Analysis of PSBT Benchmark Exercises for Void Distribution and DNB Using a Subchannel Code MATRA

Abstract

In the framework of OECD/NRC PSBT benchmark, the subchannel grade void distribution data and DNB data were evaluated by a subchannel code MATRA. The zone-averaged void fraction at the central region of the 5x5 test bundle was compared with the benchmark data. Optimum values of turbulent mixing parameter, which is an input parameter for MATRA code, were evaluated by employing subchannel fluid temperature data. The influence of mixing vanes on the subchannel flow distribution was examined through a CFD analysis. The steady-state DNB benchmark data with uniform and non-uniform axial power shapes were evaluated by several DNB prediction models including an empirical correlation, CHF lookup table, and representative mechanistic DNB models with subchannel cross-sectional averaged local properties.