The behavior of fission products was consistent with the earlier results. Fission product removals were over 99 per cent for krypton, xenon, iodine, cesium, barium, and strontium, over 95 percent for yttrium, rare earths, and tellurium, and zero for the noble metals.

Uranium is a ductile metal and cannot be comminuted to a fine powder by any mechanical means such as crushing, milling or grinding. Uranium, however, reacts readily with hydrogen and forms UH3, which is a fine powder of less than 400 mesh screen size. The factors controlling the rats of the hydride formation are: (a) The surface area of the metal; (b) the temperature at which the reaction takes place; (c) the pressure of hydrogen. In order to increase the reaction area, one has to hydride small metal pieces rather than a single mass. The hydrogen reacts with uranium metal at temperatures as low as 100 deg to 1500 deg, and the reaction rate becomes quite rapid at approximately 225 deg C. The hydrogen for this purpose has to be of high purity and any small amount of oxygen in hydrogen delays the start of the reaction.

'Feed materials' refers to U metal, fabricated into fuel elements but not clad, and UF6, both normal isotopic content, suitable for introduction into Pu-production reactors or gaseous diffusion cascades.

Unclassified reports on processing of enriched UF6 into U metal, U-base alloys, UO2, and UO2SO4 for use a reactor fuels are annotated. Recovery of enriched U scrap, methods of isotopic analysis, health physics, criticality problems, and materials management are emphasized. A few references to papers presented at the Geneva Conference, 1955, and other recent nonreport literature are included. 254 references.