As of 2023, there are a total of 24 nuclear power plants (NPPs) in operation in Korea, with 21 pressurized water reactors (PWRs) and three pressurized heavy water reactors (PHWRs). Korean NPPs discharge radioactive effluents into the environment every year. Radioactive effluents from NPPs contain various radionuclides and materials, including 3H, 14C, Noble gas, particulates, and iodine Among the radioactive effluents discharged from Korean NPPs, 14C is a pure beta emitter with a half-life of 5,730 years. The human body can inhale and ingest 14C to cause internal exposure. In addition, the amount of 14C present in the environment is decreasing, but the amount of 14C discharged from NPPs is increasing. 14C discharged to the environment can be inhaled and ingested by the public around NPPs through various pathways. For this reason, it is very important to monitor and manage 14C because it affects the dose of the public around NPPs. Therefore, this study compared and analyzed the average emissions of 14C discharged from PWRs and PHWRs during the recent 10 years (2012-2021). An average of the public dose due to 14C released from NPPs depending on the reactor types from 2012 to 2021 was also compared. It is inevitable to discharge radioactive effluents while operating NPPs. Korea Hydro & Nuclear Power (KHNP) manages and monitors radioactive effluents released into the environment. According to a survey and analysis of 14C discharged from PWRs and PHWRs and the average dose of the public over the recent 10-year (2012-2021) around Korean NPPs, 14C released from PWR accounted for 3.1% of the total discharge but accounted for more than 93.67% of the total public dose. In addition, 14C discharged from PHWRs accounted for 1.12% of the total discharge, but its resulting dose to the public accounted for more than 83.87% of the total public dose. As a result of analyzing the public dose due to 14C from 2012 to 2021, it was gradually increasing every year. Based on these results, monitoring and managing 14C discharge and its resulting doses to the public are important in the future.

Kori Unit 1, Korea’s first commercial nuclear power plant is preparing to dismantle after 40 years of power supply. However, unlike the public dose assessment for nuclear power plants in operation, the dose assessment for the public due to abnormal events during the decommissioning of nuclear power plants is insufficient. Therefore, in this study, the steam generator chamber is selected as hypothetical events target among metal waste, which is a major radioactive material generated during the decommissioning of nuclear power plant. In addition, the possible abnormal event scenarios and effective does to public in the Exclusion Area Boundary due to the released radioactive materials are predicted during the disassembly and transportation of the steam generator. For the source term that can be released during the dismantling of the steam generator, the inventory of each radionuclide is evaluated based on the smear test results of the steam generator replaced in Kori Unit 1 in 1998. To evaluate the diffusion of radioactive material, the atmospheric dispersion factor (χ/Q, sec/m3) is calculated through the PAVAN code of the US NRC using the meteorological data of the Kori nuclear power plant for 3 years from 2019 to 2021 according to IAEA recommendations. For the assessment of the public dose, the external dose coefficient and inhalation coefficient of the ICRP and the inhalation rate of the NRC Regulatory Guide 1.3 are referred. It is confirmed that the effective dose to the public in the Exclusion Area Boundary due to the abnormal event during the dismantling of the steam generator is much lower than the effective dose standard value of 250 mSv for 2 hours after the event in the Exclusion Area Boundary.