ANALYSIS OF UMSICHT WATER HAMMER BENCHMARK TESTS: RESULTS FROM PSI USING TRACE AND RELAP5 CODES

摘要

The capabilities of the nuclear system transient codes TRACE and RELAP5 to model coupled two-phase flow and pressure wave propagations in a piping system with a spatially one-dimensional approximation are assessed by analyzing the first few seconds after valve closure in the UMSICHT PPP cavitation water hammer experiment 329. The relevance of increased condensation heat transfer (beyond code base case parameters) for accurate modeling of the pressure peaks has been demonstrated. The first vapor generation, timing and spiky shape of the first pressure peak, and the timing of the following peaks are very well captured by both codes when appropriate enhanced condensation parameters are used, while experimental broadening and damping of the following pressure peaks by Fluid-Structure Interaction (FSI) of the flow with vibrations of the piping structure are not contained in the modeling results. Using these codes for more accurate prediction of cavitation water hammer behavior requires further development work.