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The importance of glass and glass-ceramic nuclear waste forms has been reaffirmed in recent years by the growing interest in nuclear power as a reliable energy source to meet the requirements of technologies such as artificial intelligence. Waste processing schemes for the disposal of halide-containing wastes will be essential for the advancement of nuclear technologies such as non-aqueous fuel reprocessing. Phosphate-based dechlorination and subsequent vitrification of radioactive salt waste into an iron phosphate waste form has been identified as a potential processing scheme for electrochemical processing waste. The impact of H3PO4-based dechlorination of complex salt mixtures on the vitrification processmore » and structure of the final iron phosphate waste form has not yet been investigated. In this work, iron phosphate glass-ceramics were made from simulant salt waste (48LiCl-33KCl-19NaCl mol%) dechlorinated with the H3PO4-based method. The glass forming region was compared to that of traditionally prepared Na2O-Fe2O3-P2O5 systems. For a candidate glass-forming composition, the processing scheme presented here was determined to favor Fe3+ species. The O/P molar ratio was consistent for the candidate composition when dechlorinated at 400°C and 600°C in air and argon environments, indicating glass network connectivity was maintained despite variations in processing parameters. The results presented here validate processing schemes requiring iron-phosphate waste form synthesis following H3PO4-based dechlorination.« less

Phosphate-based reagents are being considered by the U.S. Department of Energy (DOE) Office of Nuclear Energy to process halide salt-based nuclear wastes for stabilization prior to disposal. As evidenced by the Experimental Breeder Reactor-II (EBR-II) project, electrochemical processing (pyroprocessing) can be employed to recover uranium and other actinides for reintegration into the nuclear fuel cycle from metallic fuels. The resultant salt-based wastes generated from electrochemical processing of EBR-II fuel contains fission products within a LiCl–KCl eutectic salt that necessitate appropriate disposal. This paper provides an overview of recent efforts to support halide-based salt waste treatment for disposition, as well asmore » a basis for comparison with other related efforts in salt waste treatment through salt partitioning initiatives. The U.S. DOE has selected a phosphate waste form reference material for further investigation and longer-term studies.« less