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1.
Various plutonium compounds are handled in nuclear facilities of BARC. Hence, there is a possibility of occupational workers
getting exposed to Pu. In vitro bioassay monitoring in which Pu is separated by chemical procedures from excreta samples and
estimated by alpha-spectrometry, is the method of choice for the evaluation of internal dose to the occupational workers handling
Pu. However, this method requires a suitable Pu tracer for reducing the uncertainties due to chemical yield in the separation,
electro-deposition and counting efficiency. 242Pu is commonly used as a tracer but due to its non-availability, efforts were made earlier to indigenously synthesis 236Pu by proton irradiation of 237Np in BARC-TIFR pelletron facility. The present study, reports the feasibility of using 236Pu as a radiochemical yield monitor (tracer) in bioassay samples. 相似文献
2.
Various plutonium compounds are handled in nuclear facilities of BARC. Hence, there is a possibility of occupational workers
getting exposed to Pu. In vitro bioassay monitoring in which Pu is separated by chemical procedures from excreta samples and
estimated by alpha-spectrometry, is the method of choice for the evaluation of internal dose to the occupational workers handling
Pu. However, this method requires a suitable Pu tracer for reducing the uncertainties due to chemical yield in the separation,
electro-deposition and counting efficiency. 242Pu is commonly used as a tracer but due to its non-availability, efforts were made earlier to indigenously synthesis 236Pu by proton irradiation of 237Np in BARC-TIFR pelletron facility. The present study, reports the feasibility of using 236Pu as a radiochemical yield monitor (tracer) in bioassay samples. 相似文献
3.
Primary coolant samples from a research have been analyzed for239,240Pu,238Pu,238U,237Np and239Np. The determination of237Np and238U was carried out with the help of isotope dilution neutron activation analysis with239Np or238Np as tracer. For determination of239,240Pu and238Pu alpha spectroscopic isotope dilution analysis with238Pu as tracer was used.239Np was determined with the help of isotope dilution analysis using238Np as tracer. Nuclides were isolated by chemical separation on anionite resin. Before measurement, Pu isotopes were electrolytically deposited on stainless steel plates. Activity ratios referred to238U were reported. They are helpful for identification of the sources of actinide activity in reactor effluents. 相似文献
4.
Qingjiang Chen H. Dahlgaard S. P. Nielsen A. Aarkrog 《Journal of Radioanalytical and Nuclear Chemistry》2002,253(3):451-458
A procedure has been developed using 242Pu as tracer for simultaneous determination of 237Np and 239,240Pu in environmental samples. The validity of the method has been demonstrated by ICPMS and a-spectroscopy for up to 10 gram soil and sediment, seawater up to 200 litres. The paper describes a suitable chemical procedure for Np and Pu including a quantitative pre-concentration of neptunium and plutonium, preparation of Np4+ and Pu4+, Np(NO3)6
2- and Pu(NO3)6
2-. The ratio of 237Np/242Pu (or 237Np/239Pu) before and after the procedure has been determined using 10 g soil (free from Np and Pu) R
before/R
after = 1.004±3.3% (S.D n = 20) and 1 litre seawater R
before/R
after = 1.019±1.9% (S.D., n = 12). Results from the intercomparison samples IAEA-135, IAEA-381 and from environmental samples are presented. 相似文献
5.
Literature data on distribution ratios (Dw) of Np(V) and Pa(V) for the AG1-X8 resin are scarce whereas those related on resin capacity factors (k′) values for TEVA, TRU and U/TEVA resins are absent. Therefore, batch extraction experiments for Pa(V) and Np(V) from HCl and HNO3 media were realized, at tracer scale, with AG1-X8 and EIChroM resins (TEVA, TRU and U/TEVA). Based on the new Dw and k′ values obtained in this study, a new protocol for Pa/Np separation has been developed leading to a better separation factor of 105 and a chemical yield of 97 ± 3% and 99 ± 1% for Pa and Np, respectively. A separation of 231Pa from uranium matrix was successfully tested. 相似文献
6.
Christoph Genreith Matthias Rossbach Eric Mauerhofer Tamás Belgya Guido Caspary 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):699-703
Several samples of 237Np and 242Pu were irradiated in the guided cold neutron beam of the prompt gamma activation analysis facility at the Budapest Research Reactor. The thermal neutron capture cross sections of 237 Np and 242Pu were evaluated from the obtained prompt and delayed gamma ray data. The thermal neutron capture cross sections for 237Np(n,γ)238Np was found to be $ \sigma_{0} ({}^{237}{\text{Np}}) = 170.4 \pm 7.4\,{\text{b}} $ and for 242Pu(n,γ)243Pu to be $ \sigma_{0} ({}^{242}{\text{Pu}}) = 19.6 \pm 3.9\,{\text{b}} $ . 相似文献
7.
