A new method for the radiochemical separation of copper from fission products

A new method for obtaining radiochemically pure⁶⁷Cu from highly active fission product solutions is described. The method is based on the solvent extraction of the Cu(II)-diethyldithiocarbamate complex in n-butyl acetate in the presence of hold-back carriers for Ni, Co, Mn, Mo, rare earths, Cd, Te and Sb, and subsequent purification steps involving scavengings for Ag, Ba, Sr and Fe followed by an anion-exchange purification step for decontamination from Te. Copper is finally extracted as the α-benzoin oxime complex in which form it is mounted and counted. The method has several advantages over other methods in that decontamination is very high and it is sufficiently fast considering the stringent radiochemical purity achieved. The⁶⁷Cu separated by this procedure from a one-day-old mixture of fission products arising from 10¹⁰ fissions was found to be completely free of any contamination.     

A rapid radiochemical procedure for indium

A rapid radiochcmical procedure was developed for the separation of indium radionuclides from a mixed fission-product solution. An alcoholic pyridine solution is added to a uranium solution containing indium and tin carriers. The resulting tin precipitate is separated from the indium-containing solution by filtering through a cellulose membrane filter. The decontamination factor for tin is 2·10³. Other fission products are only partially removed. The chemical yield of indium is about 44%, and the time required for the separation is about 10 sec. After the tin-separated indium has decayed, the tin daughters of indium are removed from all the other fission products at a specified time and measured, so that the amount of indium present at the time of the tin precipitation is determined.     

A rapid iodine radiochemical procedure

A radiochemical procedure was developed to determine fission yields and radiation characteristics of short-lived iodine fission products.Iodine was separated from other fission products of uranium in less than 10 sec after completion of irradiation. High decontamination factors of iodine from Sn, Sb, Te, Xe, Cs and Ba, and high chemical yields were obtained. The sample was prepared by dissolving uranium peroxide in molten periodic acid; the melt was cooled, ground and mixed with activated carbon. After irradiation, the periodic acid was decomposed by heat and the gaseous iodine formed was collected in carbon tetrachloride or in a cooled counting chamber. Higher temperatures could be used than in conventional aqueous systems, thus enhancing the exchange of carrier and fission product iodine.     

A rapid radiochemical method for antimony and arsenic : Development and testing of the method

The formation of stibine and arsine by flash electrolysis is applied to the rapid separation of radioactive isotopes of antimony and arsenic from a mixture of fission products. A chemical yield of 45% for both antimony and arsenic was achieved in 10 sec. The conditions necessary for the clean separation of antimony and arsenic from one another and from other fission products are described. The method proved successful both in the laboratory and in a nuclear reactor.     

Selective extraction and separation of cadmium using tri-n-octylamine

The extraction of cadmium by tri-n-octylamine in benzene and cyclohexane from a mixture of sulphuric acid and potassium bromide has been investigated in detail. The optimum conditions for the extraction and back-extraction of cadmium have been found. The procedure for the concentration of cadmium is described and the separation of cadmium in the presence of more than 30 metals including fission products is presented.     

Comparison of quantitative and substoichiometric determination of caesium from fission products with nitrobenzene solution of lithium dipicrylaminate

A method of determination of ¹³⁷Cs in a fission product by extraction with a nitrobenzene solution of lithium dipicrylaminate is described. The effect of pH and the amount of reagent on the efficiency of extraction of micro-amounts of caesium has been studied as well as the competing effect of alkali metal salts; the possibility of substoichiometric determination of caesium has been also investigated. Both procedures have been tested with an artificial mixture of fission products.     

Separation of uranium from complex nuclear reaction product mixtures

A solvent extraction procedure for rapid separation of uranium from complex nuclear reaction product mixtures is suggested. The procedure has been tested in batch experiments with tracer amounts of representative elements. It has also been tested with fission products and uranium tracer using the continuous chemical separation system SISAK at the Mainz TRIGA reactor.     

