Sorption of144Ce(III) and147Pm(III) on hydrated iron sesquioxide

The sorption of¹⁴⁴Ce(III) and of¹⁴⁷Pm(III) on hydrated iron sesquioxide suspension and the sorption of¹⁴⁴Ce(III) on hydrated iron sesquioxide in a laboratory column were studied. The dependence of the sorption on pH and time, the sorption isotherm, the temperature-dependence of sorption, and the effects of ionic strength on sorption and desorption were determined under static conditions. The maximum sorptions of¹⁴⁴Ce(III) and¹⁴⁷Pm(III) were reached at pH=7.4 (K_d=8.9·10⁵) and pH=9.1 (K_d=6.2·10⁵), respectively.     

Yields of rare earth fission products in the spontaneous fission of californium-252

Cumulative fission yields of rare earth isotopes have been determined in the spontaneous fission of²⁵²Cf by fast radiochemical separation and gamma-ray spectrometry. The determined yield values are compared with the available literature data. The yield values for¹⁴⁷Nd,¹⁵¹Nd and¹⁵¹Pm differ from the reported values. The yield for¹⁴⁵Ce is determined for the first time.     

Separation of182Ta from biological material by precipitating it as tantalum phosphate

The method of the separation of¹⁸²Ta from urine and stool by precipitating as tantalum phosphate was elaborated. The conditions of Ta phosphate precipitation as well as coprecipitation of⁴⁵Ca,¹⁰⁶Ru,¹⁴⁴Ce,¹⁴⁷Pm,¹⁵²Eu,⁶⁰Co,⁹⁰Sr,⁹⁰Y,⁹⁵ Zr,⁹⁵Nb and U were studied. The results show that tantalum can be separated from all macrocomponents of the mineralized biological material and from the great number of radionuclides which can be present in the sample.     

Radioanalytical determination of137Cs and89Sr in milk

Separation of Cs, Sr and Ca from their mixture was studied using solvent extraction and ion exchange techniques. More than 90% separation efficiency was achieved for Ca–Sr separation using ion exchange resin (Doulite C-20) while solvent extraction amounted to 88%. A proposed technique for determination of¹³⁷Cs and⁸⁹Sr in milk (after removal of organic matter) showed more than 80% accuracy for⁸⁹Sr determination and more than 90% for¹³⁷Cs determination.     

Determination of fission-products and actinides in the Black Sea following the Cherynobyl accident

Radiochemical procedures are discussed for the isolation and determination of a suite of radionuclides in samples from the Black Sea following their input from the Chernobyl reactor accident. The samples analyzed include discrete water samples and both suspended and dissolved phases collected by in-situ chemisorption techniques. The radiochemical scheme permits the separation and analysis of¹³⁴Cs,¹³⁷Cs,⁹⁰Sr,¹⁴⁴Ce,¹⁴⁷Pm,¹⁰⁶Ru,²³⁹Pu,²⁴⁰Pu, and in some instances²⁴²Cm,²³⁸Pu, and²⁴¹Am. The detection techniques employed include various instrumental gamma spectrometric methods, low-level beta counting, alpha spectrometry, and mass spectrometry.The method's developments are described and data are presented on some representative samples from the Black Sea. The sensitivity of the analysis for the various nuclides and sample types is summarized and questions of radiochemical interferences are addressed.     

Efficiency data for some beta emitter sources in definite chemical form versus thickness

Beta detection efficiency curves are reported for some radionuclides of interest (⁴⁰K,⁹⁰Y,⁹⁰Sr+⁹⁰Y,¹³⁷Cs,¹⁴⁴Ce+¹⁴⁴Pr,¹⁴⁷Pm,¹⁵⁵Eu and²⁰⁴Tl) contained in sources of a suitable material and having a superficial density ranging from 3 to 110 mg/cm²; the curves were experimentally drawn by measuring the reference sources in different geometries by means of three GM window detectors (one of them with low background) and of a 2π flow proportional counter. These curves have been used for several years in the Radiochemistry Service Laboratories to determine radionuclides in sources of different thickness obtained by specific radiochemical separations from various environmental samples.     

