Effect of Uranium Recycle on Transuranic Element Buildup

Abstract

The buildup of the important transmutation products in irradiated uranium was calculated. Significant quantities of such products are produced upon irradiation with pile neutrons. These quantities are further increased with subsequent recycle through power reactors. The nuclides are U/sup 236/, U/sup 237/, Np/sup 237/, and Pu/sup 238/. Varibles included were; irradiation levels of 6 x 10/sup 19/ to 3 x 10/sup 21/ n/cm/sup 2/; effect of recycle in the range 1 to 400 cycles and infinite recycle; initial fuel enrichment in the range of 0.5 to 3.0% U/sup 235/; and the effect of fraction of U/sup 236/ removed by a gaseous diffusion plant reconcentration of U/sup 235/ in the range 0 to 100% removal. This last variable depends on the operational characteristics of the diffusion plant. The buildup of transmutation products may have many appreciable effects on the design and operation of fuel recycle. The decay time required will increase as a result of higher concentrations of U/sup 237/; chemical separation plants may be required to separate Np/sup 237/ as well as uranium. plutonium, and fission products; and the buildup of Pu/sup 238/ in the plutonium more » product may create additional biological or handling problems. An impontant conclusion of this work is that all problems resulting from isotope buildup in the U/sup 235/ buildup chain may be decreased in seriousness by approximately an order of magnitude with removal of about 25% of the U/sup 236/ by re-enrichment in a gaseous diffusion plant. (auth) « less