The extraction of caesium with nitrobenzene in the presence of phosphomolybdic acid

The main factors controlling the distribution of caesium between the aqueous phase and a nitrobenzene phase in presence of phosphomolybdic acid were investigated. Data on the distribution of the heteropolyacid are given. The selectivity of caesium extraction was evaluated. The possibility of separating caesium by this method for analytical purposes was demonstrated in isolating caesium from a mixture of long-lived fission products and in isolating caesium from rubidium by repeated extraction.     

Determination of fission products in nuclear samples by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS)

Determination of fission products and of their isotopic composition is of high importance for the characterisation and complete inventory of nuclear fuels. Radiometric and mass spectrometric methods, which are currently used, enable only an incomplete determination of the fission products. Radiometric methods cannot be applied to all fission products and mass spectrometric methods are hindered by the existence of isobaric interferences, therefore a previous chemical separation is required before mass spectrometric analysis. Capillary electrophoresis (CE) has been coupled with inductively coupled plasma mass spectrometry (both ICP-QMS and ICP-SFMS). Typical detection limits of 6 ng/mL and 4 pg/mL for caesium as well as 8 ng/mL and 7 pg/mL for lanthanides have been obtained by CE-ICP-QMS and CE-ICP-SFMS, respectively. In addition to these very low detection limits, the procedures present the advantages to be fast (6 min for caesium and 13 min for lanthanides, respectively), to require a low microliter range sample volume and a nanoliter range injection volume. The radiation dose for the personnel as well as the volume of nuclear liquid wastes generated during the measurements are consequently reduced.The procedures have been applied to nuclear samples from PUREX process and leachates from MOX fuels.     

The method of concentration-dependent distribution in the quantitative use of radioisotopes: Part III. The determination of submicrogram amounts of caesium by extraction with calcium dipicrylaminate into nitrobenzene

The dependence of the partition ratio of caesium between a nitrobenzene solution of calcium dipicrylaminate on the total amount of caesium in the system can be used as an analytical calibration curve. An appropriate method of isolating caesium for this determination was worked out using the polyiodide extraction of caesium. The selectivity, sensitivity and accuracy of the method were evaluated.     

Novel applications of dipicrylamine as an extractant in the determination of alkali metals

A ten-stage mixer-settler type extraction procedure has been used for the preparation of rubidium-free caesium salts. A nitrobenzene solution of (0.11M CsDPA flows counter to a purified aqueous solution of 0.05M CsCl and 10(-3)M Cs(4)(EDTA), which removes Rb, K, Na and most other metals from the organic phase. An extraction colorimetric titration procedure for 0.2-2 mg of caesium is described, and also an indirect method for determination of potassium and sodium in admixture, based upon the difference in the ability of the two ions to replace (137)Cs(+) in a nitrobenzene solution of dipicrylaminate.     

Laser atomic-ionization determination of caesium in flames

The laser atomic-ionization (AI) method has been developed for determination of caesium in flames. The limit of detection for caesium in pure aqueous solution is 4 pg ml . The interference of Li, Na, K, Rb, Ca and Fe with the AI signal of caesium has been investigated and explained. The analytical potential of this method has been demonstrated by determination of caesium in water samples, in the concentration range 0.1-1 ng ml .     

Substoichiometric separation in activation analysis: extraction of co-ordinatively-unsolvated salts

The necessary conditions have been examined for the use of extraction of coordinatively-unsolvated salts for substoichiometric separations in activation analysis, especially the influence of interfering ions and of the concentration of the carrier. A study has been made of the substoichiometric extraction of halide ions, oxyanions and anionic metal complexes by means of the tetraphenylarsonium ion into chloroform and dichloroethane, and of the extraction of alkali metal ions into nitrobenzene with tetraphenylborate. Substoichiometric extraction can be combined with neutron-activation analysis for the determination of traces of iodine, caesium, rubidium, manganese, rhenium, chromium, thallium, gold, gallium and tantalum.     

A rapid solvent extraction method for the determination of caesium-137 in environmental materials

A solvent extraction method for the quantitative determination of caesium-137 in environmental samples is described. Caesium carrier is added to the ashed sample, which is dissolved with hydrochloric acid. The solution is filtered to remove any carbon and the pH is adjusted to 2.0. Sodium dodecylbenzene sulphonate is added and the extraction is done with phenol-nitrobenzene mixture. The organic phase is washed with EDTA solution and the caesium is stripped from the washed solvent with 6 M hydrochloric acid. The caesium is precipitated as caesium chlorostannate to ensure absolute decontamination from potassium-40. Recovery from standard solution is about 85% and from vegetation, rainwater and effluent samples about 80%. The method is applicable in the presence of large quantities of interfering ions, and decontamination factors for many nuclides are greater than 10³.     

