Molten salt reactors have gained substantial interest in the last years due to their flexibility and their potential for simplified closed fuel cycle operations for massive net-zero energy production. However, a zero-power reactor experiment will be an essential first step into the process delivering this technology. The choice of the optimal reflector material is one of the key issues for such experiments since, on the one hand, it offers huge cost savings potential due to reduced fuel demand; on the other hand, an improper choice of the reflector material can have negative effects on the quality of the experiments. The choice of the reflector material is, for the first time, introduced through a literature review and a discussion of potential roles of the reflector. The 2D study of different potential reflector materials has delivered a first down-selection with SS304 as the representative for stainless steel, lead, copper, graphite, and beryllium oxide. A deeper look identified, in addition, iron-based material with a high Si content. The following evaluation of the power distribution has shown the strong influence of the moderating reflectors, creating a massively disturbed power distribution with a peak at the core boundary. This effect has been confirmed through a deeper analysis of the 2D multi-group flux distribution, which led to the exclusion of the BeO and the graphite reflector. The most promising materials identified were SS304, lead, and copper. The final 3D Monte Carlo study demonstrated that all three materials have the potential to reduce the required amount of fuel by up to 60% compared with NaCl, which has been used in previous studies and is now taken as the reference. An initial cost analysis has identified the SS304 reflector as the most attractive solution. The results of the 2D multi-group deterministic study and the 3D multi-group Monte Carlo study have been confirmed through a continuous energy Monte Carlo reference calculation, showing only minor differences.

中文翻译：

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用于控制氯化物基熔盐零功率反应器的反射器选项的创新研究

熔盐反应堆由于其灵活性和简化闭式燃料循环操作以实现大规模净零能源生产的潜力，在过去几年中引起了极大的兴趣。然而，零功率反应堆实验将是实现这项技术过程中必不可少的第一步。最佳反射材料的选择是此类实验的关键问题之一，一方面，由于燃料需求减少，它提供了巨大的成本节约潜力；on the other hand, an improper choice of the reflector material can have negative effects on the quality of the experiments. 反射器材料的选择首次通过文献回顾和对反射器潜在作用的讨论进行介绍​​。对不同潜在反射器材料的 2D 研究提供了第一次向下选择，以 SS304 作为不锈钢、铅、铜、石墨和氧化铍的代表。此外，更深入的观察还发现了硅含量高的铁基材料。下面对功率分布的评估显示了慢化反射器的强烈影响，在核心边界处产生了一个峰值的大规模扰动的功率分布。通过对 2D 多组通量分布的更深入分析证实了这种效应，这导致排除了 BeO 和石墨反射器。确定的最有前途的材料是 SS304、铅和铜。最终的 3D 蒙特卡罗研究表明，与以前的研究中使用的 NaCl 相比，所有三种材料都有可能将所需的燃料量减少多达 60%，现在用作参考。初步成本分析已确定 SS304 反射器是最具吸引力的解决方案。2D 多组确定性研究和 3D 多组蒙特卡罗研究的结果已通过连续能量蒙特卡罗参考计算得到证实，仅显示出微小的差异。