Improvement of the subcooled boiling model for thermal–hydraulic system codes

Abstract

In thermal–hydraulic system codes, such as MARS and RELAP5/MOD3, the Savannah River Laboratory (SRL) model has been used as a subcooled boiling model for recent two decades. However, it has been known that the SRL model cannot properly capture the effects of liquid velocity and channel diameter on the development of axial void profile. The authors suggested the modifications of the SRL model in the previous studies, focusing on the net vapor generation model and the wall vapor generation model, and validated the modified model using 103 subcooled boiling experiments, of which pressures were limited up to 69 bar.In this work, the previous subcooled boiling model has been further improved for its extension to high-pressure conditions up to ∼ 150 bar using additional 42 sets of high-pressure experiments. The new model has been validated against a wide range of experiments. It was shown that the new model predicts axial void fractions better than the SRL model and the previous model for the whole pressure range and that it can completely replace the SRL model without any limitation.