Preparation of Curium—Americium Oxide Microspheres by Resin-Bead Loading

Abstract

A resin-bead loading and calcination technique developed at the Transuranium Processing Plant (TRU) of the Oak Ridge National Laboratory (ORNL) is used routinely for producing uniform particles of curium-americium oxide in the size range desired for the fabrication of targets for irradiation in the High Flux Isotope Reactor (HFIR). TRU is the storage, production, and distribution center for the heavy-element research program of the U. S. Department of Energy. Target rods are remotely fabricated at TRU, irradiated in the HFIR, and then processed chemically at TRU for the separation and purification of the heavy actinide elements. Berkelium, californium, einsteinium, and fermium are distributed to researchers. Unburned curium and americium that is recovered during the chemical processing is refabricated into targets for additional irradiation. About 200 g of curium-americium oxide is produced annually for use in fabricating HFIR targets. 50Start First Page Here. 35technique allows this criterion to be met easily even though remote operation is necessary for curium oxide production.In the following sections, a brief chronology of the development of this process is presented; the materials, equipment, and basic operations relating to the resin-bead loading and calcination method of producing sized curium-americium oxide microspheres at TRU are described; and typical production data are presented. Process DevelopmentDo Not Type Below This Line.During the mid-1960's, the feed material for the HFIR targets was 242p u . Plutonium oxide was prepared in glove box operations using hydroxide precipitation, calcination, andgrinding {]_)» When curium became available for use in HFIR targets, a sol-gel method for preparing curium oxide remotely was developed and was used from 1968 through 1970 (8).However, the sol-gel process was not well-suited for the small batch sizes that are involved in the TRU program. F.quipnient startup and shutdown were a major part of the operating time.The processing was plagued with erratic operation, poor yields, and production of oversize oxide particles that required undesirable grinding and screening operations. A simpler, more reliable oxide preparation method that was adaptable to remote operation was needed.The resin-bead loading and calcination process was deve- hich 150 g of curium oxide was successfully prepared and subequently used in HFIR targets. Two resins, which required lifferent process steps, were tested. The process using Dowex 0W resin, which contains sulfonic acid exchange groups, was elected for continued curium oxide production over a similar irocess using Amberlite IRC-50 resin, which contains carboxylic acid exchange groups. The Dowex 50W process (Fig. 1) requires ewer steps and is better suited for remote operation. In the )owex SOW process, pre-sized Dowex 50W-X8 resin beads are oaded to saturation from a dilute nitric acid solution of rurium-americium. The resin is rinsed with water and then the esin matrix is destroyed by calcination to form dense actinide 3xide micro...

Decomposition Analysis of Neodymium Loaded Resin

“…The decomposition process and the results of this research were anticipated from documentation [1,4,7] and from the DGA/TGA results shown in Fig. 14.…”

“…Drying helped provide more uniform gas flow and kept the resin from lifting out of the tube during subsequent steps. With the assistance of purge gases, the majority of the decomposition took place in the calcination step, which consisted of a burning segment where the hydrocarbon chain decomposes, a sulfur removal segment that was assisted by a change in purge gas, and then an oxidation period [1,7]. These transitions are not precise and depend upon the heating conditions.…”

“…The actinide oxide production process was developed as a simple and efficient procedure for manufacturing curium-americium (CmAm) oxide in a hot cell and was achieved by using a resin-bead loading and calcination process [1]. Cation exchange resins are used as a viable way to form spherical oxide microspheres suitable for use in the fabrication of transmutation targets irradiated in nuclear reactors.…”

“…This Cm oxide target material is blended with aluminum powder, formed into cermet pellets, and then encapsulated in an aluminum target rod for subsequent irradiation in the High Flux Isotope Reactor (HFIR). After irradiation, the pellets are dissolved and processed chemically to separate and recover heavy actinide elements such as berkelium, californium, einsteinium, and fermium for distribution [1]. In order to optimize production and recovery of the transcurium elements, it is necessary to have as much Cm in the original pellets as allowable.…”

“…The chemical "purity" of the actinide oxide is calculated from radiochemical analysis; calorimetric measurement of decay heat; and the assumed oxide stoichiometries CmO 1.71 , AmO 2 , and PuO 2 . The volume of actinide oxide allowed in a pellet includes impurities, which are typically on the order of 10 wt % of the oxide material [1]. These impurities are conservatively assumed to be equal parts elemental carbon and sulfur.…”