Bestimmung des Gehaltes an90Sr und89Sr in Proben tierischer und pflanzlicher Herkunft

A method is described for the determination of⁸⁹Sr and⁹⁰Sr in samples of plant and animal origin. The Rehak-Feddersen method was modified to measure⁹⁰Sr. Modification was made in the sample preparation and in the toluene-HDEHP [di(2-ethylhexyl)phosphoric acid] extraction. After the extraction of yttrium, strontium is separated with nitric acid and—calculating with a correction factor—⁸⁹Sr can directly be determined. Namely,⁸⁹Sr can be measured in an aqueous solution by a liquid scintillation technique with an efficiency of 30% while⁹⁰Sr with 1.4% only. Quenching of the solution—depending on the composition—which may influence the measurement of⁹⁰Y and⁸⁹Sr was also examined. Detection limits and reproducibilities are given. Finally, evaluation of the experimental data is reported.      

Colloidal forms of radionuclides and their separation from water solution

Colloidal properties of¹⁴⁴Ce(III),¹⁴⁷Pm(III),⁹¹Y(III), and other, radionuclides were determined from the course of their self-diffusion. A reduced self-diffusion indicated the formation of colloidal radionuclides. The decrease in the self-diffusion coefficient began from a certain value of pH, and a pH region of slowest self-diffusion existed for each of the radionuclides studies. The maximum formation of colloidal radionuclides may be assumed to lie in the range of these pH values. An increase in the rate of self-diffusion was observed with radionuclides in colloidal forms under the effect of gamma-radiation. The possibility of mutual interaction between radionuclides was also inferred from the course their self-diffusion. High effective sorption of¹⁴⁷Pm(III) was attained on hydrated ferric oxide in the pH range were hydrolytic products and colloidal forms of¹⁴⁷Pm(III) were formad to a large extent.     

Sequential separation of transuranic elements and fission products from uranium metal ingots in electrolytic reduction process of spent PWR fuels

A sequential separation procedure has been developed for the determination of transuranic elements and fission products in uranium metal ingot samples from an electrolytic reduction process for a metallization of uranium dioxide to uranium metal in a medium of LiCl-Li₂O molten salt at 650 °C. Pu, Np and U were separated using anion-exchange and tri-n-butylphosphate (TBP) extraction chromatography. Cs, Sr, Ba, Ce, Pr, Nd, Sm, Eu, Gd, Zr and Mo were separated in several groups from Am and Cm using TBP and di(2-ethylhexyl)phosphoric acid (HDEHP) extraction chromatography. Effect of Fe, Ni, Cr and Mg, which were corrosion products formed through the process, on the separation of the analytes was investigated in detail. The validity of the separation procedure was evaluated by measuring the recovery of the stable metals and ²³⁹Pu, ²³⁷Np, ²⁴¹Am and ²⁴⁴Cm added to a synthetic uranium metal ingot dissolved solution.     

Seasonal variations of atmospheric210Pb and7Be concentrations at Kumamoto, Japan and their removal from the atmosphere as wet and dry depositions</p> </p>

Summary A relatively simple chemical separation procedure has been developed for the simultaneous determination of⁸⁹Sr and ⁹ 0Sractivities in water samples and on aerosol-filters of the Nuclear Power Plant (NPP) Paks origin. The procedure combines the cation-exchange chromatographic (Dowex 50 WX 8 resin) and solid phase extraction (EIChroM Sr.Spec?, DC18C6 crown ether) steps. The beta-radiation of radionuclides can be measured directly after the chemical separation by LSC. The activities of⁸⁹Sr,⁹⁰Sr and⁹⁰Y are calculated from an over determined set of equations using a method of constrained optimization technique. The equations are based on LSC measurements performed in three counting windows plus the⁹⁰Sr-⁹⁰Y decay law. The chemical yield of strontium is determined by ICP-AES. The lowest limits of detectable activity, for the measurement time of 600 minutes, are 30 mBq/sample and 18 mBq/sample for⁸⁹Sr and⁹⁰Sr, respectively.     

