Operations in Loviisa Nuclear Power Plant

Loviisa nuclear power plant is a condensate power plant that produces electricity, and its power plant units are pressurised water plants. Electricity generation at the plant is based on the utilisation of thermal energy generated by a controlled fission chain reaction.

Workers outside of Loviisa Nuclear Power Plant

Loviisa NPP in 2023


Loviisa NPP production (TWh)


Share of Finland's electricity production


The power plant continuously employs

Finland's first nuclear power plant

 Loviisa 1Loviisa 2
Construction began1.5.19711.8.1972
Heat capacity1,500 MW1,500 MW
Power capacity (net)507 MW507 MW
Load factor (2023)89.79%92.32%
Power generation (2023)3,99 TWh4.10 TWh

Primary circuit

The Loviisa power plant units' reactor coolant pumps circulate the 300-degree water into the steam generators and back to the reactor. The Loviisa power plant units contain a total of six of these circuits working in parallel. Together they form the primary circuit of the reactor.

Secondary circuit

In the steam generators, the water of the primary circuit heats the water of the separate secondary circuit. The water starts to boil because the pressure in the secondary circuit is much lower than in the primary circuit. The generated steam is led to the turbines. The turbine rotates the generator, which converts the kinetic energy into electricity.

Cooling water system

After the turbine, the low-pressure steam is led to the condensers. There the steam is condensed with cold seawater back into the water, which is then pumped through the preheaters into the steam generators. When both power plant units are operational, it takes on average about 40 cubic metres of seawater per second to cool the steam. The water used in the cooling is pumped back into the sea. It is 10 degrees warmer but its consistency is unchanged. The rest is transmitted to the cooling water in the condensers and from there to the sea, just like in other condensing power plants generating electricity.


Nuclear power

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