Determination of plutonium by isotopic dilution mass spectrometry following TTA-extraction

Isotopic dilution mass spectrometry has been applied to assess the plutonium concentration in samples such as those obtained from the dissolution of irradiated uranium fuels in a reprocessing plant. Prior to the analysis, plutonium is taken through a redox cycle and is separated from uranium and fission products by extraction into TTA-xylene. The extraction procedure, the standardization of the spike solution and the mass assay of the plutonium are described; typical results under plant conditions are given. The overall precision of a single measurement of the plutonium concentration is 0.6%, expressed as relative standard deviation, including the plant sampling error, dilution error and analytical error.     

An improved radiochemical procedure for low-level measurements of americium in environmental matrices

The chemical yield and accuracy of measurements of (241)Am at low levels in marine environmental matrices have been substantially improved by applying the extraction procedure with DDCP (dibutyl-N,N-diethylcarbamylphosphonate). The improved procedure is described, and its advantages over the conventional procedure are discussed.     

Systematic radiochemical analysis of fission products

A scheme for the sequential separation of fission products has been developed on the basis of ion-exchange techniques. It consists of a main cation-exchange process for group separation and subsidiary processes of cation or anion exchange for further separations or purifications of the individual fission products. By the present method, Zn, Rb, Sr, Y, (Zr), Mo, Pd, Cd, Te, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu and Tb can be separated simultaneously from an irradiated uranium sample. Of these, alkali, alkaline earth and rare earth metal ions are separated quantitatively. A polarographic method was applied to determine the recoveries of Zn, Mo, Pd, Cd and Te, which were not separated quantitatively.     

Nuclear decay studies of rare-earth fission-product nuclides using fast radiochemical separation techniques

A facility for the rapid radiochemical separation of individual rare-earth fission product nuclides from mixed fission products has been developed at the Idaho National Engineering Laboratory (INEL). This facility, called the INEL ESOL (elemental separation on-line) facility, includes an electroplated spontaneously fissioning²⁵²Cf source, a He jet transport system to deliver short half-life fission products from the²⁵²Cf hot cell to the radiochemistry laboratory, and a high pressure liquid chromatograph for the individual separation of rare-earth radioelemental fractions. The fission product collection and separation instrumentation is interfaced to a microprocessor that controls valves, motors and other devices and monitoring instrumentation. The data acquistion instrumentation can be controlled from a signal originating from the microprocessor or initiated manually. The results of some recent decay scheme studies on¹⁵³Pm and¹⁵⁴Pm are reported.     

Determination of uranium,plutonium and selected fission products in the coolant of the KS-150 reactor

The method of monitoring of U, Pu and some fission products (^103,106Ru,^134,137Cs and^141,144Ce) in gaseous CO₂ coolant is described. The method is based on the retention of the radionuclides studied by membrane filters built in by-pass of the burst-cartridge detection (BCD) system. The purpose of the present study was the determination of U, Pu in CO₂ and the verification of the possibility of the indirect monitoring of U and Pu contents in the coolant, using the gamma-spectrometric determination of selected fission products retained by the filter. For calibration of the proposed method after decomposition of the filters, uranium was determined spectrophotometrically using Arsenazo III, plutonium was determined radiometrically after its separation by extraction with 2-thenoyltrifluoracetone and the fission products were determined by gamma-spectrometry. From the results obtained it follows that a correlation exists between the U and Pu content in the coolant and the activity of certain fission products retained on the filter.     

A rapid radiochemical method for antimony and arsenic : Part I. Formation of stibine and arsine by flash electrolysis

The formation of stibine and arsine affords a clean, one-step, method of separating antimony and arsenic from fission products. The development of a high-current electrolytic cell for the rapid formation of these hydrides from a hydrochloric acid electrolyte, is described. A chemical yield of 45% was achieved for both antimony and arsenic in 10 sec. The effects of pH and antimony and arsenic oxidation states were also studied. In 5 N hydrochloric acid, the chemical yield is independent of the antimony oxidation state. For arsenic however, the yield of arsine is 7 times greater for As(III) than for As(V).     

Use of radiochemical methods as tools for speciation purposes in environmental and biological sciences.

