In the context of the demonstration of the UREX (uranium extraction) process, a separation of uranium and technetium using an anion exchange resin was performed on a simulant solution containing 98.95 g/L of {sup 238}U and 130.2 mg/L of {sup 99}Tc. After sorption on the resin, TcO{sub 4}{sup -} was eluted with NH{sub 4}OH, the eluting stream was treated, and the technetium converted to Tc metal (yield = 52.5%). The purity of the compound was analyzed: it contains less than 23.8 {micro}g of {sup 238}U per gram of {sup 99}Tc. Tc metal was characterized by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) spectroscopy; EXAFS analysis clearly confirms the hexagonal structure of the metal obtained after treatment. Uranium was converted to ammonium diuranate and to U{sub 3}O{sub 8} in a yield of 88.2%, analysis indicates that the compound contains less than 0.16 {micro}g of {sup 99}Tc per gram of ammonium diuaranate.

http://radchem.nevada.edu/docs/pub/U%20Tc%20separation%20UREX%20%28solid%20forms%29.pdf

Uranium/technetium separation for the UREX process - synthesis and characterization of solid reprocessing forms

This paper provides a useful and quick reference source to the 1999 journal literature on adsorptive and membrane-type separations (from the 50 most important chemical engineering journals) for researchers in this area. This article continues a series of annual bibliographic updates of the literature published since 1985 (see Ray 1990-1999). The references included here have been divided into the following subject groups: theory; design data; adsorbents; PSA and cyclic systems, and applications; liquid-phase adsorption; ion exchange, chromatography and related separations; membranes; and membrane-type separations. Adsorption and related separations for industrial and environmental applications are described in detail by Dabrowski (1999) which also contains extensive bibliographies prepared by this author. A complete bibliographic listing of the chemical engineering journal literature from 1959 to 1999 (with subsequent six-monthly updates) is available on a CD-ROM database and full details can be obtained ...

https://journals.sagepub.com/doi/pdf/10.1177/026361749901700307

Adsorptive and Membrane-type Separations: A Bibliographical Update (1999)

The radiolysis of poly(4-vinylpyridine) quaternary salt ion exchange resins

Metallic fuel is reprocessed by a compact nonaqueous pyrochemical process. The present study explores the possible uses of an aqueous reprocessing-based method as an alternative to the pyro-processing of metallic fuels. Solvent extraction studies in the batch mode were carried out for both U–Zr- and U–Pu–Zr-based metal alloy systems. Earlier studies carried out in our laboratory have established that Tri-iso-amyl Phosphate (TiAP) is a promising extractant for the reprocessing of spent fuels. In the present study, the distribution data has been generated for the extraction of uranium and zirconium as a function of equilibrium aqueous phase metal ion and nitric acid concentration with TiAP and Tri-n-butyl Phosphate (TBP)-based solvents. These studies indicate the formation of a third phase with zirconium in the presence of uranium with TBP under certain experimental conditions whereas it was not encountered with the TiAP system. Flow sheet for the co-extraction and co-stripping of heavy metal ions b...

Studies Related to the Processing of U–Zr and U–Pu–Zr Metallic Fuels Using Tri-iso-amyl Phosphate (TiAP) as Extractant

Despite reports of the relative inertness of ReillexTM HPQ to chemical and radiolytic degradation, thermal stability studies in nitric acid solutions identified a low temperature exothermic reaction using the Reactive System Screening Tool (RSST). Comparative data for ReillexTM HPQ and IonacTM A-641 both show runaway behavior in nitric acid above 130˚C, but only ReillexTM HPQ had a low temperature exotherm that initiated at about 69˚C. While this exotherm is small in magnitude, gaseous products were identified, leading to concerns of pressurization within the ion exchange column. This work identifies and characterizes the low temperature exothermic reaction of ReillexTM HPQ in nitric acid, identifies ethylbenzene pendant groups as the origin of this reaction, and proposes a chemical pretreatment to eliminate it.

Low temperature exothermic reaction of reillextm hpq in nitric acid

Reactive System Screening Tool(TM) data and a computational model are used to predict the impact of pressurization on a typical process-scale ion exchange column due to gases generated by a low temperature exothermic reaction (LTE). The LTE results from a reaction between nitric acid and the ethylbenzene pendant groups of the Reillex(TM) HPQ resin. This reaction would occur if the resin bed were inadvertently heated above 70 degrees C.

/pdf/impact-of-the-low-temperature-reactivity-of-reillex-hpq-on-1s19j3cp94.pdf

Impact of the low-temperature reactivity of reillex™ hpq on actinide processing

/pdf/qualification-of-reillexf-hpq-anion-exchange-resin-for-use-3r174g3kzf.pdf

Qualification of Reillexf HPQ Anion Exchange Resin for Use in SRS Processes

An adsorption process utilizing activated alumina and activated bauxite adsorbents was evaluated as a function of operating parameters for the removal of low level radioactive contaminants from organic waste solvent generated in the fuel reprocessing facilities and support operations at Savannah River Site. The waste solvent, 30 vol% tributyl phosphate in n-paraffin diluent, was degraded due to hydrolysis and radiolysis reaction of tributyl phosphate and n-paraffin diluent, producing fission product binding degradation impurities. The process, which has the potential for removing these activity-binding degradation impurities from the solvent, was operated downflow through glass columns packed with activated alumina and activated bauxite adsorbents. Experimental breakthrough curves were obtained under various operating temperatures and flow rates. The results show that the adsorption capacities of activated alumina and activated bauxite were in the order of 10{sup 4} and 10{sup 5} dpm/g of adsorbent, respectively. The performance of the adsorption process was evaluated in terms of dynamic parameters (i.e., adsorption capacity, the height and the efficiency of adsorption zone) in such a way as to maximize the adsorption capacity and to minimize the height of the mass transfer or adsorption zone.

/pdf/adsorption-decontamination-of-radioactive-waste-solvent-by-ip1p433zix.pdf

Adsorption Decontamination of Radioactive Waste Solvent by Activated Alumina and Bauxites

The processing of residues left over from the passing of the Cold War presents new challenges. Solvent extraction processing of high-fluoride-content plutonium residues requires some adjustments in order to prevent high losses of plutonium to the waste stream. Process solutions have a fluoride:plutonium ratio of up to 300:1 and contain up to 0.35 M total fluoride in nitric acid solution. Either complexing the fluoride with aluminum or increasing the total nitrate in the feed stream will increase the plutonium extraction into tributyl phosphate (TBP). The favored option was to perform minimal dilution of the dissolver solution to keep the concentrations of nitrate and plutonium high and to add sufficient aluminum nitrate to give acceptable plutonium extraction. This approach minimizes additional waste generation from aluminum salts. Determination of acceptable process chemistry conditions required a better understanding of the competition between fluoride and nitrate for the complexation of plutonium in a ...

Edward A. Kyser

Papers

Low temperature exothermic reaction of reillextm hpq in nitric acid

Impact of the low-temperature reactivity of reillex™ hpq on actinide processing

Qualification of Reillexf HPQ Anion Exchange Resin for Use in SRS Processes

Adsorption Decontamination of Radioactive Waste Solvent by Activated Alumina and Bauxites

Extraction of plutonium into 30% tributyl phosphate from nitric acid solutions containing fluoride, aluminum, and boron