Loviisa power plant environmental report: Our environment 2022

The annual collective radiation dose of the Loviisa power plant’s own personnel and external contractors in 2022 was the lowest in the plant’s operating history. This shows that long-term work in radiation safety produces good results.

Emissions of radioactive effluents into the environment in 2022 were, as in previous years, significantly lower than the limits set for nuclear power plant emissions.

Based on emissions and meteorological data, the estimated radiation dose to the surrounding population was about 0.2% of the set dose limit. The radiation dose to the surrounding population from radioactive substances originating from the Loviisa power plant accounted for only a minor increase compared to the radioactive dose from other sources (like, e.g., radon and medicine).

The radiation monitoring programme carried out in the power plant surroundings occasionally detected radionuclides originating from the plant, but the concentrations detected were very small.

Waste management at the Loviisa power plant is comprised of two separate areas: waste management for the non-controlled area and waste management for the controlled area. All waste generated in the controlled area is treated as radioactive. Waste generated outside the controlled area can be treated as waste from a conventional industrial plant.

The goal of conventional waste management is to prevent the production of waste and to reduce the amount of landfill waste through effective sorting. In 2022 about 639 tonnes of waste was transported from the power plant area. Of this, 21% was landfilled, 58% was reused as materials or energy, and 12% was treated as hazardous waste.

Waste generated in the controlled area is divided into three categories: Low-level waste (maintenance waste), intermediate-level waste (liquid waste), and high-level waste (spent fuel). Maintenance waste is either cleared as non-active and treated as conventional waste or disposed of in the final repository located at a depth of 110 metres in the power plant area. Also the solidified liquid waste was disposed of in the final repository.

Thanks to efficient sorting and packaging, in 2022 a small proportion of maintenance waste went to final disposal. Liquid waste is purified and released into the sea or stored and solidified in concrete and then disposed of in the final repository. Spent fuel is stored to await final disposal in Eurajoki.

The power plant’s most significant environmental impact is the thermal load on the sea caused by the cooling water, which heats up by about 10 degrees as it passes through the plant. In practice, two-thirds of the thermal energy produced by the reactor ends up in the sea with the cooling water. According to temperature measurements, the discharged water raises the temperature of the sea water during the growing season by about 1-2.5 degrees within a 1-2 kilometre range from the discharge point.

The cooling water discharge area remains unfrozen throughout the winter. The size of the open water and thin ice area depends on winter temperatures. In 2022, the power plant used a total of about 1,323 million m3 of sea water for cooling, and the thermal load on the sea totalled 55,156 terajoules.

In accordance with the environmental permit, the amount of cooling water released into the sea should not exceed 1,800 million m3 per year or 56 m3/s. The cooling water’s thermal load on the sea may not exceed 60,000 terajoules annually. The limits set by the permit were not exceeded in 2022.

The process and domestic water required by the power plant is sourced from Lake Lappominjärvi, which is located about 5 kilometres north of the power plant.

The water is purified before use at the water plant, and the water used as process water is additionally treated at the demineralisation plant. The total volume of water withdrawn from Lake Lappominjärvi in 2022 was about 131,736 m3.

According to the service water withdrawal permit, the power plant can withdraw up to 180 m3/h of water from the lake for a short period of time and a maximum of 150 m3/h per quarter.

The domestic wastewater generated is treated at the power plant area’s biological-chemical wastewater treatment plant, to which about 18,028 m3 of wastewater was piped in 2022.

In accordance with the environmental permit, domestic wastewater must be treated so that the biological oxygen demand (BOD7ATU) of wastewater discharged into the sea does not exceed 15 mg/l and the total phosphorus concentration does not exceed 0.7 mg/l, calculated as annual averages. The efficiency of the treatment process must be at least 90% for both variables.

According to the monitoring results, the treatment plant reached results compliant with the conditions of the permit: the biological oxygen demand of treated wastewater in 2022 was 1.9 mg/l on average and total phosphorus concentration 0.17 mg/l. The load caused by domestic wastewater in 2022 was 3.0 kg of phosphorus, 942 kg of nitrogen and 263 kg of solids.

The environmental permit of the power plant does not set any limits for the process wastewater load. However, the nutrient load caused by the process wastewater is monitored through samples taken in accordance with the monitoring programme.

The load caused by process wastewater in 2022 was 0.5 kg of phosphorus, 317 kg of nitrogen and 31 kg of solids. The power plant’s share of the total load in the Hästholmen sea area in 2022 was about 1% phosphorus and about 5% nitrogen.