complex welding works on the pipe nozzles were the cause for the delay. Both units are 880MWe boiling water reactors, which began commercial operation in 1979 and 1982. TVO said OL1 and OL2 play an important part in the base load production and have been producing electricity for almost 40 years. Electricity produced at the units accounts for about 17% of the Finnish electricity consumption and about 22% of the electricity produced in Finland.
Earlier, on 12 July, TVO announced that it is restructuring its organisation as of 1 August in preparation for the start-up of Olkiluoto 3, an EPR under construction by Areva and Siemens, which has is now nine years behind schedule and significantly over-budget. The reorganisation “is to strengthen the company's capabilities in executing its strategy in the changing operating environment as the operational phase of the OL3 EPR plant approaches”, TVO said.
From the current members of the TVO Management Group, Marjo Mustonen has been appointed Senior Vice President, Electricity Production. She was previously responsible for the construction of the OL3 unit. Mikko Kosonen has been appointed Senior Vice President, Safety, after nine years of experience in the position of Production Director. In addition to his responsibility for legal affairs of the Group, Risto Siilos has been put in charge of the Legal Affairs and Procurement function and will act as Secretary to the Board of Directors and Deputy to the President and CEO. In the new organisation, Anja Ussa, Senior Vice President, Finance, will also be in charge of IT, Business Development and Support Services.
The Management Group will have two new members, Pekka Frantti (responsible for ensuring the financial interests and conditions of OL3) and Jaana Isotalo, who has been appointed Senior Vice President, HR. Preparations for the upcoming operational phase of the new plant unit also include the recruitment of dozens of new experts and employees, TVO said.
Photo: Olkiluoto site (Credit: TVO)