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1.
In this paper a technique to separate and measure both isotopes (237Np and 239Np) together is presented. A combined shape pulse discrimination liquid scintillation measurement with gamma-spectrometry,
permits a precise measurement after the radiochemical separation. This technique was carried out by using an Eichrom chromatographic
column (TEVA) as the first step of a more complete method, applied in the Nuclear Regulatory Authority, to separate actinides
in nuclear waste and liquid effluents. The MCA is 0.08 Bq/l by alpha-spectrometry and 0.22 Bq/l (2σ) by liquid scintillation
counting (LSC) for 93.7% of measurement efficiency and 98.4% of chemical recovery. 相似文献
2.
S. Pommé E. García-Toraño G. Sibbens S. Richter R. Wellum A. Stolarz A. Alonso 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(1):207-210
High-resolution alpha-particle spectrometry was performed on three uranium materials enriched in 235U. Besides the 235U peaks, separate peaks belonging to impurity traces of 234U could be quantified. Relying on the isotopic composition of the uranium, as determined by mass spectrometry, the ratio of
the half-lives of 238U and 235U was determined via the activity ratio of 234U and 235U in the materials. As an intermediate link, the 234U/238U half-life ratio was taken from published mass spectrometric analyses of ‘secular equilibrium’ uranium material. The resulting
half-life ratio T
1/2(238U)/T
1/2(235U) = 6.351±0.031 is in agreement with the commonly adopted half-life values determined by Jaffey et al. 相似文献
3.
Summary An extraction chromatography method was developed for the separation of 239Np from 243Am in nitric acid solution. A sorbent based on aliphatic quaternary amine Aliquat-336 and hydrophobized silica gel was prepared. 239Np reduced to the oxidation state(IV) with ferrous sulfamate in 2M or 6M HNO3 sorbs on the prepared silica gel column. After washing with 0.1M ferrous sulfamate in 2.5M HNO3, 239Np is eluted with 0.1M HNO3 containing 0.02M HF. The separation of 243Am from 239Np is very effective. The purity of 239Np was found to be better than 99.5%. The proposed 239Np milking procedure is suitable for the preparation of 239Np tracer that can be used for the determination of 237Np radiochemical yield. 相似文献
4.
Sz. Osváth N. Vajda Zs. Molnár É. Széles Zs. Stefánka 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(3):675-680
The majority of long-lived radionuclides produced in the nuclear fuel cycle can be regarded as “difficult-to-measure” nuclides,
hence chemical separation is needed before the nuclear measurement of them. A combined radiochemical procedure that enables
the simultaneous determination of some “difficult-to-measure” nuclides in medium and low level radioactive wastes has been
developed in our laboratory. Recently, this method has been extended for determination of 237Np and 93Zr. 237Np and 93Zr are pre-concentrated by co-precipitation on iron(II) hydroxide and zirconium oxide, separated by extraction chromatography
using UTEVA, and measured by inductively coupled plasma mass spectrometry (ICP-MS). As even traces of polyatomic ions and
isotopes at m/z 237 or 93 cause considerable interferences during ICP-MS detection, a purification step by extraction chromatography
was needed. Analyzing real samples (evaporation concentrates of a nuclear power plant) 66–99% and 31–99% chemical yields were
achieved for Np and Zr, respectively. 相似文献
5.
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
6.
Zsolt Varga Adrian Nicholl Erich Hrnecek Maria Wallenius Klaus Mayer 《Journal of Radioanalytical and Nuclear Chemistry》2018,318(3):1565-1571
The paper describes the age (production date) determination of uranium reference materials using the 231Pa/235U ratio. Direct addition of 237Np in secular equilibrium with its 233Pa daughter was chosen instead of the regular milking of 237Np to avoid possible loss of Pa. Sample preparation consists of a fast, one-step procedure. The developed method using ICP-MS for the measurement of 231Pa is more precise than alpha spectrometry and is applicable for freshly produced low-enriched uranium materials. The measured ages are in good agreement with the reported production dates, thus the 231Pa/235U chronometer can be applied for validation of 230Th/234U in nuclear forensics and safeguards. 相似文献
7.
Xinfeng You Shengdong Zhang Zhihong Yang Youqian Ding Anzhi Cui 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(1):267-272
101Tc is a very important nuclide as fuel burn up monitor, and its half-life value has been measured many times, however, they
were so different from each other. In this work, 101Tc liquid samples were prepared by irradiating analytical pure (NH4)6Mo7O24·4H2O solution in Miniature Neutron Source Reactor (MNSR) of China. A rapid procedure which takes only 5 min was developed to
separate 101Tc samples. The final samples were analyzed by γ-ray spectrum using high purity Germanium (HPGe) multi-channel analysis system.
