Abstract
In evaluation of cooling performance for Passive Corium Cooling System, Heat removal capability depends on natural circulation flow rate. Proper selection of void fraction and two phase multiplier correlations is important to predict two phase natural circulation flow rate accurately. Evaluation method with void fraction using Ishii model and two phase multiplier using Chisholm model is developed. Predicted natural circulation flow rate compared with test results. Evaluation results with Ishii model and Chisholm model can predict accurate natural circulation flow rate in high pressure range. But natural circulation flow rate is overestimated in low pressure range. It is found from examination results that this overestimation is caused by underestimation of two phase multiplier. Change of two phase multiplier from Chisholm model to Nakazatomi model enabled accurate prediction of natural circulation flow rate in low pressure.
