Investigation of radiation shielding of the Containment Filtered Venting System for the various operating condition

In order to prevent the uncontrolled large release of radioactive materials to the environment due to containment failure, Containment Filtered Venting System (CFVS) has been considered as the one of effective measure to prevent the containment over-pressurization. Because the filtered radioactive materials are captured and accumulated in the CFVS components, the CFVS becomes the source of the radiation and this radiation should be properly shielded to protect the field workers. In this study, the effect of CFVS operation pressure on the required shielding wall thickness is investigated in various accident scenarios. The accident scenarios considering the type of initial accident and condition of external safety injection besides the CFVS operation pressure were simulated. The source terms were obtained using the MAAP5 and ORIGEN-ARP code calculation. The effective dose rate and required shielding wall thickness were estimated by the MICROSHIELD code. Consequently, the shielding wall was necessary and the CFVS operation pressure affected the required shielding differently depending on the conditions of external safety injection. As a result, the lower operation pressure of CFVS was favorable in perspective with the low demand of shielding wall.