Proposal for Establishing Major Monitoring Radionuclides and Lower Limits of Detection for Radioactive Effluents from the Decommissioning of Nuclear Power Plants in Korea from a Regulatory Perspective

Abstract

Kori Unit 1, the first commercial nuclear power plant (NPP) in Korea, was permanently shut downin June 2017 and is currently undergoing decommissioning. During the decommissioning process, radioactiveeffluents are generated in much the same way as they are during normal operations, and these effluents are dischargedinto the surrounding environment. This could potentially pose radiological risks to nearby residents. Therefore,monitoring these radioactive effluents is crucial for evaluating the radiation exposure doses received by residents,and it necessitates systematic management to ensure their protection. This study analyzed regulatory requirementsconcerning radioactive effluents from both operating and decommissioning NPPs in Korea and other countries. Itexamined the characteristics of effluent emissions resulting from various work processes and emission pathwaysduring the decommissioning of NPPs. The study also highlighted specific items that should be confirmed andinspected, such as emission systems and standards, for NPPs that are set to undergo decommissioning in the future. Additionally, the research categorized the major monitored radionuclides found in both liquid and gaseous radioactiveeffluents. It proposed a methodology for establishing the lower limit of detection (LLD) for the minimum detectablelevels of radioactivity concentrations of these nuclides. By applying these findings to the decommissioning of NPPsin Korea, the study aims to enhance regulatory consistency and improve the reliability of monitoring systems formanaging radioactive effluents moving forward.