No-core-melt assessment for Canadian-SCWR under LOCA/LOECC

The safety analysis code SCTRAN for SCWR（Super Critical Water Reactor） is modified to own the capability to assess the radiation heat transfer with developing a two-dimensional heat conduction solution scheme and incorporating a radiation heat transfer model. The verification of the developed radiation heat transfer model is conducted through code-to-code comparison with CATHENA. The results show that the modified SCTRAN code is successful for that the maximum absolute error and relative error of the surface temperature between results of SCTRAN and CATHENA are 6.1℃and 0.9%, which are acceptable in temperature prediction. Then,with the modified SCTRAN code, the loss of coolant accident with a total loss of emergency core cooling system（LOCA/LOECC） of Canadian-SCWR is carried out to evaluate its ＂no-core-melt＂ concept. The following conclusions are achieved： 1） in the process of LOCA, the decay heat can be totally removed by the radiation heat transfer and the natural convection of the high-temperature coolant, even without an intervention of ECCS（Emergency Core Cooling System）; 2） The peak cladding temperature of the fuel pins in the inner and outer rings of the high power group are 1236℃ and 1177℃ respectively, which are much lower than the melting point of the fuel sheath. It indicates that the Canadian-SCWR can achieve ＂no-core-melt＂ concept under LOCA/LOECC.