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Part 2. Chemistry


R. B. Brigs



coming few weeks. Small efforts continue on improvements to the reductive extraction process for rare earths and, more significantly, upon methods for removal of rareearth species from lithium chloride. Study of possible mechanisms of the intergranular attack upon the metallic components in MSRE now constitutes an appreciable fraction of the chemical research program. These studies, all initiated in recent months, have not yet produced information to report. The principal emphasis of analytical chemical development programs has been placed on methods for use in semiautomated operational control of molten-salt breeder reactors, for example, the development of in-line analytical methods for the analysis of MSR fuels, for reprocessing streams, and for gas streams. These methods include electrochemical and spectrophotometric means for determination of the concentration of U* and other ionic species in fuels and coolants, and adaptation of small on-line computers to electroanalytical methods. Parallel efforts have been devoted to the development of analytical methods related to assay and control of the concentration of water, oxides, and tritium in fluoroborate coolants.

The chemical development activities described below are, in the main, conducted to provide chemical information required in the development of molten-salt reactor systems. An appreciable, though diminishing, fraction of the effort is still devoted to postoperational examination of specimens and materials from MSRE. Such examinations, several of which are detailed in this document, should be largely concluded during the next reporting period. The behavior of hydrogen and tritium in molten salt, metals, and graphite constitutes a substantial fraction of the research and development effect. Solubility of hydrogen and its isotop& in molten fluorides is under study, as are rates of diffusion of hydrogen through pertinent metals and possible chemical exchange schemes capable of holding up the tritium to allow time for its controlled recovery. Studies of chemical separation of protactinium during this period have been confined to those based upon selective precipitation of oxides. It now appears that such a separation process is chemically feasible; we anticipate that, insofar as small-scale studies are concerned, these researches will be concluded during the