Comparisons of REXCO code predictions with SRI SM-2 experimental results

SRI International has performed a series of simple model (SM) experiments for the Clinch River Breeder Reactor Project (CRBR). The SM tests consisted of five experiments. The energy source used to simulate the core-disassembly accident loads was a PETN-microsphere mixture, which was well calibrated. These experiments were well instrumented and performed under carefully controlled conditions. The experimental data can be used as reliable test data for validation of computer codes, as well as the modeling technique used in the computer analysis. This paper deals with the REXCO-HEP code predictions of the SRI SM-2 test, which was a dynamic test performed on 1/20th scale model of the CRBR. Two calculations have been performed: one used the pressure history P(t) of the core detonation products as input, and the other the pressure-volume relation (P-V) of the detonation products as input. The pressure loadings and wall deformations obtained with the P(t) calculations are in better agreement with the experimental measurements than those obtained with the P-V calculations. This is because the P-V relations used in the code calculation were derived from the pressure gauge readings of the core gas, the measured surface motions of the slug and the calculated compressibility of the coolant; they may become less accurate at low pressures. Therefore, in performing code validation calculations, the pressure history of the core gas should be used in the analysis to describe the behavior of the core gas, if the P(t) values are available from the experimental data