793 Technical project description

order to ensure that their radioactivity remains below the set limits. (STUK 2013a) The environmental impact of the emissions will be very low in comparison with radioactive substances occurring naturally in the environment.

3.16.1 Radioactive emissions into the

atmosphere

According to the Government Decree (717/2013), the radi- ation dose to individual inhabitants of the surrounding area caused by normal operation of a nuclear power plant may not exceed 0.1 millisieverts per year. This limit value functions as the basis for the determination of the limits for emissions of radioactive substances during normal opera- tion. Emission limits will be established for iodine and inert gas releases. The set emission limits are power plant-spe- cific. In addition to iodine and noble gas emissions, trit- ium, carbon-14, and aerosols are also released from nuclear power plants into the atmosphere. Even at the theoretical maximum level, the annual emissions of these substances remain so low that setting separate emission limits for them is unnecessary. However, these emissions are also measured. All substances with a significant impact on the total dose rate are taken into account in the determination of the annual dose rate to the inhabitants of the surrounding area. In practice, this applies to the iodine and noble gas releases, as well as the tritium, carbon-14, and aerosol releases, men- tioned above.

The Fennovoima nuclear power plant will be designed so that the emissions of radioactive substances remain below all set emission limits. Furthermore, Fennovoima will determine its own emission limit targets for the nuclear power plant. These targets will be lower than the set emission limits.

As an example, table 3-7 shows the average emissions from the Loviisa and Olkiluoto nuclear power plants in 2008–2012 (STUK 2009a, STUK 2010, STUK 2011a, STUK

2012, STUK 2013b). The reactors of the Olkiluoto nuclear power plant units are of the boiling water type (BWR), with a net electrical power of 880 MW per unit (TVO 2013). Fortum’s Loviisa units have pressurized water reactors (PWR), each with a net electrical power of 496 MW (Fortum 2012). The atmospheric emissions from the nuclear power plants have been less than one percent of the set emission limits.

The radioactive gases generated in the nuclear power plant will be processed using the best available technology. The gaseous radioactive substances will be directed to a clean- ing system, where the gases are dried, delayed, and filtered using e.g. active carbon filters. Gaseous emissions can also be filtered using efficient HEPA (High Efficiency Particulate Air) filters. The decontaminated gases will be led into the atmos- phere via the vent stack. Atmospheric radioactive emissions will be monitored and measured in the several stages of the gas treatment systems, and finally at the vent stack.

Table 3-8 shows an estimate of annual atmospheric emissions of radioactive substances from the nuclear power plant.

3.16.2 Radioactive emissions into the sea

Radioactive liquids from the controlled area will be led to the liquid waste treatment plant. After treatment, the water, which contains low levels of radioactivity, will be released into the sea. The level of radioactivity of the water released into the sea will be determined using a representative sample and, additionally, by direct measurement at the outlet line before the water is led into the cooling water discharge tunnel.

The aim will be to minimize aquatic emissions, e.g. by recycling process and pool waters and by minimizing the production of waste waters.

Table 3-9 shows the average actual emissions of radio- active substances into water systems from Finnish power

Estimated emission amount, GBq/year

Tritium 3,900

Carbon-14 300

Iodines (I-131 equivalent) 0.49

Noble gases 46,000

Aerosols 0.051

Table 3-8. Estimate of annual atmospheric emissions from the nuclear power plant.

Radioactive emissions,

GBq/year Loviisa 1 and 22 x 496 MW (PWR) The emission limits for Loviisa Olkiluoto 1 and 22 x 880 MW (BWR The emission limits for Olkiluoto

Tritium 280 - 320 -

Carbon-14 300 - 820 -

Iodines (I-131 equivalent) 0.015 220 0.023 103

Noble gases 6,200 14,000,000 600 9,420,000

Aerosols 0.1 - 0.017 -

Table 3-7. Annual atmospheric emissions of radioactive substances from the Loviisa and Olkiluoto nuclear power plants, average in 2008–2012. Emission limits are established for iodine and noble gases.

