FLiNaK熔盐中微量氧的测定

Determination of Trace Oxygen in FLiNaK Molten Salt

FLiNaK熔盐作为一种比较成熟的高温热载体,价格便宜、热稳定性好,可用作高温熔盐堆二回路冷却剂及太阳能传热蓄热介质.氧的存在对于熔盐堆安全运行存在多方面威胁,如降低核燃料的溶解度、氧化铀缓慢地发生沉淀进而造成燃料回路局部过热.然而,对于熔盐中氧含量的测定,目前还没有一个统一、通用的测定方法.基于氧分析仪（惰气熔融红外光谱法）在钢、铁、氧含量测定中的应用,建立了一个测定FLiNaK熔盐中氧含量的方法.针对FLiNaK熔盐的特性,选择了合适的包裹容器,确定了测定的裂解功率为2 800 W,方法测定熔盐中氧含量相对标准偏差为3.1％,加标回收率为85％～101％.

As a well-developed high-temperature heat carrier, FLiNaK molten salt is cheap and thermodynamically stable. It can be used as the second coolant in high-temperature molten salt reactor and solar heat transfer medium. The presence of oxygen greatly influenced the function of the molten salt reactor such as reducing the solubility of nuclear fuel, the precipitation of uranium oxide which would further lead to local overheating of the fuel circuit. However, there are still no general methods for the analysis of trace oxygen in the molten salt now. Based on the application of oxygen analyzer in the determination of trace oxygen in steel industry, we developed a practical method for the measurement of trace oxygen in FLiNaK molten salt. Optimal test conditions including suitable package container and the cracking power 2 800 W were established. The relative standard deviations of oxygen were 3.1% and the recoveries were 85 % ~101%.