The 235,238 UF 4 was irradiated by photo-neutrons, distribution and behavior of the fission product 95 Nb from irradiated 235,238 UF 4 in FLiBe salt were investigated by the measurement of its activity in the salt with the γ-ray spectroscopy. The experiments indicated that a part of 95 Nb deposited on the surfaces of graphite and Hastelloy, as the moderator and the structural materials of molten salt reactor (MSR), respectively, and the majority of 95 Nb maintained in molten salt. Addition of lithium metal made 95 Nb in salt to be reduced and settled, leading to the decrease in its activity. Degree of the decrease was found to be correlated with niobium concentration. The experimental results supported the statement proposed early by ORNL, that 95 Nb might be used as a redox indicator for MSR. Finally, the problem met with on-site monitoring for redox potential in MSR was pointed, and a possible protocol to resolve the problem was proposed.

中文翻译：

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裂变产物95Nb在FLiBe盐中的分布和行为

用光中子辐照235,238 UF 4，通过γ射线光谱法测量其在FLiBe盐中的活性，研究了辐照的235238 UF 4在FLiBe盐中的裂变产物95 Nb的分布和行为。实验表明，一部分95 Nb分别沉积在石墨和Hastelloy的表面上，作为熔融盐反应器（MSR）的慢化剂和结构材料，而大部分95 Nb保留在熔融盐中。添加锂金属使盐中的95 Nb减少并沉淀，导致其活性降低。发现降低的程度与铌浓度相关。实验结果支持ORNL早期提出的陈述，即95 Nb可用作MSR的氧化还原指示剂。最后，