80 3 Technical project description

plants in 2008–2012 (STUK 2009a, STUK 2010, STUK 2011a, STUK 2012, STUK 2013b). At the Finnish plants, tritium emissions have been about 10 percent, and the other emis- sions well below one percent, of the set emission limits. The concentration of tritium released from the nuclear power plants in sea water decreases to an insignificant level in the close vicinity of the plants.As in the case of atmos- pheric emissions, power plant-specific emission limits will be set for radioactive emissions into the water. Further- more, Fennovoima will determine its own emission limit targets, which will be stricter than the set emission limits. Pressurized water reactors utilize boric acid, which forms tritium in neutron reactions. For this reason, more tritium is released from pressurized water reactors than from boil- ing water reactors. Like other radioactive liquids, liquids containing tritium will be cleaned so that their activity level falls well below the limit values set for emissions before they are led into the water system. The radioactive liquid cleaning methods include collection in monitoring tanks and delay- ing, evaporation, ion exchange, separation of solids using mechanical filtration, slurry centrifuges, or separators.

The treatment of ion exchange resins, sludges, and other wet waste generated in the course of treatment of the nuclear power plant liquid waste is described in Section 3.12.

Table 3-10 shows an estimate of radioactive emissions into the sea from the nuclear power plant.

3.17 Conventional air emissions

3.17.1 Emissions from generation of emergency

power and heat

In the case of disturbances in the offsite grid connection, the nuclear power plant’s electricity supply will be secured using diesel generators as sources of back-up power. Fur- thermore, a gas turbine plant with a power of approxi- mately 100 MW may be built at the plant area to serve as a back-up power source for the power plant and the main grid. The supply of power to other buildings located at the

plant area and the outdoor lighting during disturbances may be ensured with diesel generators.

The emergency diesel generators will be fueled with diesel oil, and the emergency heating plant will be fueled with light fuel oil. The sulfur content of the light fuel oil will be as low as possible (not higher than 0.1 percent by mass). The burning of the fuel during the operation of the emergency diesel generators and the emergency heating plant will produce sulfur dioxide, nitrogen oxides, particles, and carbon dioxide. The use of the gas turbine will lead to small nitrogen oxide emissions. Under normal circum- stances, the emergency diesel generators, the gas turbine plant, and the emergency heating plant will only be used for test run purposes. The emergency heating plant may also be used for heat generation if annual maintenance is carried out during the winter period.

Under normal circumstances, the annual emissions from the emergency diesel generators, the gas turbine plant, and the emergency heating plant remain very small. Over a period of one year, they produce about 0.3 tons of sulfur dioxide, about 1.4 tons of nitrogen oxides, less than one ton of particles, and about 750 tons of carbon dioxide.

3.17.2 Emissions from transportation

The unit emission factors for road traffic in Finland pub- lished by VTT (VTT 2012) were used to calculate the emis- sions from transportation and commuter traffic.

The commuting distance of workers commuting from home was estimated to equal the average distance from the center of the Pyhäjoki municipality to the plant. The workers arriving from abroad or from further away in Fin- land were not assumed to return home for the weekends. The external workers working at the plant during annual maintenance were instead assumed to usually return home for the weekends. As these workers may live anywhere in Finland, their commuting distances may vary greatly. Therefore, the emissions caused by commuting will also be distributed over a wide area and thus have little impact on individual areas. For this reason, the emissions caused by commuting were in such cases calculated using the same distances that were used to calculate the corresponding val- ues for those commuting from home.

The emissions of road transportation were calculated using the same principles that were used to calculate the commuting emissions of annual maintenance workers.

Table 3-11 shows the air emissions from the transporta- tion and commuter traffic to and from the nuclear power

Radioactive emissions,

GBq/year Loviisa 1 and 22 x 496 MW (PWR) The emission limits for Loviisa Olkiluoto 1 and 22 x 880 MW (BWR) The emission limits for Olkiluoto

Tritium 17,000 150,000 1,700 18,300

Other beta and gamma 0.56 890 0.22 296

Table 3-9. Annual aquatic emissions of radioactive substances from the Loviisa and Olkiluoto nuclear power plants, average in 2008–2012.

Estimated emission amount, GBq/year

Tritium 9,100

Other beta and gamma 0.065

Table 3-10. Estimate of radioactive emissions led into the sea from the nuclear power plant.

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