Subchannel Simulation of Rod-Bundle Two-Phase Flow Experiments with Flica5

Abstract

Flica5 is the latest CEA’s thermal-hydraulic software system for computing subchannel two-phase flow in Light Water Reactors. It embeds modified correlations from its predecessor Flica4 as well as new numerical architecture and solvers. This paper describes a simulation with Flica5 of BFBT and PSBT test series, which are reference OECD/NRC rod-bundle experimental databases. The void fractions measured during the BFBT tests are compared with the ones predicted with Flica5. A statistical method is applied in order to identify the best-fitted and most versatile closure laws. Comparisons between the experiments and the simulations show that 95 % of the discrepancies are below 4%. Both the steady-state single sub-channel and the steady-state bundle benchmarks from the PSBT tests are simulated with a certain set of closure laws in Flica5. In both cases, predicted void fractions are in good agreement with the experimental ones. Flica5 tends to underestimate the void fraction in the sub-channel cases while overestimating it in the bundle cases.