Selective separation of99Mo from fission products in chloride media on activated alumina

The radioisotope⁹⁹Mo generated through the fission of neutron-irradiated uranium targets was separated in an extremely radiochemically pure state. The target dissolution mixture was run on a silica gel column whereby the⁹⁵Zr−⁹⁵Nb activity, the serious radiocontaminants of⁹⁹Mo, was adsorbed on the gel. The effluent from the gel column was processed and treated with sodium dihydrogen phosphate. The processed solution was run on an activated alumina column whereby⁹⁹Mo was adsorbed as phospho-molybdate complex ion, then desorbed from the column as the molybdate ion by eluting with 10% NaOH solution. By recycling the adsorption and desorption steps on alumnia,⁹⁹Mo was finally obtained totally free from all other radiocontaminants.     

Preparation of99Mo,132Te isotopes and99mTc,132I generators

Adsorption and desorption of⁹⁵Zr−⁹⁵Nb,⁹⁹Mo,¹⁰³Ru,¹³²Te and²³⁹Np in a HCl-alumina system were studied in order to purify⁹⁹Mo and¹³²Te obtained by the cation-exchange separation of fission products and to prepare highly pure^99mTc and¹³²I generators.⁹⁹Mo and¹³²Te, of which radionuclidic purity was over 99.99% and 99.999%, respectively, could be obtained by passing the cation-exchange separated Mo and Te fractions through alumina columns, by washing with HCl and finally by eluting⁹⁹Mo with 1M NH₄OH and¹³²Te with 3M NaOH. In order to raise the recovery of⁹⁹Mo and¹³²Te from the alumina columns, they should be eluted as quickly as possible after the adsorption. The direct use of the alumina column containing⁹⁹Mo or¹³²Te as the generator allowed milking of^99mTc or¹³²I, of which radionuclidic purity was over 99.999%. Milking yields of^99mTc with 0.1M HCl and¹³²I with 0.01M NH₄OH were 77% and 90%, respectively. The latter value was much higher than that in usual performance of the generator.     

Separation of trace impurities of131I from99Mo obtained by extraction from fission products of uranium

The radioisotope⁹⁹Mo was separated from a mixture of²³⁵U fission products in the presence of Hg²⁺ by sorption on a chromatographic column filled with Al₂O₃ and elution with 1M NH₄OH. Trace impurities of¹³¹I in the molybdenum fraction were eliminated by selective sorption on silver iodide or by repeated sorption of⁹⁹Mo on Al₂O₃.     

Speciation and adsorption of trace-level fission product of 132Te, 95Zr, 99Mo and 103Ru on inorganic materials

The potential uses of hydrous oxides in the treatment of radioactive wastes may be affected by the physical-chemical properties of these materials. The sorption behavior of trace level (less than 10^-14 g/ml) ²³⁵U fission products in aqueous solutions was studied under static conditions on TiO₂, MnO₂ and SnO sorbents. A variety of anions, cations and neutral species of ¹³²Te,⁹⁵Zr, ⁹⁹Mo and ¹⁰³Ru in aqueous solutions at 1, 3, 5, 7 and 10 pH values were identified and their retention values were calculated. High voltage electrophoresis was used to establish the chemical species of these radioisotopes formed in the solution. This revised version was published online in July 2006 with corrections to the Cover Date.     

Separation of 99Mo from a simulated fission product solution by precipitation with a-benzoinoxime

The formation property of Mo precipitate was investigated and improved the existing process was using H₂O₂ that acts as an interfering compound in a subsequent alumina adsorption process. The property of the Mo precipitate was investigated by using SEM, FTIR, TG-DTA, and XRD. The simulated solution consisted of 1M nitric acid containing seven elements (Mo, I, Ru, Zr, Ce, Nd, Sr) and their radioactive tracers. As a result, the precipitate was composed of the Mo precipitate and re-precipitated a-benzoinoxime which was added excessively for increasing the precipitation efficiency. It was confirmed that the Mo precipitate was formed by the reaction of two a-benzoinoxime molecules and one MoO₂ ²⁺. Molybdenum precipitate was dissolved in 0.4M NaOH solution within 5 minutes without H₂O₂. Hydrogen peroxide induced only the rapid dissolution of the a-benzoinoxime re-precipitate. Also, the dissolution method without H₂O₂ was favorable in the purification aspect because Zr and Ru were contained as a small fraction of 1.3% and 7.7%, respectively, in the dissolving solution.     

