Accident analyses and passive measures reducing the consequences of a core-melt in CAPRA/CADRA reactor cores

As part of the Combustion Amelioree du Plutonium dans les Reacteurs Avances /Consommation D'Actinides et de Dechets dans les Reacteurs Avances (CAPRA/C ADRA) program the feasibility of reactor systems with different neutron spe ctra and coolants is investigated to burn plutonium and also to destruct mi nor actinides and long lived fission products. In this paper, we deal with reactor cores with fast spectrum and metal cooling. The design of this type of CAPRA/CADRA cores shows significant differences compared e.g. to conven tional fast reactor cores. The high Pu-enrichment and the high minor actini de load have an important influence on the core meltdown behavior and the a ssociated recriticality risk. To cope with this risk, inherent design featu res and special measures/devices are investigated for their potential of ea rly fuel discharge to reduce the criticality of the reactor core. An assess ment of such measures/devices, which could provide an additional line of de fense against severe accident development, is given. Within the CAPRA/CADRA program, also accelerator driven subcritical systems are investigated for performing the task of transmutation and incineration. In these fast neutro n systems with a strong external neutron source, the kinetic behavior is di fferent to a critical core and new strategies and measures for accident pre vention have to be investigated. (C) 2000 Elsevier Science B.V. All rights reserved.