Since the Three Mile Island accident in 1979, a worldwide effort has been undertaken to understand and to model severe accident phenomena in nuclear reactors in case of a hypothetical loss of core cooling. ICARE/CATHARE (Chatelard et al, 2000) is a system code developed by the French “Institut de Radioprotection et de Sûreté Nucléaire” and devoted to Nuclear Power Plants calculations. Since 1996, the capabilities of the ICARE2 V3 code, the module describing core degradation phenomena, have been significantly extended to cover the late phase of the core degradation process. The assessment has been done against “in pile“ experiments performed in ACRR by Sandia National Laboratory (DC1, MP1 and MP2) and in Phebus reactor by IRSN in 1999, (FPT-4). The Scarabee BF1 test, performed in 1985 at Cadarache, has been used, to validate models dealing with the natural convection inside the molten pool, considering a specific model instead of a simple correlation based on an equivalent thermal conductivity.
(1) : ENEA (Ente per le Nuove Tecnologie l’Energia et l’Ambiente)
(2) : IRSN