空间离散对弥散颗粒燃料燃耗计算的影响

Influence of Spatial Discretization on Burnup Calculation of Dispersed Particulate Fuel

单栅元燃耗计算是全堆芯燃耗计算的基础,栅元空间离散对燃耗计算的结果有显著影响。弥散颗粒燃料由于双重非均匀性的存在,空间离散的情况更为复杂。本文基于ALPHA组件程序,分析了颗粒在平源区上归类的宏观离散方案与颗粒内部细分燃耗区的微观离散方案对弥散颗粒燃料燃耗计算的影响。算例包括无毒物的UC颗粒单栅元,含Gd_(2)O_(3)层的QUADRISO颗粒单栅元和含UC颗粒与Gd_(2)O_(3)毒物颗粒的双颗粒单栅元。数值结果表明,无毒物栅元宏观需分3圈以上,含Gd_(2)O_(3)栅元宏观需分5圈以上;无毒物算例微观不需要分圈,含Gd_(2)O_(3)层的QUADRISO颗粒需在微观燃料区细分2圈,双颗粒问题的Gd_(2)O_(3)毒物颗粒微观需分12~15圈。

Pin cell burnup calculation is the basis of the whole core burnup calculation.The spatial discretization of burnup region has significant influence on the accuracy of burnup calculation.The spatial discretization of dispersed particulate fuel is more complicated due to the double heterogeneity.Based on the lattice physics code ALPHA,the effect of macroscopic discretization at pin level and microscopic discretization at particle level was analyzed.Cases included UC particle pin cell,Gd_(2)O_(3)-layered QUADRISO particle pin cell and a double-particle pin cell filled with Gd_(2)O_(3)particles and UC particles.The numerical results show that case without poison should set at least 3 macroscopic burnup regions while cases with Gd_(2)O_(3)need at least 5 macroscopic burnup regions.No microscopic discretization is required for case without poison.QUADRISO particle containing Gd_(2)O_(3)layer should set 2 microscopic burnup regions in the fuel region,and the Gd_(2)O_(3)particle of double-particle cell need 12-15 microscopic burnup regions.