Extraction and separation of (137)cs and (86)rb by means of 4-t-butyl-2(alpha-methylbenzyl)phenol

The extraction of caesium-137 and rubidium-86 by a solution of 4-t-butyl-2(alpha-methylbenzyl)phenol in n-octane and tetrachloromethane has been investigated. The separation of rubidium and caesium has been performed by the Craig method and by reversedphase extraction chromatography.     

Determination of radiocerium in fission products by extraction chromatography using di-(2-ethylhexyl)phosphoric acid

An extraction chromatographic method is described for the determination of cerium in a fission product mixture. Cerium(IV) is separated on a column of siliconized kieselguhr saturated with di-(2-ethylhexyl)phosphoric acid (HDEHPA). After washing the column with a mixture of sodium bromate and nitric acid, cerium is eluted by a mixture of 5M HNO₃ and 0.1M ascorbic acid. The optimum conditions for the quantitative sorption and elution of cerium were found, and the reproducibility of the yield was verified. The influence of other fission and corrosion products (Mg, Fe, Al, U) on the sorption and elution of cerium was studied. The method has been successfully applied for the determination of cerium in artificial and natural mixtures of fission products.     

Synergistic extraction and spectrophotometric determination of plutonium(VI)

A rapid method for the synergistic extraction and spectrophotometric determination of plutonium(VI) in milligram amounts using a mixture of thenoyltrifluoroacetone (TTA) and tributyl phosphate (TBP) in benzene has been developed. Quantitative extraction is obtained from aqueous solutions of pH=2 affording separation from many commonly occurring impurities, viz., thorium, fission products and cladding materials. The precision and accuracy of the method has been found to be∼1%. The study of the solid product isolated from the extraction system indicates the stoichiometry of the extracted species as PuO₂(TTA)₂ TBP.     

A procedure for the determination of radioactivity due to fission product niobium

A procedure using tri-n-butyl phosphate solvent extraction has been devised and investigated for the determination of the activity due to fission product niobium. The methode gives good radiochemical purity and a standard deviation of 2% or less, except on material which has had a very short cooling time since the end of neutron irradiation.     

Separation of transplutonium and rare-earth elements by extraction with HDEHP from DTPA solutions

The extraction behaviour of Am, Cm, Bk, Cf, Es, La, Ce, Pr, Pm, Sm, Eu, Gd, Ho, Yb and Lu in the system HDEHP—DTPA in lactic acid has been studied from the point of view of group separation of the transplutonium and rare-earth elements. Optimum separation conditions have been found on the basis of the results obtained. Some test separations of transplutonium elements from rare-earth fission products have been carried out in real solutions by extraction chromatography. It has been shown that this method can be used successfully for the analytical determination of transplutonium elements as well as for recovery of the latter from irradiated samples.     

Extraction chromatographic separation of uranium and fission products in the system di-(2-ethylhexyl)phosphoric acid-hydrochloric acid

An elution scheme has been developed for obtaining separate fission product and uranium fractions using extraction chromatographic techniques with di-(2-ethylhexyl)phosphoric acid as a stationary phase and HCl of varying concentration as eluting agent. The investigations have been concentrated on the fission products cerium, europium, molybdenum and zirconium. The elution of zirconium by oxalic acid is characterized by a peak broadening and has been explained by considering extraction kinetics. Experiments on column performance with different support materials have proved Ftoroplast-4 and Celite Hyflo Super Cel to be capable of giving column fillings with equal separation ability.     

Fine structure of mass and charge distribution in low energy fission

Studies of finer details in mass and charge distribution fission leads to a better understanding of the fission process. Experimental determination of independent and cumulative yields using radiochemical techniques as well as mass spectrometers and fission product recoil separators form the basis of such studies. It has been established that closed shells as well as an even number of nucleons influence both mass and charge distributions. The magnitudes of these effects may be estimated from existing experimental yield data and various fission models. Using our measurements of several fission yields and those existing in the literature we have calculated even-odd proton and neutron effects for various low energy fissioning systems. Where enough data existed, direct calculations were made, whereas for other cases the Z_p-model of WAHL has been used. It is found that the even-odd proton effect is well established and pronounced in thermal neutron fission of²³⁵U and²³³U. Lesser effects were found for reactor neutron induced fission of²³²Th, thermal neutron fission of²³⁹Pu and spontaneous fission of²⁴⁵Cm and²⁴⁹Cf. No effect seems to exist in the thermal neutron fission of²⁴¹Pu and the spontaneous fission of²⁵²Cf. The even-odd neutron effect is found to be much lower than the corresponding proton effect in²³⁵U and²³³U fissions and is nonexistent in the rest of the fissioning systems.     

