Rapid method for determination of plutonium, americium and curium in large soil samples

The analysis of actinides in environmental soil and sediment samples is very important for environmental monitoring. There is a need to measure actinide isotopes with very low detection limits. A new, rapid actinide separation method has been developed and implemented that allows the measurement of plutonium, americium and curium isotopes in large soil samples (100–200 g) with high chemical recoveries and effective removal of matrix interferences. This method uses stacked TEVA Resin®, TRU Resin® and DGA-Resin® cartridges from Eichrom Technologies (Darien, IL, USA) that allows the rapid separation of plutonium (Pu), americium (Am), and curium (Cm) using a single multi-stage column combined with alpha-spectrometry. The method combines an acid leach step and innovative matrix removal using cerium fluoride precipitation to remove the difficult soil matrix. This method is unique in that it provides high tracer recoveries and effective removal of interferences with small extraction chromatography columns instead of large ion-exchange resin columns that generate large amounts of acid waste. By using vacuum box cartridge technology with rapid flow rates, sample preparation time is minimized.     

Simultaneous determination of neptunium,plutonium, americium and curium using coprecipitation with bismuth phosphate

Radiochemical studies of the coprecipitation behaviour of neptunium, plutonium, americium and curium with bismuth phosphate were carried out on the basis of the effect of the following variables: kinds of acid, acidity, and amounts of bismuth and coexisting other elements. Simultaneous determination of the actinide elements using the coprecipitation was accomplished by adding 1 mg of bismuth at 0.2M phosphoric acid and by direct measurement of alpha spectrum of the precipitates. The order of the coprecipitation yields of the elements was also discussed by the difference of both the oxidation states and sulfate complex formation.     

Determination of plutonium,americium and curium in environmental meterials

A sequential radiochemical scheme for the separation of Pu and Am (along with Cm) from environmental materials is given. Optimum conditions for coprecipitation of these elements on bismuth phosphate and the influence of Fe and Th content of the sample on the recovery of Am were studied. Internal tracers²⁴²Pu and²⁴³Am were used as tracers for Pu and Am, respectively, and estimates were made by alpha-spectrometry. Average recoveries obtained from sea water were 85% and 77% for Pu and Am, respectively. Lower recoveries (<50%) were obtained for Am in sediments. Work carried out as part of the International Atomic Energy Agency Research Contract 1954/RB/RI.     

Determination of plutonium,americium and curium in airborne effluents of nuclear power plants

A radiochemical method has been developed for the determination of²³⁸Pu,^{239, 240}Pu,²⁴¹Am,²⁴²Cm and²⁴⁴Cm in airborne effluents of nuclear power plants. The method involves conversion of transuranium elements to acid-soluble forms, dissolution, purification, electrodeposition and alpha spectrometric determination. Final recovery ranged from 69.0 to 75.4% for plutonium and from 26.8 to 68.3% for americium and curium.     

Sequential separation of neptunium,plutonium, americium and curium using coprecipitation with bismuth phosphate

The reaction of neptunium, plutonium and americium with oxidizing or reducing agents in phosphoric acid solution has been studied to design a separation procedure of the actinide elements using coprecipitation with bismuth phosphate. In the presence of uranium, successive separation of neptunium, plutonium, americium and curium was accomplished by combining the coprecipitation and redox reaction of the elements. The coprecipitation behaviour of fission products during the course of sequential separation of the actinide elements on bismuth phosphate was also discussed.     

New fecal method for plutonium and americium

A new fecal analysis method that dissolves plutonium oxide was developedat the Westinghouse Savannah River Site. Diphonix Resin . (Eichrom Technologies),is used to pre-concentrate the actinides from digested fecal samples. A rapidmicrowave digestion technique is used to remove the actinides from the DiphonixResin ., which effectively extracts plutonium and americium from acidic solutionscontaining hydrofluoric acid. After resin digestion, the plutonium and americiumare recovered in a small volume of nitric acid that is loaded onto small extractionchromatography columns, TEVA Resin and TRU Resin (Eichrom Technologies). Themethod enables complete dissolution of plutonium oxide and provides high recoveryof plutonium and americium with good removal of thorium isotopes such as ²²⁸Th.     

Studies for simultaneous quantitative electrodeposition of plutonium and americium for alpha-spectrometry

For high resolution alpha-spectrometric studies, the sources of alpha-emitting actinides are generally prepared by electrodeposition. Usually, by electrodeposition of only one element can be achieved quantitatively. A method was developed for the simultaneous quantitative electrodeposition of plutonium and americium, in two hours using 0.005M oxalic acid with saturated ammonium chloride. The alpha-spectral characteristics of sources prepared by this method were better than those prepared by the drop deposition method. This electrodeposition procedure was validated with nuclear fuel samples containing plutonium and americium.     