Inductively coupled plasma mass spectrometry (ICPMS), particularly with sector field mass analyzers (SF-ICPMS), has emerged in the past several years as an excellent analytical technique for rapid, highly sensitive determination of transuranic elements (TRU) in environmental samples. SF-ICPMS has advantages of simplicity of sample preparation, high sample throughput, widespread availability in laboratories worldwide, and relatively straightforward operation when compared to other competing mass spectrometric techniques. Arguably, SF-ICPMS is the preferred technique for routine, high-throughput determination of 237Np and the Pu isotopes, excepting 238Pu, at fg-pg levels in environmental samples. Many research groups have now demonstrated the SF-ICPMS determination of 239 + 240Pu activities, 240Pu/239Pu and other Pu atom ratios in several different application areas. Many studies have examined the relative contribution of global fallout vs. local/regional Pu sources in the environment through measurement of 240Pu/239Pu and, in some cases, 241Pu/239Pu and 242Pu/239Pu. “Stratospheric fallout”, which was deposited from thermonuclear tests, conducted largely during the 1952–1964 time period, is characterized by a well-defined 240Pu/239Pu of ~ 0.18, while most other sources have different ratios. Examples of local/regional Pu sources are the Nevada Test Site, the Chernobyl plume, and accidents at Palomares, Spain and Thule, Greenland. The determination of Pu activities and atom ratios has stimulated much interest in the use of Pu as a marine tracer; several studies have shown that Pu is transported over long distances by ocean currents. 240Pu/239Pu ratios > 0.20 in sediments and seawater of the North Pacific are ascribed to ocean current transport of fallout from the Pacific Proving Ground. In nuclear forensics, much effort is focused on detection and fingerprinting of small amounts of TRU in environmental samples consisting of bulk material or individual isolated particles. Activity measurements of 239 + 240Pu, determined by SF-ICPMS, have the potential to supplement and/or replace 137Cs as a tracer of erosion, deposition, and sedimentation. Undoubtedly, the application of SF-ICPMS in TRU analysis will continue to expand, witness new developments, and generate interesting unforeseen applications in upcoming years. 相似文献
8.
J. La Rosa J. Gastaud L. Lagan S.-H. Lee I. Levy-Palomo P. P. Povinec E. Wyse 《Journal of Radioanalytical and Nuclear Chemistry》2005,263(2):427-436
Summary A procedure is described to extend the current radiochemical method of seawater analysis for Pu and Am including Np. Short-lived 239Np tracer was prepared by separation from its 243Am parent. Irish Sea Water reference material (IAEA-381) containing known concentrations of 237Np, Pu isotopes and 241Am was used to test the procedure for small water volumes. Inductively-coupled plasma mass spectrometry (ICP-MS) was used in addition to alpha spectrometry for measurement of 237Np in the purified final Np fractions. 相似文献
9.
A method is described for the determination of 239Np in natural uranium metal foils irradiated in a zero-energy reactor. The foils are dissolved in nitric acid in the presence of 237Np used for the determination of the yield of 239Np. Neptunium is co-precipitated with lanthanum fluoride; lanthanum and thorium are removed by anion exchange in hydrochloric acid solution, and the neptunium is further purified by anion exchange in nitric acid solution. Sources for counting are prepared by direct evaporation of an aqueous solution onto a stainless steel disc. No corrections are necessary to the 237Np α-count for absorption in the source. The method does not necessitate prior separation of daughter 233Pa from the 237Np tracer and gives sources of high purity in good yield. 相似文献
10.
The237Np content of238Pu or239Pu samples were determined by the gammaspectrometry of238Np formed by thermal neutron activation. The measurements were carried out on irradiated238Pu samples directly, and after the chemical separation of239Pu samples. The237Np content of natural uranium was determined from the ratio of the alpha-activities of238Pu and239Pu isotopes formed from the decay of neptunium isotopes produced by the activation of237Np and238U isotopes, respectively.
相似文献
11.
Sherrod L. Maxwell Brian A. Culligan Vernon D. Jones Sheldon T. Nichols Gary W. Noyes 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(1):223-230
A new method that allows rapid preconcentration and separation of plutonium and neptunium in water samples was developed for the measurement of 237Np and Pu isotopes by inductively-coupled plasma mass spectrometry (ICP-MS) and alpha spectrometry. 238U can interfere with 239Pu measurement by ICP-MS as 238UH+ mass overlap and 237Np via peak tailing. The method provide enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then moving Pu to DGA resin for additional removal of uranium. The decontamination factor for uranium from Pu is almost 100,000 and the decontamination factor for U from Np is greater than 10,000. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration is performed using a streamlined calcium phosphate precipitation method. Purified solutions are split between ICP-MS and alpha spectrometry so that long and short-lived Pu isotopes can be measured successfully. The method allows for simultaneous extraction of 20 samples (including QC samples) in 4?C6 h, and can also be used for emergency response. 239Pu, 242Pu and 237Np were measured by ICP-MS, while 236Pu, 238Pu, and 239Pu were measured by alpha spectrometry. 相似文献
12.
