Research on Control Rod Cuspate Effect with Grid Spacer

When calculating control rod effect with node method, the improper treatment will lead control rod worth to form cuspate effect. In this paper, the three-dimensional simulation was simplied to one-dimension. Three different handing methods (volume-weighted method, axial volume-weighted method and axial volume-weighted method with discontinuous factor) were applied to correct control rod cuspate effect in different conditions (with grid spacer and without grid spacer). The comparison of these simulation results shows that the grid spacer can bring error to the simulation results, and the better method to get homogenization cross section is used. Besides, adding axial discontinuous factor for calculation can reduce error obviously.