Interpretation of TRIGA reactor experimental data with SIMMER-III code for RELAP5 model evaluation and transient analysis

The experimental data obtained in a test campaign carried out in the TRIGA reactor of ENEA/Casaccia are being used to validate a coupled RELAP5/PARCS numerical model for the thermal-hydraulic and dynamic simulation of the reactor. The tests conducted at different power levels provided the temperature measurements at the core inlet and outlet that allow the evaluation of DT through the core at different radial positions. In order to interpret the experimental data for the evaluation of total water mass flow rate through the core in natural circulation, several calculations have been performed with the SIMMER-III code (CFD two-dimensional code) at different core power levels trying to reproduce the experimental measurements. The results of SIMMER-III code were used to fit and validate the simplified 1-D model of the RELAP5 code used for thermal-hydraulic transient analysis of TRIGA reactor. Finally, this paper presents the interpretation of some reactivity transients using this improved T/H model with the RELAP5 point-kinetics neutronic model. (author)