Prediction of Heat Removal Performance for Passive Containment Cooling System using MARS-KS Code Version 1.14

To protect the containment integrity against such as the prolong SBO, many different type of the passive containment cooling systems (PCCS) has been developed in many countries. AP1000 has steel containment which resides inside of a concrete structure with ducts that allow cool outside air to come in contact with the outside surface of the steel containment vessel. AP1000 PCCS cools outer surface of steel containment shell using natural circulation of air and water evaporation. ESBWR has the heat exchanger type of PCCS condenser. The PCCS condensers are located in a large pool (PCC pool) positioned above, and outside the containment. PCCS loops receive a steam-gas mixture supply directly from the containment. The heat removal process made by the internal condensation in the PCCS condenser located in PCC pool. Prediction of performance of the conceptual PCCS is conducted using MARS-KS code version 1.14. Key thermo-hydraulic phenomena are identified in this paper. - Flashing phenomena dominate in the phase change and the loss of inventory in PCCT. - Due to this, natural circulation flow is changed from single phase natural circulation mode to two phase natural circulation mode. - Containment pressure is re-pressurized by the loss of subcooling in the PCCT water. - Containment status can be divided as distinguishable periods related with the PCCS status. Design considerations are also identified to enhance the performance of PCCS against postulated accidents. - It needs idea that can improve the performance of the PCC heat transfer innovatively. - Fin-type tubes and inclined tube type of PCCS design are considered.