Modeling of corium melt cooling during severe accidents at the nuclear power plants

This paper is devoted to an analysis of the problem of a corium melt interaction with the water and low-melting temperature blocks in the passive protection systems against in I severe accidents at the nuclear power plants (NPP), which is of high importance for a substantiation of a nuclear power safety, for building and successful operating of the passive protection systems. In the third-generation reactors the passive protection systems against severe accidents at the NPP are mandatory, therefore the topic of this paper is of importance for the nuclear power safety. A few such systems have been considered, which are in different stage of completeness. An analysis of the unsolved thermal hydraulic problems, which solution might help to an improvement of the current systems or to a development of the new ones, more effective, has been provided. The ways for solution of the stated problems and the methods for their successful elaboration were discussed. The mathematical models developed and analysis performed in the paper might be helpful for a design of the passive systems for the corium melt retention inside the containment after a corium melt eruption from the failed reactor vessel. In the paper a problem of a mathematical modeling of corium melt coolability with the water and low-melting temperature blocks was considered. A few most successful passive systems and their characteristic thermal hydraulic problems were analyzed and discussed. The paper has shown how a modeling and computer simulation has to improve the constructions of the passive protection systems against severe accidents. The problem statement has been done for a future investigation too.