Determination of plutonium,americium and curium isotopes in radioactive metal wastes deriving from nuclear decommissioning

A radiochemical analytical method, coupling different measurements techniques (alpha spectrometry, liquid scintillation counting and mass-spectrometry) for quantifying the content of the most significant plutonium and americium/curium isotopes in metal waste samples, is presented. The method based on the sequential determination of all the analytes of interest has the great advantage to perform the sample pre-treatment only once, resulting fast and cheap while maintaining sufficient selectivity and sensitivity. The mean values of radiochemical yields and the minimum detectable activities have been evaluated. Significant activity ratios between transuranic isotopes have been revealed and used to investigate the origin of the waste samples.

     

Determination of activity concentrations and activity ratios of plutonium,americium and curium isotopes in radioactive waste samples

This paper presents a rapid and quantitative radiochemical separation method for the Pu, Am and Cm isotopes with an anion exchange resin and a TRU resin. After the Pu isotopes were purified with an anion exchange resin method and the Am and Cm isotopes were purified with the TRU resin method, micro-coprecipitation method was applied for an alpha-source preparation. The activity concentrations and activity ratios for the Pu, Am and Cm isotopes in a radioactive sample were measured by radiation counting methods such as an alpha-spectrometry and a liquid scintillation counting as well as by a mass spectroscopic method such as a thermal ionization mass spectrometry.     

Rapid,quantitative analysis of americium,curium and plutonium isotopes in Hanford samples using extraction chromatography and precipitation plating

Recently developed methods for the rapid, quantitative analysis of americium (Am), curium (Cm), and plutonium (Pu) isotopes in Hanford soil, sludge, and waste-tank samples are described. After dissolution, dilutions are made as necessary based on alpha-energy analysis of a small aliquot of the original solution. Isotopic tracers are then added and Am-Cm and Pu are separated by extraction chromatography, coprecipitated with neodymium fluoride, and counted. Examples of alpha spectra are given, and results obtained for Hanford sludge samples are presented.     

Simultaneous biphasic liquid scintillation determination of americium and plutonium

A procedure for the simultaneous determination of²⁴¹Am and²³⁹Pu or²³⁸Pu was carried out in samples such as air filters, sweep-tests, aqueous solutions and urine. The method described here includes a previous treatment of the samples in accordance with the type of matrix in which the actinides are included and a liquid scintillation counting using a two-phase cocktail. The upper detection limit was estimated to be 50 mBq for a 50-minute counting time.     

A robust procedure for the determination of plutonium and americium in seawater

A new procedure for the analysis of Pu and Am in large water samples is presented. In this procedure, the actinides are first preconcentrated from 200 liter water samples with combined MnO₂ and Fe(OH)₃ co-precipitation. Pu and Am are then separated from the large amount of Mn by performing a second precipitation of Fe(OH)₃ at pH 6. The final separation of Pu and Am from interfering elements and from each other is achieved with the use of a single extraction chromatographic column of TRU-ResinÔ. The -activities are then determined using -spectrometry after source preparation by CeF₃ micro co-precipitation. The procedure described is faster, simpler, more robust and gives higher chemical yields then procedures normally used for routine analysis of Pu and Am. The chemical yields of Pu and Am, when analysing 200 liter sea water samples, are between 80-85%.     

Spectrochemical analysis of curium and americium samples

Spectrochemical procedures have been developed to determine impurities in americium and curium samples. The simultaneous separation of many impurity elements from the base material (americium and curium) is carried out with extraction and extraction-chromatographic methods using di(2-ethyl hexyl phosphoric acid (D2EHPA).

It is shown that part of the elements (alkalis, alkaline earths, silicon, tungsten, tantalum and other elements) are separated with extraction or sorption of americium and curium; the other part (rare earths, titanium, zirconium, niobium, molybdenum) with the Talspeak process.

Two fractions in the extraction chromatography and three fractions in the extraction separation of americium and curium, containing impurities, are analyzed separately by a.c. or d.c. arc spectrography. To increase the sensitivity of the spectrographic analysis and accelerate the burn-up of impurities from the crater of the carbon electrode bismuth fluoride and sodium chloride were used as chemically active substances. The extraction of impurities from weighed quantities of americium and curium samples of 5–10 mg permits the lower limit of determined impurity concentrations to be extended to 1 × 10⁻⁴–5 × 10⁻³% m/m.     

A ratio derivative spectrophotometric method for the simultaneous determination of uranium and plutonium

A ratio derivative spectrophotometric method has been developed for the simultaneous determination of uranium and plutonium at mg levels in 1M HNO₃ medium. In this method the overlapping spectra of uranium and plutonium are well resolved by making use of the first derivative of the ratios of their direct absorption spectra. The derivative ratio absorbances of uranium and plutonium are measured at 411.2 and 473.8 nm, respectively for their quantification. The method is simple, fast and does not require separation of uranium and plutonium. Another salient feature of the method is that it does not lead to generation of analytical waste thereby minimising the efforts required for the recovery of plutonium. Uranium in the conc. range of 10–25 mg/g and plutonium in the conc. range of 0.5 to 2 mg/g (U/Pu ratio varying from about 10 to 25) were determined in the same aliquot with a precision and accuracy of about 0.5% and 1%, respectively.     

