Simulant melt pool quench behavior via coolant injection from below

In the design of the next generation of nuclear reactors an d in the safety assessment of currently operating nuclear power plants, it is necessary to evaluate the possibility of experiencing a degradedcore accident and to identify the key strategies to follow in order to mitigate the possible consequences. In the very unlikely event of a severe reactor accident involving core melt and pressure vessel failure, it is important to identify the circumstances that would allow the molten core material to cool down and resolidify in the reactor cavity, bringing core debris to a stable coolable state (for conventional and advanced LWRs). Ex-vessel debris coolablity requires water to be present as a heat transfer medium to the ultimate heat sink over long times to achieve a stable coolable state. The interaction and mixing of high-temperature melt and water is the important technical issue in the safety assessment of water-cooled reactors to achieve ultimate core coolablity. This paper describes experiments that are currently underway to quantitatively characterize the heat transfer and flow stability conditions under which a molten pool quenches via coolant injection from below. This method of core quench and long-term debris coolability was first proposed by researchers at the Research Center in Karlsruhe and our work seeks to quantify and optimize this concept