Abstract
In vessel retention (IVR) is an important severe accident mitigation strategy. Currently some study is based on twolayer melt pool configuration assumption. However, MASCA experiment indicates that in some case heavier metallic layer containing dissolved uranium may be formed beneath traditional two-layer configuration. For three-layer configuration, heat flux distribution might be changed. Thus three-layer configuration needs to be analyzed. However, some of current code is not capable to simulate this threelayer configuration. While others proposed three-layer models are different from each other. In order to perform IVR analysis based on three-layer configuration, a new modular IVR analysis code is developed and verified based on C++. Results show that the developed code has a good agreement with the data from literature. Thus the developed code is applied to perform IVR analysis based on three-layer configuration. Based on simulation results, compared to twolayer configuration, heat flux at the bottom of the vessel and light metallic layer are notably increased in three-layer configuration. According to sensitivity analysis, within the scope of this study, CHF ratio remains below unity in all the cases. Besides uranium oxidation rate and total mass of stainless steel have larger influence on heat flux distribution and maximum CHF ratio.
