Nuclear reactor serious accident fragment bed melting process simulation method based on particle method

Abstract

A nuclear reactor serious accident fragment bed melting process simulation method based on a particle method comprises the following steps of 1, conducting particle modeling, setting particle initialarrangement and parameters, using particle clusters for representing solid fragments, and numbering the particles and the fragments respectively; 2, dividing background grids, and retrieving neighborparticle groups; 3, explicitly calculating a viscosity item, a surface tension item and a gravity item in the momentum equation, and estimating particle speed and displacement; 4, calculating particlepressure by adopting a Poisson equation, and correcting particle speed and displacement according to a pressure gradient model; 5, calculating a particle enthalpy value, a temperature and a phase state; 6, calculating the translation speed and the rotation speed of the fragments, and correcting the speed and the displacement of the solid-phase particles in the fragments; 7, outputting a calculation result. According to the method, small-scale particles are used for representing large-size solid fragments and numbering the large-size solid fragments, so that the identification problem of the fragments to which the particles belong is solved. In addition, a radiation heat exchange model between the solid fragments is established according to a mode of judging whether two particles are shielded by other particles or not.

Description

technical field [0001] The invention relates to the technical field of research on the melting process of debris beds in severe accidents of nuclear power plants, in particular to a method for simulating the melting process of debris beds in severe accidents of nuclear reactors based on a particle method. Background technique [0002] In severe nuclear accidents, the core loses cooling. As the core temperature rises, metal materials such as fuel cladding, spacer grids, and control rods melt first due to eutectic reactions, and the melt penetrates downward. The temperature continues to rise, and the oxides such as fuel pellets are gradually melted by the metal melt at a temperature lower than the melting point of their respective components. The fuel pellets, metal components, and melts condense, pulverize, and disintegrate during the cooling process, and accumulate in the form of fragments, which is called a fragment bed. Debris beds can exist in the core region, pressure v...

AI Technical Summary

Problems solved by technology

The present invention proposes a method for simulating the melting process of nuclear reactor severe accident debris bed based on the particle method. The method uses small-scale particles to represent larger-sized solid debris, which improves the calculation accuracy. At the same time, by numbering each solid debris, Resolved an issue with the identification of solid fragments to which a particle belongs

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