Halogenation of used aluminum matrix test reactor fuel - a bench-scale demonstration with surrogate materials

Experiments with surrogate materials were performed at bench scale to demonstrate a halogenation technique applicable to treatment of used aluminum matrix test reactor fuel. The technique involves dissolution and separation of aluminum from used aluminum matrix test reactor fuel in molten-halide salt systems prior to treatment and disposition of the fuel's uranium and fission products. Demonstration of the halogenation technique was performed with neodymium metal as a non-radiological surrogate for uranium metal. Experiments involved blending forms of aluminum and neodymium metal with ammonium and lithium chloride or ammonium and lithium bromide, which upon heating decomposed into ammonia gas and the respective hydrogen chloride or bromide gas. The latter reacted with the metals to form the respective aluminum and neodymium halides. At elevated temperatures, aluminum halides gasified away from the respective neodymium halides, which fused with their respective lithium halides. Samples of fused and distillate salts were collected and analyzed, yielding extents of aluminum removal that ranged from 94.5-98.2% for chlorination runs and 91.4-97.8% for bromination runs. No neodymium was detected in the distillate fractions. Some experiments were repeated with excess reactants, and a portion of aluminum chloride distillate was processed into a consolidated waste form.

Automated summary

Experiments were conducted to demonstrate a halogenation technique for treating used aluminum matrix test reactor fuel, involving dissolution and separation of aluminum in molten-halide salt systems before handling the fuel's uranium and fission products. The technique showed successful aluminum removal rates ranging from 94.5-98.2% for chlorination runs and 91.4-97.8% for bromination runs, with no detection of neodymium in the distillate fractions.