燃料组件弯曲的高保真全堆芯中子学计算方法及应用

In order to study the influence of bowing deformation of fuel assemblies on core power distribution, this paper proposes an equivalent method for simulating the bowing of fuel assemblies in PWR Core. That is, according to the principle of conservation of atomic number of the water gap material around the fuel assembly before and after bowing, the nuclear density of all nuclides in the water gap after bowing is changed by keeping the width of the water gap unchanged before and after bowing, which approximates the change of the water gap around the equivalent fuel assembly after bowing. Its correctness is verified by Monte-Carlo code NECP-MCX and deterministic numerical code NECP-X. Based on the deterministic numerical code NECP-X, the fuel assembly bowing condition of the EPR core is simulated and analyzed. The calculation results show that due to the change of local moderating effect, the small bending of fuel assembly has a relatively great influence on the core power distribution. When the maximum offset in the whole core problem is about 2mm, the relative change of the assembly power can reach about 5%.