The Method of Corium Cooling in a Core Catcher of a Light-Water Nuclear Reactor

Abstract

During the development of a severe accident at nuclearpower plantwith a core melting, corium is formed. One of the main barriers preventing outflow of corium into the environment is a melt localization device or a melt trap. The melt trap must accept and prevent the corium parameters from exceeding critical values, ensuring its retention in a controlled volume and cooling. For this reason, melt traps are subject to serious requirements regarding cooling methods to ensure effective containment of the melt in the core of a nuclear reactor. In the presented article, experimental studies of the interaction between corium and water, which was supplied to the surface of the corium in a melt trap for its cooling, were analyzed. As a result of the work, a number of significant problems associated with the low efficiency of this cooling method were identified, and possible ways to eliminate them were considered. A solution is proposed for optimizing the method of corium cooling in a melt trap, as well as for the scope of research on the possibility of implementing the proposed method in practice and analyzing its effectiveness using the VCG-135 test-bench and the Lava-B facility.

Analysis of Methods for Simulating the Decay Heat in Corium When Modeling a Severe Accidents at Nuclear Power Plant

“…During the melting of the reactor core, the so-called corium is formed -a melt of a radioactive mixture of uranium oxide, zirconium, zirconium oxides and steel components (products of high-temperature interaction of metals with an oxidizing medium) and other structural elements [1]. A special feature of corium is a large amount of stored energy and the presence of residual energy release due to the fact that the nuclear fuel contained in the corium continues to be a source of heat released due to the decay reactions of fission fragments of 235 U nuclei accumulated during the operation of the reactor, which allows the melt to remain in a liquid state for a long time and melt the reactor structure with its subsequent release down to the ground and groundwater [2][3].…”