新型MOX燃料组件结构尺寸对其物理性能的影响

Structure and Size Effects on MOX Fuel Assembly Physical Properties

摘要: 组件设计是反应堆堆芯设计的核心。采用蒙特卡洛方法分析了MOX燃料组件燃料棒直径和栅径比变化对组件的物理性能的影响。结果表明，MOX燃料棒直径增大，组件裂变反应率和K_eff减小，径向相对功率峰值逐渐增大而组件功率减小。组件栅径比增大，其裂变反应率、功率和K_eff先增大后减小，最大值出现在组件栅径比1.7下；组件径向相对功率峰值逐渐减小，功率分布越来越均匀。随栅径比增大，组件热中子数增加，超热中子和快中子数减小，并和UO₂燃料做了对比。

Abstract: Fuel assembly design is the key of nuclear reactor core design. In this study, Monte Carlo method was adopted for analysis of MOX fuel assembly diameter and pitch to diameter ratio effects on its performance. Results show that, with increasing of MOX fuel diameter, fission rate and K_eff decreased, relative radial power peak increased while its power decreased. With increasing of P/D, fission rate, power and K_eff increased firstly and then decreased, the highest values occurred at P/D = 1.7. Relative radial power peak deceased with increasing of P/D and it became more and more uniform. Thermal neutron increased with the increasing of P/D, while epithermal neutron and fast neutron fluxes deceased. Comparison was carried out with UO₂ fuel.