DESIGN OF CONTAINMENT FILTERED VENTING SYSTEM FOR DEPRESSURIZATION IN CONTAINMENT UNDER SEVERE ACCIDENTS

摘要

This study investigates the effect of the Containment Filtered Venting System (CFVS) on the depressurization in the containment building under severe accidents. When the pressure in the containment reaches the setting pressure that should be below the design pressure of the containment, substantial steam and gases with high temperature could be vented into scrubbing water in the CFVS, and then the pressure in the containment could be decreased. MELCOR was used to estimate the depressurization in the containment with the operating of the CFVS during a severe accident. The Korean Standard Nuclear Power Plant (KSNP) was chosen as the target plant. The accident scenario to simulate the pressure increment in the containment is a Station Blackout. The calculation results, i.e., the pressure variation in time, were explained by the thermal hydraulic phenomena in the containment and the CFVS. The evaporation of scrubbing water in the CFVS for a long operating time was found as one of the design problems. To expand the evaporation time of a pool in the CFVS, the effect of the exhaust pipe size at the outlet of the CFVS on the evaporation and the depressurization was examined to optimize the design of the CFVS for a long operating time.