89Sr/90Sr-Determination in soils and sediments using crown ethers for Ca/Sr-separation

A radiochemical procedure is described for the sensitive determination of⁸⁹Sr and⁹⁰Sr activity concentrations in soil and sediment samples. After leaching the sample with hydrochloric acid, Sr is separated from most of the soluble matrix constituents and Ca by solvent extraction using dicylclohexano-18-crown-6 in trichloromethane. After backextraction with a EDTA-solution (ethylene diamine tetra acetate), Sr is purified by several precipitation steps from traces of matrix constituents and radionuclides which might interfere the beta measurements of⁸⁹Sr,⁹⁰Sr and⁹⁰Y. The detection limits are about 0.2 Bq/kg and 0.4 Bq/kg for⁹⁰Sr and⁸⁹Sr respectively. The procedure can be applied to all kind of environmental samples with small modifications of the sample preparation steps prior to analysis.     

Separation of137Cs and90Sr from mineralizates of biological materials by dicarbolide of cobalt

The distribution of some radionuclides in the course of¹³⁷Cs and⁹⁰Sr extraction and scrubbing between organic and water phase was determined.¹³⁷Cs and⁹⁰Sr were isolated from the mixture of radionuclides in mineralized biological materials. Dicarbolide of cobalt i. e. 3,3′-commo-bis[undecahydro-1,2-dicarbo-3-closo-dodecaborate] was used as an extracting agent. Quantities of the extracted radionuclides were determined by gamma spectrometric technique. Single and repeated extraction of⁹⁰Sr with 0.01M resp. 0.1M dicarbolide of cobalt in nitrobenzene and scrubbing of coextracted radionuclides by 0.5M HNO₃ were studied. The extraction of⁹⁰Sr was investigated from solutions of a hydrofobizing agent in the same way. Finally, the quantitative extraction of¹³⁷Cs followed by the extraction of⁹⁰Sr from mixtures of radionuclides in a mineralized biological material was studied. Extraction yields from dry and wet mineralizates of biological tissues, from urine and milk were compared. Suitable working conditions for the separation procedures were selected.     

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.     

Emulsion liquid membrane extraction of fission products promoted by polyvalent and organic acids

Emulsion liquid membranes (ELM) with di-2-ethylhexylphosphoric acid in n-alkane, and dipicrylamine and cobalt(III) dicarbollide in nitrobenzene stabilized in double emulsions by SPAN 80/85 surfactant were used for preconcentration of radioactive fission products (¹³⁷Cs,⁹⁰Sr,¹³⁹Ce, and¹⁵²Eu) from slightly acidic nitrate solutions. The efficiency of sulfuric, phosphotungstic and silicotungstic acids as stripping agents, and picric acid as the bulky anion additive was investigated. A group separation of the fission products is possible by the ELM technique and can be considered for their removal from waste water solutions.     

Artificial radioactive contamination of sediment samples along the Romanian sector of the Danube river and the Black Sea coast

The concentrations of¹³⁷Cs were determined by in 11 sediment samples, collected along the Romanian sector of the Danube river and the Black Sea coast during 1994 γ-ray spectrometry. The concentrations of⁹⁰Sr in the same sediment samples were determined by β-counting of the⁹⁰Y oxalate, precipitated after strontium separation using a strontium extraction chromatography column. The concentration distributions of¹³⁷Cs and⁹⁰Sr are compared with the²³⁸Pu and^239,240Pu concentration distributions in the same samples, reported in a previous paper. The accumulation potential of¹³⁷Cs,⁹⁰Sr and plutonium isotopes in the river and sea sediments analysed is discussed.     