Chemical speciation for a few elements can be facilitated to a great extent by incorporating a suitable radioisotope into the system and measuring the radiation of the isolated species. This radiospiking can be applied to in vitro and in vivo labelled experiments. Radionuclides are, however, also present as an anthropogenic contaminant from various nuclear fission activities. The radiotracer should be added under such conditions that it behaves in exactly the same way as the isotopes it represents. It should possess an adequate radioactive half-life, and preferably be a gamma-emitter because of the ease of detection. Radiotracer labelling is now widely used to study speciation problems of many essential and toxic elements in body fluids and tissues. It can be used to trace the different locations where the element is metabolized and stored, and subsequently to detect the element in the isolated biocomponents. The determination of the location of a radiotracer in a cell by autoradiography proved to be impractical because of the lack of resolution. Radiochemistry is similarly very useful for investigating particular aspects of the speciation of heavy metals as they occur in the ecosystem, and to follow the fate and effects of fission nuclides in the environment as they are carried around by the water and air masses. However, in certain circumstances the behaviour of fission products appears to be different from that of their stable analogues. For the actinides they simply do not exist. Radiochemical methods are a major tool for identifying and quantifying the nuclides in the different species.     

Sequential substoichiometric radiochemical separation of selenium,thallium and cadmium

A procedure for sequential radiochemical separation of Se(IV), Tl(I) and Cd(II) has been developed. This procedure involves substoichiometric solvent extraction of these ions with 2-mercaptobenzothiazole (2-HMBT) under different experimental conditions.     

A rapid and selective separation of palladium

Palladium was separated from Al, Ru, Rh, U, Pu and also from a mixture of fission products using -benzoin-oxime as the extractant and Solvesso-100 as the diluent. The extraction is quantitative over a wide range of acidity from 0.1M to 4M HNO₃. The method has been found to be equally effective to separate Pd at trace level (carrier-free form). The stoichiometry of the complex, the interference of foreign elements in Pd separation, etc., are reported. The applicability of the method to separate palladium formed in fission rapidly from all other fission products, especially the most strongly interfering molybdenum isotopes, and the recovery of this element from high level radioactive waste are also mentioned.     

Rapid radiochemical separation of selenium

A rapid separation of selenium based on the extraction of Se(IV) from 4M hydrobromic acid into benzene containing 1 % of phenol, is described. Recoveries of 99 % are achieved in less than 5 min. Oxidizing and reducing agents interfere. The separation is highly selective for selenium.     

Determination of traces of uranium in tungsten and molybdenum by radiochemical neutron activation analysis via the fission product140Ba

A radiochemical separation procedure has been developed to determine traces of uranium in tungsten and molybdenum. In this procedure the fission product¹⁴⁰Ba, as indicator nuclide for uranium, is selectively separated from the matrix activities and from all other long-lived activation and fission products and obtained at high purity. The radionuclide in the final fraction is sufficiently pure so that it can be measured with high counting efficiency by -counting. The separation procedure consists of two steps: a cation-exchange separation to separate barium from the anionic matrix tungste or molybdate, and many other elements. In the second step the Ba-fraction is further purified by precipitation of barium as barium chloride in 8M hydrochloric acid. The precipitate is then dissolved in water for -counting via the Cerenkov effect. The chemical yield for barium is 94.6±2.6%. When samples of 0.1 g, a thermal neutron flux of 2·10¹³ n·cm^–2·s^–1, an irradiation time of 10 hours and a measuring time of 2 hours were applied, then the detection limit of uranium was 4 ng/g.Presented at the 3rd Intern. Conf. on Nuclear and Radiochemistry, Vienna, September 7–11, 1992.     

Rapid chemical separation procedures

Fast, discontinuous separation procedures are described for zirconium, niobium, technetium and antimony from fission products. Other rapid separation methods from aqueous solutions are summarized. The combination of a gas jet recoil transport system with a continuous solvent extraction technique and with a thermochromatographic separation method is presented. The application of such procedures to the investigation of new and already known short-lived nuclides is illustrated by some examples.     

Fast separations of yttrium,silver, bromine and iodine in heavy-ion-induced fission

Fast separation methods were devised for short-lived fission products embedded in Mg catcher foils; these are based on solvent extraction techniques.³⁴Cl is a major contamination problem because it is formed directly by spallation in the catcher foil. The methods for Ag, Br and I had a decontamination factor of >1000: 1 for this isotope.