S. Salminen J. Paatero P. Roos K. Helariutta 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):405-413
Activity concentrations of 237Np in peat and lichen samples in Finland were determined and contributions from nuclear weapons testing in 1950–1960s and
the Chernobyl accident were estimated. 237Np was determined with ICP-MS using 235Np as a tracer. Activity concentrations of 237Np in peat samples varied between 1.98 ± 0.05 and 14.1 ± 0.3 mBq/m2. The contribution from the Chernobyl accident to the total 237Np deposition in peat was 0.1–13%, the Chernobyl-derived fraction of total 237Np in peat being much lower than the previously determined corresponding Chernobyl-derived fractions of 239+240Pu, 241Pu, 241Am and 244Cm. 相似文献
13.
Donatella Desideri Laura Feduzi Maria Assunta Meli Carla Roselli 《Microchemical Journal》2011,97(2):264-268
Environmental contamination by artificial radionuclides and the evaluation of their sources require precise isotopic analysis and accurate determination of actinide elements above all plutonium and americium. These can be achieved by alpha spectrometry or by inductively coupled plasma mass spectrometry (ICP-MS) after chemical separation. In the present work, a simple, rapid method has been developed for the sequential separation of actinide elements from aqueous solutions and their determination by alpha spectrometry. Extraction chromatography was applied to the separation of 241Am, 244Cm, 239 + 240,238Pu, 237Np and 238,235,234U using microporous polyethylene supporting tri-n-octylamine as the stationary phase and hydrochloric acid with and without reducing agents as the mobile phase. Actinide in 9 M HCl solution is introduced into the anion exchange column; Pu (IV), Np (IV) and U(VI) are retained on the column while Am (III) and Cm passed through. Pu is eluted first, reductively, after which, Np and then U are eluted. The method can be applied to all aqueous solutions which do not contain strong complexing or precipitation agents for the elements considered. 相似文献
14.
A new rapid separation method that allows separation and preconcentration of actinides in urine samples was developed for the measurement of longer lived actinides by inductively coupled plasma mass spectrometry (ICP-MS) and short-lived actinides by alpha spectrometry; a hybrid approach. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration, if required, is performed using a streamlined calcium phosphate precipitation. Similar technology has been applied to separate actinides prior to measurement by alpha spectrometry, but this new method has been developed with elution reagents now compatible with ICP-MS as well. Purified solutions are split between ICP-MS and alpha spectrometry so that long- and short-lived actinide isotopes can be measured successfully. The method allows for simultaneous extraction of 24 samples (including QC samples) in less than 3 h. Simultaneous sample preparation can offer significant time savings over sequential sample preparation. For example, sequential sample preparation of 24 samples taking just 15 min each requires 6 h to complete. The simplicity and speed of this new method makes it attractive for radiological emergency response. If preconcentration is applied, the method is applicable to larger sample aliquots for occupational exposures as well. The chemical recoveries are typically greater than 90%, in contrast to other reported methods using flow injection separation techniques for urine samples where plutonium yields were 70-80%. This method allows measurement of both long-lived and short-lived actinide isotopes. 239Pu, 242Pu, 237Np, 243Am, 234U, 235U and 238U were measured by ICP-MS, while 236Pu, 238Pu, 239Pu, 241Am, 243Am and 244Cm were measured by alpha spectrometry. The method can also be adapted so that the separation of uranium isotopes for assay is not required, if uranium assay by direct dilution of the urine sample is preferred instead. Multiple vacuum box locations may be set-up to supply several ICP-MS units with purified sample fractions such that a high sample throughput may be achieved, while still allowing for rapid measurement of short-lived actinides by alpha spectrometry. 相似文献
15.
Sz. Osváth N. Vajda Zs. Molnár 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):461-465
A combined radiochemical separation method has been developed that enables the simultaneous determination of 234U, 235U, 238U, 237Np, 239,240Pu, 238Pu, 241Am, 242Cm, and 244Cm in medium and low level liquid radioactive wastes. The main steps of the method are sample destruction, co-precipitation
on iron(II)-hydroxide and calcium-oxalate, separation by extraction chromatography using supported dipentyl-pentyl phosphonate
(UTEVA) and supported N,N-octylphenyl-di-i-butylcarbamoylmethyl phosphine oxide with tributyl phosphate (TRU), and α source preparation. The key parameter
of the method is the adjustment of the oxidation states of the actinoides before adding the sample onto the UTEVA column.
It has been determined that (NH4)2S2O8 can be used for oxidation state adjustment resulting sufficient chemical yields. 相似文献
16.
