A method for determining the heat transfer and drying point of a debris bed after a serious accident of a sodium cooled fast reactor

Abstract

A method for determining the heat transfer and drying point of a debris bed after serious accident of sodium-cooled fast reactor features that boundary conditions of debris bed aft serious accident ofreactor are determined and grid is divided according to energy equation of temperature distribution. Then the equivalent thermal conductivity of the debris bed is calculated for the non-boiling state, boiling state and drying state respectively. Then, the equivalent thermal conductivity of the debris bed in the channel region where the debris particles are cracked by steam extrusion is calculatedwhen the debris bed is superheated locally. Finally, the initial conditions and boundary conditions are set to calculate the next time step temperature and the equivalent thermal conductivity of eachgrid, and the temperature distribution of the debris bed and the location of the drying point at each time point are finally obtained. A simple equivalent thermal conductivity model is used to calculate the complex energy transfer process in the debris bed, and the equivalent thermal conductivity of the debris bed adopts different calculation modes according to different working conditions, and finally the temperature distribution at each time in the cooling process of the debris bed of the sodium-cooled fast reactor and the position of the debris bed drying point when the cooling is insufficient are obtained.

Description

technical field [0001] The invention belongs to the technical field of fragment bed heat transfer and safety analysis after a serious accident of a nuclear reactor, and in particular relates to a method for determining heat transfer of a fragment bed and a dry point after a severe accident of a sodium-cooled fast reactor. Background technique [0002] The analysis of the heat transfer characteristics of the fragment bed is one of the keys to the study of the behavior of the sodium-cooled fast reactor after a severe accident. The heat transfer capacity, temperature distribution of the fragment bed and the heat flux prediction in the dry state are of great significance to the mitigation and prevention of severe accidents. [0003] There are mainly two ways to analyze and study the heat transfer characteristics of a fragment bed: experimental research and numerical simulation. So far, due to the limitations of experimental funds and experimental conditions, there have been few ...

AI Technical Summary

Problems solved by technology

So far, the more common severe accident analysis programs such as MAAP, MELCOR, etc. are used to calculate the entire severe accident sequence, and most of them include the cooling analysis and calculation module of the core debris bed under severe reactor accidents, but the calculation models are relatively simple and cannot analyze the debris in detail bed cooling process

The French Institute of Radiological Protection and Nuclear Safety (IRSN) developed the MC3D program, which was first proposed by Berthoud and Valette et al. in 1994. It uses a transient three-dimensional four-equation model. The MC3D program uses a general thermodynamic equilibrium assumption and can be used for the calculation of the cooling characteristics of the debris bed. And the prediction of dryout, but the working conditions after dryout cannot be calculated

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