This annual report (1958) from the Hanford Atomic Products Operation. Various programs are briefly described including irradiation processing, fuels preparation, chemical processing, research and development, and supporting operations.

A series of critical experiments with blocks of 2% U/sup 235/--enriched UF/sub 4/-C/sub 25/sub 5/H/sub 52/ was initiated at the ORN L Critical Experiments Facility. Thus far assemblies with H:U/sup 235/ atomic ratios of 195 and 294 were built in parallelepipedal and simulated cylindrical geometries, both reflected and unreflected. From the results the minimum critical masses for reflected spheres were determined to be 16.3 and 8.5 kg of U/sup 235/ for fuel mixtures with H:U atomic ratios of 195 and 294, respectively. The minimum critical masses for unreflected spheres of these two fuel mixtures are 24.3 and 12.7 kg of U/sup 235/ respsctively. (auth)

A controlled-temperature irradiation capsule was operated containing small fueled specimens at 160O to 1650 F. The design involved calculating the specimen heat-generation rate and designing an insulating gas gap around the specimens to achieve the desired temperature. Electric heaters were inserted to help control temperature. The thickness and composition of the gas gap were modified prior to operation on the basis of information on probable neutron flux obtained from a nuclear mock-ups and on the basis of information on the thermal resistance of various gas annuli obtained from a thermal mock-up. The desired irradiation temperature of 1625 F was achieved with a variation of sintering time 25 F. (auth)