Method of characteristics (MOC) for solving neutron transport equation based on unstructured mesh has already become one of the fundamental methods for lattice calculation of nuclear design code system. However, most of MOC codes are developed with flat source approximation called step characteristics (SO scheme, which is another basic assumption for MOC. A linear source (LS) characteristics scheme and its corresponding modification for negative source distribution were proposed. The OECD/NEA C5G7-MOX 2D benchmark and a self-defined BWR mini-core problem were employed to validate the new LS module of PEACH code. Numerical results indicate that the proposed LS scheme employs less memory and computational time compared with SC scheme at the same accuracy.%基于非结构网格的中子输运方程特征线解法已成为堆芯设计程序中组件输运计算的标准方法之一.但现有的大部分特征线法程序均是基于平源近似的步特征线法模型开发的,平源近似是特征线法中除角度变量直接离散外又一基本假定.本工作提出一种基于线性源近似的中子输运方程特征线解法,并提出相关负中子源分布的修正方法.采用自行研制的数值计算软件PEACH,对OECD/NEAC5G7-MOX 2D基准问题和自定义沸水堆小堆芯问题进行检验.数值计算结果表明,本工作提出的线性源近似特征线法模型在相同计算精度的前提下,占用更少的系统内存和运行时间.
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