In-vessel hydrogen production assessment during severe accident sequences

In 1991 the Design Division of Electricite de France (EdF) acquired the MAAP license (modular accident analysis program) to contribute to the assessment of severe accident concerns both on its 56 operating (EdF) pressurized water reactor (PWR) plants (including two N4 plants), and for future projects, mainly the European pressurized reactor (EPR). EdF checked the MAAP code consistency with CATHARE (until the beginning of core overheating) and ESCADRE (severe accident code system of CEA-IPSN, the technical support of the French Safety Authority) results, mainly on thermal-hydraulic aspects. This paper presents results on studies concerned with the MAAP4 code simulation of hydrogen production during severe accidents and the resulting core degradation phase on a French four-loop 1300-MW PWR.