Study on CHF Correlation for PWR at Low Pressure Conditions Based on Stepwise Regression Analysis

摘要

Constrained by limited loop experimental data, the development of the CHF correlation for the PWR fuel assembly at low pressure conditions is a typical microscopic statistical problem with small sample, but has the requirement of high prediction accuracy. The format of CHF correlation is studied in terms of the DNB mechanism and the experimental data of the PWR fuel assemblies at low pressure conditions. A new CHF correlation is obtained using the essential variables of DNB which is suitable for low pressure conditions. Stepwise regression analysis is used to optimize the format and coefficients of the CHF correlation. BO method is used to develop the CHF correlation because it can reflect directly the original test data. A very simple switch variable has been introduced to replace the F factor for the non-uniform heat flux shape so that the complex integral calculations are greatly eliminated. The analysis and evaluation results indicate that the correlation matches well with the experimental data. This CHF correlation can be used for the prediction of DNB in the thermal-hydraulic design of PWR at low pressure conditions.