Abstract A methodology for determining fission source stationarity is presented that characterizes the behavior of higher order spatial moments of the fission source distribution using Functional Expansional Tallies (FET’s). The computation of these FET’s does not require a meshing scheme like traditional methods do (e.g Shannon entropy), and is computed natively within the Monte Carlo tallying routine. To determine the efficacy of this new diagnostic, stationarity behavior is analyzed for a variety of one-dimensional and two-dimensional test cases that mimic typical reactor problems. For most problems, the results from an FET-based approach are in close agreement with those from an entropy-based approach. However, for more realistic reactor configurations with higher dimensionality and strong asymmetries, a stationary fission source distribution is better predicted using an FET-based approach.

中文翻译：

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使用功能扩展计数的平稳性诊断

摘要 提出了一种确定裂变源平稳性的方法，该方法使用功能扩展计数 (FET) 来表征裂变源分布的高阶空间矩的行为。这些 FET 的计算不需要像传统方法那样的网格划分方案（例如香农熵），并且在蒙特卡罗计数例程中本地计算。为了确定这种新诊断的有效性，我们对模拟典型反应堆问题的各种一维和二维测试案例的平稳行为进行了分析。对于大多数问题，基于 FET 的方法的结果与基于熵的方法的结果非常一致。然而，对于具有更高维度和强不对称性的更现实的反应堆配置，