Abstract

Based on embedded analysis, an accurate pin power reconstruction (PPR) method is proposed for conventional nodal analysis. Unlike the common form function (FF) method, the new PPR method, named the embedded pin power reconstruction (EPPR) method, directly solves a two-group fixed-source problem that is defined with pinwise homogenized group constants (HGCs) and coarse-mesh incoming partial currents on the boundary. In the EPPR scheme, the pinwise HGCs including the pinwise discontinuity factor are predetermined from single-assembly lattice calculations, and the boundary partial currents are obtained from two-step nodal analyses. Two EPPR approaches are proposed: One is a 3×3 extended color-set configuration, and the other is a smaller one considering the half-thickness of the surrounding fuel assemblies. The performance of the EPPR methods is evaluated with various benchmark problems including partially mixed oxide–loaded pressurized water reactor cores, and the results are compared with the conventional FF method. Comprehensive results of this work demonstrate that the new EPPR method can provide much better accuracy than the conventional FF-based PPR method.

摘要

基于嵌入式分析，针对常规节点分析提出了一种精确的引脚功率重建（PPR）方法。与普通形式函数 (FF) 方法不同，新的 PPR 方法称为嵌入式引脚功率重构 (EPPR) 方法，它直接解决了用引脚均质化群常数 (HGC) 和粗略定义的两组固定源问题。在边界上对传入的部分电流进行网格划分。在 EPPR 方案中，包括 pinwise 不连续因子的 pinwise HGCs 是通过单组装晶格计算预先确定的，并且边界部分电流是通过两步节点分析获得的。提出了两种 EPPR 方法：一种是 3×3 扩展颜色集配置，另一种是考虑到周围燃料组件的一半厚度的较小配置。EPPR 方法的性能通过各种基准问题进行评估，包括部分混合氧化物加载的压水反应堆堆芯，并将结果与​​传统的 FF 方法进行比较。这项工作的综合结果表明，新的 EPPR 方法可以提供比传统的基于 FF 的 PPR 方法更好的精度。