The study of sorption of caesium radionuclides by “T-55” ferrocyanide sorbent from various types of liquid radioactive wastes

The sorption of caesium by T-55 sorbent from different types of liquid radioactive wastes is studied. It is shown that the sorbent can be used for extraction of caesium from high level acidic and saline solutions and also for decontamination of caesium contaminated waters containing surfactants and EDTA.     

石墨炉原子吸收光谱法间接测定蒸汽含水率

利用石墨炉子吸收光谱法测定蒸汽发生器循环水和蒸汽冷凝水中的铯则间接测定蒸汽含水率。蒸汽含水率等于冷凝水中铯的浓度除以循环水中铯的浓度。石墨炉原子吸收光谱可以准确测定０．１ｇ／Ｌ至１ｍｇ／Ｌ浓度的铯,样品中可能存在的一些物质对测定没有干扰。本方法可以满足测定蒸汽含水率的要求,实现了数百份含水率样品的测试。     

The EURO-GANEX Process: Current Status of Flowsheet Development and Process Safety Studies

A new hydrometallurgical grouped actinide extraction process has been developed to separate the transuranic actinide ions from dissolved spent fuel solution (after an initial uranium extraction cycle). This “EURO-GANEX” process is aimed towards the homogeneous recycling of plutonium and minor actinides in a future closed fuel cycle. The separation process is based on the co-extraction of actinides and lanthanides from aqueous nitric acid into an organic phase followed by selective co-stripping of actinides. A suitable organic phase has been formulated and distribution ratios determined for lanthanides, actinides and some problematic fission products under extraction and stripping conditions. The process flowsheet has been proven on surrogate feed solutions as well as with spent fast reactor fuel; excellent recoveries of the actinides and good decontamination factors from the lanthanides and other fission products were obtained. A variation on the EURO-GANEX flowsheet (the “TRU-SANEX” process) has now been designed to produce separate Pu+Np and Am+Cm products for heterogeneous recycling. Progress on underpinning process chemistry and safety studies as well as flowsheet tests are summarized.     

Studies on the solvent extraction of technetium from thiocyanate solutions in mineral acids

Technetium-99m, separated from fission molybdenum-99, has been studied as a component of liquid-liquid phase distribution equilibria. 5-(4-Pyridyl)nonane in a carrier diluent, benzene, has been used to study the distribution of the nuclide from thermodynamically suitable aqueous phases of electrolytes with and without sterically receptive thiocyanate ions. Efficient extraction of the metal can be accomplished in a variety of aqueous phase compositions. The separation factors with respect to molybdenum, under certain experimental conditions, are fairly high. The data have been utilized to effect clean separations of technetium from molybdenum.     

The extraction of chromium(VI) from sulphuric acid solutions by 4-(5-nonyl)pyridine and its separation from fission products

4-(5-Nonyl)pyridine, a new liquid anion exchanger, has been studied for the extraction of chromium(VI) from sulphuric acid solutions. The optimal acidity is 0.1–1 M, depending on the concentration of chromium. Common anions have little effect on extraction in concentrations up to 0.1 M. Reducing agents such as ascorbic acid and thiosulphate prevent extraction at concentrations above 0.1 M. Separation of chromium(VI) from fission products was achieved.     

Massen- und Ladungsverteilung bei der Spaltung von 249Cf mit thermischen Neutronen. Vorläufige Mitteilung

The distribution of mass and charge in the thermal-neutron-induced fission of ²⁴⁹Cf has been investigated by radiochemical determination of the fission yields of 25 mass chains and one shielded nuclide (independent yield). The mass distribution is asymmetric, as in all known cases of low-energy fission. The fission yield data indicate a value of 6 ± 1.5 for v , the average number of neutrons emitted per fission. The division of nuclear charge, as indicated by the independent yield of ¹³⁶Cs, is consistent with the equal charge displacement hypothesis characteristic of low-energy fission.