Effects of the operating strategies of filtered containment venting system on Cesium-137 releases during severe accidents

Abstract

The concept of Filtered Containment Venting System (FCVS) has been adopted in the Republic of Korea for Pressurized Heavy Water Reactors to prevent over-pressurization of containment and to reduce the amount of radionuclides released to the environment. This strategy is considered suitable for Pressurized Light Water Reactors as well. As the effects of the FCVS on depressurization and decontamination differ, depending not only on nuclear power plant type but also on accident scenarios and venting strategies, this study analyzes the effects of FCVS operating strategies and accident scenarios on Cesium (Cs) release during severe accidents. Conservatively, the most extreme accident scenarios are chosen, namely, Station Blackout and Loss of Coolant Accident, without any mitigating measures except for the safety injection tank. Continuous and cyclic operation of the FCVS are investigated as operating strategies. In conclusion, installation of the FCVS allows the plant to meet the regulatory requirements, limiting the release of Cs-137 to under 100 TBq for limiting cases such as those considered here. Operating the FCVS to open at higher pressure in cyclic mode is found to be more effective in reducing the amount of Cs-137 release to the environment. © 2018 Elsevier Ltd