Loviisa Y1 is a 992 MW nuclear power station in Uusimaa, Finland. It is operated by Fortum Power & Heat Power. Based on reported annual generation of 8,171 GWh, it can supply roughly 2.3 million homes. It ranks #4 of 203 Finland power plants by installed capacity. Commissioned in 1977, it is around 49 years old — long-established. As a non-combustion source, it has no direct CO₂ emissions from generation. In context, nuclear supplies about 39.9% of Finland's electricity; the national grid averages 57 gCO₂/kWh (96.3% low-carbon) (2025).
Plant data: WRI Global Power Plant Database (CC BY 4.0), id WRI1002445.
Known, modelled and calculated values are kept separate. Missing fields are shown as unavailable.
The capacity and/or fuel fields on this page include a source-backed provenance label from GEM, an official registry, Wikidata, OSM, or a cross-source match.
capacity: GEM tracker 2026 (location L100000500194); fuel: WRI source-record fuel
Technically it is described as pressurized water reactor. Nuclear plants split uranium to raise steam with no direct CO₂; they run as steady baseload with very high capacity factors and the longest operating lifetimes of any thermal plant.
Capacity comparison computed from the WRI Global Power Plant Database; fuel-type context is general engineering background.
Annual generation (GWh), WRI Global Power Plant Database (CC BY 4.0).
Operated by Fortum Power & Heat Power.
This nuclear plant uses heat from nuclear fission to raise steam for a turbine-generator. It sits in a warm-summer humid continental climate (Köppen Dfb) — Northern Hemisphere, latitude 60.4°N — which shapes how much energy it can produce and how its output varies through the year.
Monthly mean temperature
Heating degree-days here run 98% above the median power plant in this dataset — a proxy for how much extra energy heated equipment must replace through its surfaces in winter.
Climate heat-demand index: 93/100 — this site sits in the top third of the power plants we cover by heating degree-days.
Climate normals: WorldClim 2.1 (1970–2000 monthly normals, 10 arc-min, CC BY 4.0); zone: Köppen-Geiger world climate classification (Kottek et al. 2006, 0.5° grid). Degree-days & heat-demand index computed by PowerAtlas — a modelled heat-demand proxy, not a measured site figure.
For a plant’s outdoor hardware — heat-recovery steam generators (HRSG), expansion joints, valves, flanges and their insulation — the local climate sets how fast unprotected steel and coatings degrade. This site sits in a moderately corrosive environment (estimated ISO 9223 class C3 — Medium), with humidity / wetness the leading environmental stress.
Higher environmental severity is exactly where protective removable insulation pays back most: a sheltered micro-climate slows corrosion, UV and thermal-cycling damage and extends outdoor hardware service life. This is an indicative site-climate context — not a condition assessment of any specific plant or operator.
Indicative estimate via the ISO 9223:2012 informative method (atmospheric corrosivity from temperature, time-of-wetness and airborne salinity), using WorldClim climate normals, the Köppen-Geiger class and coast distance. Indicative, not a measured corrosion rate.
The #3 largest nuclear power plant of 3 in Finland by capacity.
Finland has 3 nuclear power plants in this dataset, together about 3,952 MW of capacity.
Coordinates 60.3708, 26.3468 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.
Loviisa Y1 is a 992 MW source-record nuclear power plant in Uusimaa, Finland, commissioned in 1977.
Loviisa Y1 generates about 8,171 GWh of electricity per year.
Its output is enough to supply roughly 2,334,542 homes.
Loviisa Y1 is operated by Fortum Power & Heat Power.