Separation of yttrium from heavy lanthanide by CA-100 using the complexing agent

The selective extraction of yttrium from heavy lanthanide by liquid-liquid extraction using CA-100 in the presence of the complexing agent, such as EDTA, DTPA, and HEDTA was investigated. The extraction of heavy lanthanide in the present of the complexing agent was suppressed when compared to that of Y because of the masking effect, but the selective extraction of Y was enhanced. All complexing agents formed 1:1 complex with rare earth elements (RE), and only free rare earth ions could take part in the extraction. The condition for separation was obtained by exploring the effects of the complexing agent concentration, the extractant concentration, pH and the equilibration time on the extraction of the heavy rare earth elements.     

Extraction-chromatographic separation of uranium from long-lived fission products using tributyl phosphate

Extraction-chromatographic separation of uranium from fission products was performed using undiluted tributyl phosphate sorbed on Chromosorb W as a stationary phase, and nitric acid (1: 3) as a mobile phase. Most of the fission products that contributed greatly to the radiation level of the sample passed through the column; this effected considerable decontamination. Uranium retained on the column was quantitatively recovered by elution with water.     

Separation of iodine produced from fission with a porous metal silver column in99Mo production

In Argentina, at the Ezeiza Atomic Center,¹³¹I is produced by wet distillation of natural tellurium dioxide irradiated with thermal neutrons in a pool-type reactor. In order to recover the¹³¹I present in the production process of fission⁹⁹Mo obtained by irradiation of UAL_x/Al targets (with 90% enriched uranium) a separation method was developed. Iodine isotopes can be separated from a sodium hydroxide solution containing fission products using a column filled with alternate beds of glass microspheres and porous metal silver. Tests with tracers were performed in radiochemical laboratory. Following this results, a series of tests with higher activities (3 TBq of⁹⁹Mo and 0.7 TBq of¹³¹I) were carried out in hot cells. Molybdenum passes through the silver column, while¹³¹I retention was 92–97% in tracer test and 90% in optimised hot cell tests. This result depends on several facts that are discussed. An initial separation of iodine isotopes diminishes radiation damage on ion-exchange resin used in the subsequent molybdenum purification, improving its retention and elution yield.     

The separation of99Tc from mixed fission products and its determination by neutron activation

Technetium is separated from the bulk of fission products and other elements in dissolved nuclear fuel by a ferric hydroxide precipitation followed by filtration and loading of the filtrate on an anion exchange resin. The technetium remains on the resin presumably as pertechnate ion. The resin is exposed to a neutron flux in a nuclear reactor activating⁹⁹Tc to¹⁰⁰Tc which decays with the emission of a 539keV gamma-ray with a 15.8 second half-life. This gamma-ray is conveniently counted with conventional solid state techniques.Work performed under contract to the U. S. Department of Energy under contract number DE-ACO7-76IDO1570.     

A novel technique for the separation of99mTc from99Mo

A new technique for the separation of^99mTc from low specific activity⁹⁹Mo is reported. A separation based on the principle of precipitation of⁹⁹Mo as calcium molybdate has been investigated. On precipitating⁹⁹MoO ₄ ^2– from alkaline solution as calcium molybdate under controlled conditions, the^99mTcO ₄ ^– is found to remain quantitatively in the supernatant solution with little carry-over of⁹⁹Mo. This calcium molybdate (⁹⁹Mo) could be redissolved and reprecipitated at regular intervals, yielding^99mTc quantitatively in aqueous neutral solutions. Calcium molybdate precipitates containing up to 1.5 GBq of⁹⁹Mo and 130–180 mg of molybdenum were prepared and evaluated. The performance in terms of repeated^99mTc separation gave yields of 75–93% with acceptable readionuclidic and radiochemical purity.     

