Abstract The present paper is concerned with the extension of the treatment of the scattering anisotropy developed in the AN-SPN (or simply AN) method up to the approximation of the second order. To assess such extension, two 3D examples are considered: the first one is an axial piece of a 17×17 PWR MOX assembly containing the heads of control rods; while the second example is related to a 3D reactor core containing UO2 and MOX homogenized assemblies. It is shown that the passage from the isotropic to the linearly anisotropic approximation of the differential scattering cross section turns out into a remarkable improvement of the results, as regards the multiplication factor as well as the flux distribution. For the kind of problems like those here considered, less important is, on the contrary, the extension to the second order of the anisotropy, although such an upgrade may be included in the calculation with only an almost negligible effort, owing to the irrelevant impact on the computing time.

中文翻译：

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关于散射各向异性与低阶输运方法的相关性

摘要 本文涉及将 AN-SPN（或简称 AN）方法中开发的散射各向异性处理扩展到二阶近似。为了评估这种扩展，考虑了两个 3D 示例：第一个是包含控制棒头的 17×17 PWR MOX 组件的轴向件；而第二个示例与包含 UO2 和 MOX 均质组件的 3D 反应堆堆芯有关。结果表明，从微分散射截面的各向同性近似到线性各向异性近似，结果显着改善了结果，就倍增因子和通量分布而言。对于像这里考虑的那些问题，不太重要的是，相反，各向异性的二阶扩展，