STUDY ON LOSS-OF-COOLING AND LOSS-OF-COOLANT ACCIDENTS IN SPENT FUEL POOL, (1) OVERVIEW

抄録

Risk of severe accident in spent fuel pool (SFP) in nuclear power plant (NPP) which would be caused by cooling power loss or coolant water depletion was spot-lighted after the accidents in Fukushima Daiichi NPP. Effectiveness of considerable safety measures against SFP accident has to be investigated. For this purpose, it is required to improve the conventional severe accident (SA) codes so that these can be applied for SFP accident condition. In this research program, cladding oxidation model in SFP accident condition, and numerical simulation method to evaluate capability of spray cooling system which was deployed for spent fuel cooling during SFP accident, have been developed. These were introduced into the severe accident codes such as MAAP and SAMPSON, and SFP accident analyses were conducted. Analyses using Computational Fluid Dynamics (CFD) code were conducted as well for the comparison with SA code analyses and investigation of detail in the SFP accident. In addition, threedimensional criticality analysis method was developed as well, and safer loading pattern of spent fuelsin SFP was investigated.