Separation of bulk Y from 89Y(n,p) produced 89Sr by extraction chromatography using TBP coated XAD-4 resin

⁸⁹Sr was produced using the ⁸⁹Y(n, p) ⁸⁹Sr reaction by irradiating yttria target in the fast breeder test reactor (FBTR). An analytical scale procedure was standardized for the removal of the bulk target yttrium by solvent extraction using the tri-n-butyl phosphate (TBP). The final purification of ⁸⁹Sr source was carried out by ion exchange chromatography. However, extraction chromatography is preferred to solvent extraction due to its low waste generation and ease of operation. This paper reports the separation of Sr from bulk Y and other radioactive impurities produced during irradiation by extraction chromatography using TBP coated XAD-4 resin. Initially the separation procedure was standardized using ⁸⁵Sr and ⁸⁸Y tracers. The ⁸⁹Sr in the dissolver solution of the irradiated yttria target was separated under the same standardized conditions. The study established the separation of Sr from Y in the dissolver solution of the irradiated target yttria by the TBP coated XAD-4 column. However the evaluation of the column after every use for about three separation studies exhibited the reduction in its breakthrough capacity for yttrium.     

Extraction of some lanthanides by nitrobenzene solutions of dicarbolide in the presence of 18-crown-6

The extraction of¹⁴⁴Ce and^152,154Eu microamounts by nitrobenzene solutions of bis-1,2-dicarbollylcobaltate in the presence of 18-crown-6 from aqueous solutions of nitric acid has been investigated. The protonisation constants of 18-crown-6 in water and in nitrobenzene were determined and the corresponding equilibrium constants for cerium and europium extraction were evaluated.     

Improvements to arapid method for separating strontium from liquid milk by treatment with a chelating resin and crown ethers

In an attempt to improve on a previously reported method¹ for rapidly isolating Sr from liquid milk, the following investigations have been carried out: (1) elution of strontium from a chelating resin with dilute nitric acid, (2) separation of strontium from calcium by extracting from this eluate into chloroform solutions of dicyclohexyl-18-crown-6 (DC18C6), (3) transfer of the strontium into aqueous solution, and (4) removal of barium from this solution by extracting into dichloromethane solutions of 21-crown-7 (21C7). Based on the findings of these studies, a separation scheme was proposed and tested by participating in an interlaboratory comparison on the analysis of⁸⁹Sr and⁹⁰Sr in skimmed milk. The separation scheme requires about 3 hours, provides strontium recoveries greater than 90%, and ensures adequate decontamination factors for the nuclides that occur in milk.     

The separation of daughter nuclides from90Sr−90Y and140La−140Ba systems by thin-layer chromatographic methods

The separation of daughter nuclides in the carrier-free state from⁹⁰Sr?⁹⁰Y and¹⁴⁰Ba?¹⁴⁰La aqueous solution systems was performed by thin-layer chromatographic methods. (1) When a silica gel adsorbent and a developer of 1N NaCl, KCl, NH₄Cl, CaCl₂, SrCl₂ or BaCl₂ solutions was employed,⁹⁰Y and¹⁴⁰La were retained at the origin, while⁹⁰Sr and¹⁴⁰Ba advanced with the developer front. Addition of gypsum as binder to the silica gel prevented the separation of the¹⁴⁰Ba?¹⁴⁰La system, retaining both components at the origin. (2) When the¹⁴⁰Ba?¹⁴⁰La system was developed with water on a silica gel adsorbent containing 5% of gypsum, which was treated with various concentrations of nitric acid, the Rf value of¹⁴⁰La increased with the concentration of nitric acid used, reaching a maximum of 0.98 at 0.1 N. The Rf value then decreased on the further increase of the concentration of nitric acid. When the same process was applied to the⁹⁰Sr?⁹⁰Y system, there was no separation. The radiochemical purities of⁹⁰Y and¹⁴⁰La obtained in the above two ways were more than 99%.     

Fixation of radioactive isotopes on bentonite as radioactive waste treatment step

Fixation of¹³⁷Cs,¹⁴⁴Ce,⁶⁰Co,⁹⁰Sr,²⁴⁰Th and²³³U from aqueous and phosphate media on bentonite clay was studied. The fixation of the radioactive ions on bentonite surfaces was dependent on the pH behavior of the metal ions. A method was proposed to use bentonite as an absorbent of ions from simulated radioactive waste as a treatment step.