Two core catcher concepts for innovative future PWR containments

To obtain a generally accident-resistant containment, intensive investigations have been initiated at Kernforschungszentrum Karlsruhe, Germany. The main objective is to derive upper limits of containment loads resulting from energetic severe accident phenomena rather than to design a new containment in detail. This paper concentrates on current R D activities related to ex-vessel core melt cooling in a PWR containment. To satisfy the integrity, two problems have to be solved: (a) remove the decay heat from the corium and (b) remove the decay heat from the containment, by passive mechanisms if possible. The basic idea for passive decay heat removal from the melt is to create a large surface for heat transfer to the coolant. With this in mind, two different core catcher concepts have been developed that are described in this paper.