Finland's Loviisa Nuclear Power Plant to Remain Offline Longer as Fortum Launches Major Modernization Program

Helsinki – Finland's Loviisa nuclear power plant will shut down in early August for its annual maintenance outage, with this year's shutdown lasting significantly longer than usual and scheduled to conclude on October 18. The extended outage reflects a major overhaul of Unit 2 – performed only once every eight years – as well as the launch of extensive modernization projects.

Like coal- and gas-fired power plants, nuclear power plants are thermal power stations and require regular shutdowns for maintenance. During the outage, turbines, pumps, and other conventional plant components are inspected and upgraded alongside the reactor and fuel assemblies. The plant's two units, which entered operation in 1977 and 1980, are slated to remain in operation until the end of 2050.

Major Overhaul and Modernization Projects Extend Outage

The maintenance campaign begins on August 2, 2026, with Unit 2, followed by the annual outage of Unit 1. Both reactor units will be serviced consecutively during this year's maintenance campaign, with all work scheduled for completion on October 18.

Unit 2 will undergo a comprehensive overhaul carried out only once every eight years. Planned work includes inspection and pressure testing of the reactor pressure vessel, replacement of one-quarter of the fuel assemblies, and extensive maintenance and refurbishment work. Unit 1 will undergo its regular annual maintenance outage.

As with other thermal power plants, the entire conventional plant will also be inspected, including turbines, pumps, piping, valves, and instrumentation and control systems. These activities will be complemented by inspections of nuclear safety systems and replacement of fuel assemblies. Around 1,000 contractor personnel will support the plant's approximately 570 permanent employees during the outage.

Fortum currently estimates that investments of up to EUR 1 billion will be required to keep the plant operating until the end of 2050. By then, Unit 1 will have been in operation for 73 years and Unit 2 for 70 years.

Western Nuclear Fuel Replaces Russian Supplies

Alongside the technical modernization program, Fortum is continuing its transition to Western nuclear fuel. Fuel assemblies supplied by Westinghouse have been introduced gradually since 2024. Following completion of this year's outage, the majority of the plant's nuclear fuel will originate from Western supply chains.

Together with Framatome and other European partners, Fortum is also developing a fully European fuel design for WWER-440 reactors, with the aim of permanently eliminating dependence on Russian fuel supplies.

About the Loviisa Nuclear Power Plant

The Loviisa nuclear power plant is located approximately 90 kilometers east of Helsinki and consists of two Soviet-designed WWER-440/V-213 pressurized water reactors. Unit 1 entered operation in 1977, followed by Unit 2 in 1980. Following extensive modernization, both units now have a net electrical output of 507 MW, giving the plant a combined net capacity of 1,014 MW.

The Finnish government has approved in principle the continued operation of the plant until the end of 2050, a decision embedded in the ongoing oversight process of Finland's nuclear regulator, STUK. Fortum, the majority state-owned Finnish energy company, is required to demonstrate safe operation throughout the plant's lifetime through periodic safety reviews and to implement any upgrades required.

Between 2020 and 2025, the Loviisa plant generated an average of approximately 7.95 terawatt-hours of electricity annually, corresponding to nearly 7,850 full-load hours per year. Over that period, Loviisa supplied roughly 10 percent of Finland's total electricity generation on average.

Source: IWR Online, 30 Jul 2026