蒙卡程序重复结构识别和展开方法研究

Research on the Method of Identifying and Unfolding Repeated Structures in Monte Carlo Program

摘要: 重复结构给核反应堆蒙卡程序几何建模带来了极大便利，但在物理热工耦合、燃耗计算时需要对重复结构进行识别和展开处理。本文首先研究了对重复结构的识别方法；其次，研究了重复几何栅元展开为最底层的无重复几何独立栅元方法，并实现了相应的程序功能；最后，通过计算小型堆、大亚湾组件以及研究堆等一系列基准题和算例，比较了重复结构展开前后的反应堆有效增殖因子k_eff以及几何模型。结果表明：算例的计算结果的误差在36~187 pcm之间，重复结构展开前后计算结果吻合良好，几何模型结果也吻合良好，因此，证明了本文提出的重复结构展开方法具有较高的准确性和可靠性。

Abstract: The repeated structures bring great convenience to the geometrical modeling of nuclear reactor Monte Carlo program. However, in the physical thermal coupling and burnup calculation, it is necessary to identify and unfold repeated structures. Firstly, this paper studies the method of identifying repeated structures. Secondly, the method of unfolding repetitive geometric cells to the lowest level independent geometric cell without repetition is studied, and the corresponding program functions are realized. Finally, by calculating a series of benchmark problems and examples such as small reactors, Daya Bay components, and research reactors, the effective proliferation factor k_eff and the geometric model of the reactor before and after the unfolding of repeated structures were compared. The results show that the error of the calculation results of the example is between 36~187 pcm, the calculated results before and after the unfolding of repeated structures are in good agreement, and the results of the geometric model also agree well. Therefore, it is proved that the unfolding method of repeated structures proposed in this paper has high accuracy and reliability.