A simple method was developed to separate Pu and Am using single column extraction chromatography employing N,N,N′,N′-tetra-n-octyldiglycolamide (DGA) resin. Isotope dilution measurements of Am and Pu were performed using accelerator mass spectrometry (AMS) and alpha spectrometry. For maximum adsorption Pu was stabilized in the tetra valent oxidation state in 8 M HNO3 with 0.05 M NaNO2 before loading the sample onto the resin. Am(III) was adsorbed also onto the resin from concentrated HNO3, and desorbed with 0.1 M HCl while keeping the Pu adsorbed. The on-column reduction of Pu(IV) to Pu(III) with 0.02 M TiCl3 facilitated the complete desorption of Pu. Interferences (e.g. Ca2+, Fe3+) were washed off from the resin bed with excess HNO3. Using NdF3, micro-precipitates of the separated isotopes were prepared for analysis by both AMS and alpha spectrometry. The recovery was 97.7 ± 5.3% and 95.5 ± 4.6% for 241Am and 242Pu respectively in reagents without a matrix. The recoveries of the same isotopes were 99.1 ± 6.0 and 96.8 ± 5.3% respectively in garden soil. The robustness of the method was validated using certified reference materials (IAEA 384 and IAEA 385). The measurements agree with the certified values over a range of about 1–100 Bq kg−1. The single column separation of Pu and Am saves reagents, separation time, and cost. 相似文献
17.
J. Aaltonen V. D. Dmitriev E. A. Gromova S. -J. Heselius V. A. Jakovlev 《Journal of Radioanalytical and Nuclear Chemistry》1996,203(1):67-77
The cross sections for the3He induced nuclear reactions on237Np leading to the formation of236sNp,238Np,236Pu,237Pu,238Pu,237Am and239Am were studied by the irradiation of thin and thick targets of237Np. The cross sections were determined in the energy range of 20–26 MeV using the stacked-foil technique with thin targets. The cross sections were used for the calculation of the thick-target yields for the production of236Pu,237Pu and238Pu from237Np irradiated with3He2+ ions in the energy range of 20–26 MeV. 相似文献
18.
J. La Rosa I. Outola E. Crawford S. Nour H. Kurosaki K. Inn 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(1):11-18
A radiochemical procedure is described for the measurement of 0.1 Bq 237Np in a solution containing similar activity concentrations of Th, U, Pu and Am as well as activity concentrations of 60Co, 90Sr and 137Cs one hundred times higher. A tracer of 239Np (milked from 243Am) was used as an isotopic spike for chemical yield determination. The relationship between gamma-counting geometries for
ampoule (liquid) and NdF3 (solid) 239Np sources was established so that Np chemical yields could be measured by a comparative method. Efficiencies of alpha-spectrometers
for 237Np in NdF3 sources were measured by a bootstrap technique. Two sets of experiments were designed and used to test out the procedure. 相似文献
19.
P. Tavčar B. Smodišs L. Benedik 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(3):593-596
An analytical procedure for the determination of activation products 238Pu, 241Pu, 239Pu/240Pu, 241Am, 237Np, and a fission product 90Sr in radioactive wastes is presented. Samples were decomposed using Fenton’s reaction. The separation was performed by anion-exchange
chromatography, extraction chromatography, using TRU and Srresin, and precipitation techniques, followed by α-spectrometry
and LSC counting. Tracer solutions and pure ion exchange resins were used to prepare artificial samples and trace nuclides
during the analytical procedure. Some real samples of spent ion-exchange resins originating from our TRIGA Mark II research
reactor were analyzed. 相似文献
20.
Donard OF Bruneau F Moldovan M Garraud H Epov VN Boust D 《Analytica chimica acta》2007,587(2):170-179
Among the transuranic elements present in the environment, plutonium isotopes are mainly attached to particles, and therefore they present a great interest for the study and modelling of particle transport in the marine environment. Except in the close vicinity of industrial sources, plutonium concentration in marine sediments is very low (from 10−4 ng kg−1 for 241Pu to 10 ng kg−1 for 239Pu), and therefore the measurement of 238Pu, 239Pu, 240Pu, 241Pu and 242Pu in sediments at such concentration level requires the use of very sensitive techniques. Moreover, sediment matrix contains huge amounts of mineral species, uranium and organic substances that must be removed before the determination of plutonium isotopes. Hence, an efficient sample preparation step is necessary prior to analysis. Within this work, a chemical procedure for the extraction, purification and pre-concentration of plutonium from marine sediments prior to sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) analysis has been optimized. The analytical method developed yields a pre-concentrated solution of plutonium from which 238U and 241Am have been removed, and which is suitable for the direct and simultaneous measurement of 239Pu, 240Pu, 241Pu and 242Pu by SF-ICP-MS. 相似文献