TVO and the personnel of the Company are in all radiation protection activities committed to the ALARA principle (as low as reasonably achievable). According to the principle, individual and collective radiation doses are kept as low as possible by practical measures.
The limitation of the doses and keeping radioactive emissions as low as possible are taken into account already at the design stage of structures and functions. Every employee shall consider factors that influence radiation protection in their own work. The development of radiation protection activities is based on regulatory guidelines, and also on international recommendations.
The radiation doses of everyone working in the controlled area of the nuclear power plant are monitored and measured using dosimeters. According to Section 3 of the Radiation Decree in Finland, the effective dose caused to a worker by radiation work shall not exceed an average of 20 mSv per year reckoned over a period of five years, nor 50 mSv in any one year. TVO’s own goal regarding individual doses is that the annual dose shall not exceed 10 mSv per year for anybody working in Olkiluoto and the doses caused by internal contamination shall not exceed the value of 0.5 mSv. These goals have also been achieved.
New radiation protection legislation entered into force on 15 December 2018. The dose limits set in the new law are stricter than before. In 2018, the radiation doses remained below the limit values set in the new law.
Radiation exposure under dose limits
The radiation exposure of employees in Olkiluoto has been low, remaining clearly below the dose limits specified by the authorities. In 2018, the total dose of employees subject to radiation exposure was 1 101 man-mSv. A total dose of 918 man-mSv was accumulated during the power plant’s annual outage.
The combined radiation dose of TVO’s own personnel was 250 (2017: 210) man-mSv, and that of external personnel 851 (2017: 740) man-mSv. The highest individual annual dose incurred at the Olkiluoto nuclear power plant was 9.49 mSv. The number of employees covered by dose monitoring was 4,324 (2017: 3,350), and the doses of 1,226 (2017: 1,167) persons exceeded the recording limit. The average annual radiation dose received by a person living in Finland from environmental radiation sources is approximately 3.2 mSv.
Environmental radiation exposure under extensive monitoring
Environmental radiation safety is at the Olkiluoto nuclear power plant monitored on a regular basis with many different methods and through the cooperation of several parties. TVO has set up seven continuous radiation dose rate measurement points in the plant area and ten in the surrounding region. These automatically report their results as well as any alarms to both the Olkiluoto plant units and the Radiation and Nuclear Safety Authority (STUK). TVO has installed four air samplers and eleven dosimeters in the immediate vicinity of Olkiluoto. The sampler filters are analysed for radioactivity every 1–4 weeks. The dosimeters are read four times a year. In addition to these, TVO carries out extensive measurements in the plant area twice a year, and uses portable measurement equipment to perform work-specific radiation monitoring when necessary.
The people living in the environment of the nuclear power plant are once a year measured in Olkiluoto in STUK's mobile full-body scanner unit. TVO reports the results of radiation safety monitoring carried out in the plant environment to environmental and radiation safety authorities.
In measurements conducted by STUK on the local residents, no radioactive nuclides originating from the plant were detected.
