Analysis of PHEBUS FP and QUENCH Tests with ICARE2 Code and Comparison with SCDAP/RELAP5 Code Results

In the framework of the participation in the PHEBUS FP experimental program and the 4th Framework European Investigation of Core Degradation (COBE) project, the analysis of PHEBUS FP and QUENCH tests have been performed using both ICARE2 V2 MOD2.2 and SCDAP/RELAP5/MOD3.1 codes. The analysis concerned post-test and pre-test calculations for FPT-1 and FPT-2 PHEBUS FP experiments, and post-test calculations for QUENCH-01 experiment performed in the QUENCH test facility at FZK-Karlsruhe. FPT-1 calculations show the capability of the codes to reproduce reasonably well the bundle temperature behaviour and the generation of hydrogen during the experimental transient. Main reasons for discrepancies in the two code results have been identified. The computation of the late degradation phase is much more uncertain. Pre-test calculations for FPT-2 show the attainment of reducing conditions as expected in the test specifications. Significant bundle degradation is predicted by the two codes during the early degradation phase. The late degradation phase is predicted by SCDAP/RELAP5 well in advance with respect to ICARE2. Post-test ICARE2 calculation for the QUENCH-01 experiment shows the ability of the code to well reproduce bundle temperature behaviour and hydrogen generation during the preoxidation and transient phase before quenching. The local shattering model available in SCDAP gives reasonable prediction of hydrogen generation during quenching.