Simulation of the panda test for the ISP42 using the Cathare code

The extensive use of passive safety systems for decay heat removal proposed in some evolutionary LWR design requires an extension of the validation domain of the T/H advanced codes for the safety analysis of the future reactors. A task of the co-operation between ENEA (Italy) and CEA (France) on advanced reactors is specifically devoted to assess the capability of CATHARE (T/H best estimate French code) to simulate such systems. Within this framework ENEA and CEA took part in the CSNI International Standard Problem (ISP) 42 based on a test in the PANDA facility (PSI, CH). Phases A, C and D of the ISP were chosen by ENEA and CEA for CATHARE pre- and post-test calculations, since these phases dealt with issues already object of previous collaborations on the CATHARE assessment: pool immersed heat exchangers operating at low pressure, steam condensation in presence of non-condensable gases in tubes, coupling between primary system and containment. The results here presented concern the second part of the ISP42 performed as a post-test analysis, where the analytical model used for the first part, conducted as a double-blind exercise, has been substantially improved. (author)