Quantitative separation of carrier-free cerium from fission products

The extraction of Ce (IV) by di-(2-ethylhexyl)-phosphoric acid (HDEHP) has been studied as a function of nitric acid concentration. Using the distribution coefficient data, the optimum conditions for recovery of Ce (IV) from nitric acid medium were arrived at. Under the conditions employed for Ce(IV), a small percentage of Ru was also found to be extracted. Cerium could be selectively stripped from the organic phase with 8M HNO₃/30% H₂O₂ solution. This procedure led to the recovery of¹⁴⁴Ce free of¹⁰⁶Ru. Based on the solvent extraction data, an extraction-chromatographic procedure employing HDEHP (40% w/w) loaded on Amberlite XAD-7 as the stationary phase was developed for the isolation of pure, carrier-free¹⁴⁴Ce from the spent fuel solution.     

Separation of carrier-free115mIn from115Cd and132I from132Te over the zirconium oxide column

A new way of radiochemical separation of carrier-free^115mIn from¹¹⁵Cd and¹³²I from¹³²Te over the column of zirconium oxide is described. Activities of Cd and In in equilibrium in dilute acetic acid solution were bufferred with dilute sodium acetate and fed into the column at a pH 7, when cadmium activity passed out unadsorbed and the^115mIn was adsorbed in the column. A study of the γ-ray peak of the separated^115mIn showed that the product is of high radionuclidic purity. Te-I pair was separated by passing the weakly acidic solution of¹³²Te and¹³²I in the presence of AgNO₃ and Na₂SO₃, through the column where both activities were adsorbed. Iodine was washed outh with 5% sodium thiosulphate solution and the retained tellurium activity was later washed out with 6M HNO₃. The β-decay study showed that the separated¹³²I product is of high radiochemical purity. The processes took less than half an hour and the yields were quantitative.     

Separation of curium from americium using composite sorbents and complexing agent solutions: part 2

TODGA–PAN composite sorbent and (PhSO₃H)₂–BTPhen in nitric acid solution were employed as a system for separation of curium from americium. The influence of aqueous phase composition (complexing agent and nitric acid concentrations) on weight distribution coefficients and Cm/Am separation factor was studied in batch experiments with trace amounts of ²⁴¹Am and ²⁴⁴Cm. Based on the results obtained, column experiment was designed and conducted. The Cm/Am separation factor of 3.8 ± 0.1 found in batch experiments with TODGA–PAN could be reproduced also in column experiment resulting in good separation of Cm from Am. The efficiency of Cm separation from Am in the TODGA–PAN system was compared with the analogous system with DGA resin (Triskem International). After separation on a 0.5 mL column (φ4.7 × 29 mm) the Cm fraction containing 93% of Cm(III) contained only 3% of Am(III) in optimum conditions.

     

Application of cellulose anion-exchangers to separation of palladium from platinum or iridium with glycine as complexing agent and atomic-absorption spectrometry for detection

The use of glycine as complexing agent for chromatographie separation of palladium from platinum, or palladium from iridium, on cellulose anion-exchangers has been investigated and found possible over a wide range of concentration ratios. The method can be used for analysis of Pd-Ir alloys. The nature of the complexes taking part in the ion-exchange has been identified.     

Solvent extraction studies using tetracycline as a complexing agent. XIII. Application of tetracycline for separation of interfering elements in activation analysis of uranium

Tetracycline in solution of benzyl alcohol was used as an extracting agent to separate uranium from interfering elements in the determination of uranium and of isotopic ratio²³⁵U/²³⁸U by neutron activation analysis. Separation gives a recovery of 97% for uranium and the interferences from matrices of pitchblende and monazite are eliminated.From a dissertation submitted by R. Petrauskas to the University of São Paulo in partial fulfilment for a Master of Science Degree in Nuclear Technology.