The average energy release per fission event in a reactor is dependent on the composition and arrangement of the lattice materials. In a study of heat generation in the NPR, Nilson developed expressions for calculating the average energy released in each material per fission event. These relationships have been used in the present calculations to obtain the energy release per fission in existing Hanford reactors.

A process was developed for separating promethium from raixed fisBion product rare earths by continuous multistage conntercurrent extraction with 100% tri-nbutylphosphste from nitric acid of 12 N or higher concentration. Distribution coefficients at 12 N acidity for aecdamium. promethium. and samarium are 0.43. 0.82, and 1.55, respectively. Single-stage separation factors of 1.9 between successive elements can be maintained throughout the system to give separations dependent only on the number of stages. Extracted values can be recovered from the organic solution by stripping with a smaller volume of dilute nitric acid. A flowsheet for purification of promethium includes one cycle for separation of promethium from neodymum and lighter elements and a secondycle for removal of samarium and heavier elements. Each cycle consists of a series of countercurrent partitioning stages. followed by stripping stages and an evaporator. With 20 stages in the first cycle and 34 stages in the second, a 90% yield of promethium with a purity of 83% can be obtained from a typical mixture of fission product rare earths, assuming essentially perfect mechanical efficiency. An increase to 34 stages in the first cycle would permit a 93% yield of 99% promethium. (auth)

The conditions under which hydrogen could be quantitatively recovered from mixtures of gases by oxidation over fixed beds of CuO were investigated. The conversion of H/sub 2/ to H/sub 2/O by reduction of CuO in fixed beds increased with in- creasing bed length, temperature, hydrogen/argon ratio, and decreasing mesh size of CuO. Residence times required for 99% conversion in a 1- in.-diam. bed were 0.6 and 1.2 sec for 30% hydrogen-70% argon and 10% hydrogen90% argon mixtures, respectively, at a total gas flow of 1 l/min. The CuO used was 25-mil-diam. wires with a surface area of 0.019 m/sup 2//g. The residence time required for a given value of conversion decreased about 10% when the total flow rate was increased from 1 to 1.7 liters/min, which indicates that the reduction is mass-transfer controlled to a slight extent under the experimental conditions used. (auth)