Study On Integrity Of Fuel Assembly Grid Under Seismic Loading

Nowadays,nuclear safety regulators have brewing to improve the safety requirements associated with accident conditions for the proposed nuclear power plant.For pressurized water reactors,the fuel assembly(FA)acts as a key component within the reactor,and its performance is directly related to the operational stability,safety and economy of the plant.In particular,the integrity of the fuel assembly grid,to some extent can be seen as a judge whether the fuel rods are damaged,and whether the heat can be discharged from the core.In view of this,it is necessary and urgent to study the integrity of the grid under seismic conditions.In this paper,a lateral response model is established,which is based on the analysis of the dynamic response of fuel assemblies.It makes a comprehensive discussion on the functions and characteristics of components,the analysis process of seismic conditions,the modeling of a FA and a FA row,and the establishment of design criteria.Starting from modeling of a single fuel assembly and grids at the beginning of life(BOL),the FA row model is established,which creates the conditions for the study of the integrity of grid under seismic loading.Under the premise of demonstrating that the model is reliable and the modeling process is feasible,the sensitivity analysis of the key parameters is carried out in combination with the influence of irradiation at the end of life(EOL),and the maximum impact force of the grids is simulated,which laid the foundation for the analysis of the follow-up structure design improvement and the test-based EOL analysis in the future.