超临界水混合堆快谱区组件物理-热工性能分析

Neutron-Kinetics/Thermal-Hydraulics Performance Analysis of Fast Zone Assembly in Supercritical Water Reactor Mixed Core

提出超临界水混合堆快谱区多层燃料组件设计方案。用MCNP与STAFAS程序对多层燃料组件进行初步的中子物理与热工水力性能分析,同时对组件结构参数(栅距与棒径比P/D)进行敏感性研究。结果表明:快谱多层燃料组件设计不仅能够实现核燃料的增殖,且可获得较大的负冷却剂温度反应性系数与燃料温度反应性系数;减小P/D均可提高燃料的转换比,但较小P/D会导致核热点因子增大。适当调整组件裂变区燃料富集度可有效改善组件裂变区轴向功率不均匀性,降低核热点因子。

This paper proposes a multi-layer design of fuel assemblies for the fast zone of the SCWR （supereritieal water reactor） mixed core. Both neutron-physical and thermal-hydraulic behavior of the multi-layer fuel assembly were analyzed using the MCNP code and the sub-channel analysis code STAFAS, respectively. Besides, the sensitivity analyses of some parameters such as pitch-to-diameter were investigated. The results show that with the proposed multi-layer structure, the fast zone of the mixed core has breeding capability and gets a negative void reactivity coefficient of coolant; a smaller pitchto-diameter leads to a higher conversion ratio, however, it also results in a higher nuclear spots factor. It is possible to adjust Pu enrichment for improving axial power uniformity effectively and decreasing nuclear soot factor in seed fuel assembly.