원전종사자 피폭에 기여하는 선원항 고찰 및 감마상수를 활용한 방사선원항 간략 산출에관한 연구

Abstract

In domestic nuclear power plants (NPPs), the materials used for reactor coolant pipes and steamgenerators are largely similar, which means the sources of radionuclides generated during their operation can alsobe similar. The primary sources of radionuclides are fission products and corrosion products. Identifying a universalradionuclide source that contributes to worker exposure can help optimize exposure management for workers. Toconfirm the radionuclide sources, the behavior of radionuclides based on the operational status of the NPP wasanalyzed in the final stability analysis report. This report also identified the current status of major radionuclides forcontamination management and worker exposure management at both domestic and international nuclear facilities. As the operation of NPPs continues over time, steam generators are being replaced. The radionuclides present inthe steam generators exhibit similar behavior over a certain period. Consequently, the radionuclide sources in thesteam generators and reactor coolant pipes were inferred from the distribution of those identified during steamgenerator replacements. Seven radionuclides were identified as the major contributors to radiation exposure forworkers in NPPs: 137Cs, 60Co, 58Co, 51Cr, 95Zr, 54Mn, and 59Fe. Additionally, measuring radiation sources at NPPs isquite challenging. If we can express a derived nuclide that contributes to exposure simply based on measured doses,it would be beneficial for worker exposure management and radioactive waste transport management. To achievethis, we derived a straightforward formula, referred to as the ‘dose-radionuclide source’ term, which calculates theexposure contribution by inversely relating the measured dose from a radiation meter to the gamma constant.