Large spreading of core melt for melt retention—stabilization

For future nuclear power plants possible core melt scenarios have to be taken into account in the plant layout. Different solutions for core melt retention are proposed in the literature. The core melt retention devices should as far as possible be simple in construction, to minimize the deepness of sophistication of the physical problems connected with it and to minimize unforeseen technological problems. Furthermore it should be in good compliance with normal operational needs. One very promising solution seems to be a large enough spreading of the melt with water cooling from above. This is the favoured solution for the development of the French-German European pressurized water reactor. The technical concept and the problems to be expected in the course of an anticipated core melt accident (to be overcome in an actual design) are shown. The needs for analytical and experimental support in the early conceptual phase and later on in the design stage of plant construction are discussed. Typical analytical and first experimental results for the large core melt spreading are presented.