A procedure for concentrating americium and curium combined with their separation from plutonium and fission products using a chelating resin

The effect of agitation time and resin quantity on the sorption of americium, curium and europium from mineral acid solutions, using a chelating resin based on aminopolystyrene and Arsenazo I was determined, and the behaviour of plutonium and fission products was investigated under optimum conditions with respect to the sorption of americium and curium. A procedure is proposed for concentrating americium and curium from dilute solutions, combined with their separation from iron, plutonium and fission products. The procedure consists of sorption on the chelating resin from 0.1–1N mineral acid solutions, washing of the resin with 0.5M oxalic acid and 11N sulfuric acid, and elution of americium and curium with 2M triammonium citrate.     

A new method for the determination of plutonium and americium using high pressure microwave digestion and alpha-spectrometry or ICP-SMS

Plutonium and americium are radionuclides particularly difficult to measure in environmental samples because they are α-emitters and therefore necessitate a careful separation before any measurement, either using radiometric methods or ICP-SMS. Recent developments in extraction chromatography resins such as Eichrom^® TRU and TEVA have resolved many of the analytical problems but drawbacks such as low recovery and spectral interferences still occasionally occur. Here, we report on the use of the new Eichrom^® DGA resin in association with TEVA resin and high pressure microwave acid leaching for the sequential determination of plutonium and americium in environmental samples. The method results in average recoveries of 83 ± 15% for plutonium and 73 ± 22% for americium (n = 60), and a less than 10% deviation from reference values of four IAEA reference materials and three samples from intercomparisons exercises. The method is also suitable for measuring ²³⁹Pu in water samples at the μBq/l level, if ICP-SMS is used for the measurement.     

Comparison of alpha-spectrometry and alpha/gamma ratio method for the determination of americium in plutonium bearing fuel materials

Determination of americium is one of the requirements of chemical quality assurance of plutonium bearing fuel materials. Alpha-spectrometry is generally used for the determination of ²⁴¹Am in Pu bearing fuels since the efficiency of semiconductor detector used for alpha-spectrometry is independent of the alpha-particle energy in the 4 to 8 MeV range. However, this method has limitations for Pu samples containing extremely small or very large amounts of ²⁴¹Am. Thus an alternative methodology based on alpha/gamma (α/γ) activity ratio was developed and tested using different samples. The method is based on the determination of total γ-activity (of 60 keV peak) of an aliquot of the solution and the total α-activity present in the aliquot. The method is fast as it does not involve chemical separation of Pu and Am as required in the alpha-spectrometric method. Data obtained on synthetic and real life samples demonstrates the usefulness of the developed alpha/gamma ratio method for the determination of ²⁴¹Am in Pu bearing fuel samples.     

Simultaneous determination of plutonium and americium in biological and environmental samples

A radiochemical method is given to determine the specific activity of²³⁸Pu, and²⁴¹Am from the global fallout in environmental and biological samples. The radiochemical recovery was for human livers Pu: 60–70%, Am: 40–60%; Bran: Pu: 50–70%, Am: 30–40%; Soil: Pu: 50–80%, Am: 30–50%. The resolution of the alpha-spectrum was for soils 30–40 keV and for livers and brans 40–60 KeV. To facilitate the wet ashing of large amounts of bran (15 kg), which are necessary to determine the presently very small activity concentrations of the transuranic elements in these types of samples, a fermentation process was employed. The procedure was tested by using NBS standard reference material and subsequently applied for the determination of Pu and Am from the global fallout in livers, plant tissues (bran), and soils.     

Simultaneous determination of plutonium and americium in soils by extraction chromatography

A radiochemical method is described for the determination of²³⁸Pu,^239(240)Pu and²⁴¹Am in a single soil sample. Plutonium is separated from a HNO₃ leaching solution by a Microthene-TNOA column; amcricium is coprecipitated by oxalic acid, decontaminated from polonium by a TNOA-column in HCl medium, separated from the rare earth elements by a Microthene-HDEHP column, eluted with a 0.07M DTPA+1M lactic acid solution and finally purified by a PMBP-TOPO extraction. The method supplies a good decontamination of Am and Pu from natural alpha emitters; starting from 50 g soil, the average yields were 75.1±13.4% for plutonium and 57.7±10.8% for Am.^239(240)Pu,²³⁸Pu and²⁴¹Am concentrations (mBq/kg) in three different kinds of soil were the following: 255, 10.4, 81.3 (uncultivated soils); 236, 11.6, 76.7 (cultivated soils); 46, 1.9, 19.8 (river sediment). The average ratios²³⁸Pu to^239(240)Pu and²⁴¹Am to^239(240)Pu were 0.044 and 0.350, respectively.