열수력 기기해석 코드 CUPID를 이용한 저압 미포화비등 해석

Abstract

Subcooled boiling is an important phenomenon for the design, operation and safety analysis of nuclear power plant. However, the existing safety analysis codes have some weaknesses in predicting subcooled boiling phenomena at low-pressure conditions since they incorporates the wall boiling model developed at high-pressure conditions. Thus, it is required to improve the predictive capability of thermal-hydraulic analysis codes on subcooled boiling phenomenon at low-pressure conditions. In this study, a couple of subcooled boiling experiments at high- and low-pressure conditions are analyzed using a three-dimensional thermal-hydraulic component code, CUPID. The CUPID code was applied to the experiment of Christensen and Bartolomey performed at high-pressure conditions, and it was shown that the CUPID code can provide a reliable prediction on the propagation of the void fraction. However, the simulation results of CUPID showed considerable discrepancies from the experimental data of Zeitoun and SUBO test obtained at near-atmospheric pressure when the default wall boiling models were used. The sensitivity analysis of submodels in the heat partitioning model was performed to evaluate the parametric effect of major factors on the void fraction distribution and to find the optimized sets of submodels for low pressure conditions. Then, the modified models of the CUPID codes are applied to perform the preliminary analysis of the JNU subcooled boiling facility.