This thesis, “Simulation of CABRI loss-of-flow experiments with the TRACE/FRED codes”, is a result of cooperation with IRSN (France), who transferred to PSI the CABRI facility specification and test data. The thesis has mainly two aims: reaching a further validation of the TRACE code for two-phase sodium, currently being performed at Paul Scherrer Institut, and analyzing the fuel behaviour during the transients with the FRED code. The calculations were using coupled TRACE and FRED in frames of the FAST code system. A pure loss-of-flow transient (LOF) and two LOFs followed by transient overpower (TOP) were simulated. Several correlations for critical heat flux (CHF) and post dry-out heat transfer coefficient were implemented and tested in order to achieve a suitable initial model for these phenomena. It was the very first step towards sodium dry-out modelling in the modified version of TRACE. Both thermal-hydraulic and fuel thermal-mechanics results were compared with those provided by the CABRI Project report, and even some benchmarking against other codes was performed.

Outgoing