The results showed that there were no peaks of other nuclides except 101Tc. The half-life of 101Tc was accurately measured with HPGe γ-detector following 306.8 keV γ-ray for about 140 min, and three methods R-value method,
iterative method and translation method were adopted to process the data. Finally, a more precise and accurate value 14.02 ± 0.01 min
was given and compared with former measured data. 相似文献
8.
Separation and purification of <Superscript>249</Superscript>Cf and <Superscript>245</Superscript>Cm
There is a need to provide radioactivity standards of the higher actinides in support of both decommissioning and remediation
activities as well as routine environmental analysis. In the case 249Cf, this will provide a useful calibration nuclide for both α-and γ-spectrometry as well as improving knowledge of the decay
scheme for this nuclide. There is anecdotal evidence to suggest that the chemical yield of americium and curium may differ
in radiochemical analysis. Thus, a chemical yield tracer of 245Cm may help to resolve this issue and will be suitable for both, suitable for use as a chemical yield tracer for both α-particle
spectrometry and mass spectrometry. An aged source of 249Cf was used as the source material for the separation of these two nuclides by cation-exchange, using 2-hydroxy-2-methyl-propanoic
acid at controlled pH as an eluant, 249Cf being eluted before the 245Cm daughter. The purity of both nuclides was measured by γ-ray spectrometry. 相似文献
9.
T. Belgya 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(3):609-614
The 14N(n,γ)15N reaction is a primary γ-ray source for high energy calibration of detectors. The relative γ-ray-intensities of 15N and the relative γ-ray detection efficiency function have been simultaneously determined up to 10 MeV from γ-peak areas
alone. Absolute γ-ray-intensities were obtained with proper renormalization to known absolute intensity. The influence of
these new intensity values are assessed for use in PGAA. Any consistently used set of calibration intensities applied in the
creation of library values and for analysis do not influence the concentrations. Contrary to this, quantities based on sums
of γ-ray cross sections may provide different answers with the new 15N intensities and they give means to validate them. 相似文献
10.
Sz. Osváth N. Vajda Zs. Stefánka É. Széles Zs. Molnár 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):459-463
A combined radioanalytical method for determination of 93Zr and 237Np (as well as other actinoids) in radioactive wastes has been developed. Analytes were co-precipitated on iron(II)-hydroxide,
separated and purified on UTEVA columns, and detected by inductively coupled plasma mass spectrometry. According to Zr and
Np, 65 and 75% yields were achieved, respectively. 相似文献
11.
D. A. Haas S. R. Biegalski K. M. Foltz Biegalski 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(3):561-565
In support of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), improvements have been made to the model of the Automated
Radioxenon Sampler/Analyzer (ARSA) β-γ coincidence detector for radioxenon monitoring. MCNPX is used to simulate the detector
response for all the electrons and photons emitted from 131mXe, 133Xe, 133mXe, 135Xe, and 137Cs signals. A MatLab code was written to incorporate the MCNPX results in the calculation of β-γ coincidence spectra. These
will aid in the development of the Spectral Deconvolution Analysis Tool (SDAT)1 and to calibrate β-γ coincidence systems. The models developed for this work include improvements over previous models in
their ability to address Compton scattering in the β-cell, and the β-distribution offset in the 31 keV γ-ray region for 133Xe. 相似文献
12.
Robert Kandlbinder Robert Schupfner Otto S. Wolfbeis 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(1):69-73
The determination of 228Ra by means of γ-spectrometry, in material containing significant quantities of 40K and Ca2+ such as bone ash results in increased values of counting uncertainty and lower limit of detection (LLD) because of a significant
contribution from the Compton continuum of 40K. However, 40K is widely removed from bone ash if 228Ra is coprecipitated with barium sulfate. As a result, the counting uncertainty and LLD are significantly reduced. A method
is presented for determination of very low activity concentrations of 228Ra. Impurities introduced by precipitation are negligible when applying high resolution γ-spectrometry. 相似文献
13.
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
14.
Karin Popa Alexandru Cecal Doina Humelnicu Ioan Caraus Camelia L. Draghici 《Central European Journal of Chemistry》2004,2(3):434-445
This study concerns the removal of the 137Cs+ and 60Co2+ β+γ-radioactive ions in Azolla caroliniana Willd. water fern. The living fern and two different types of biosorbent prepared from Azolla caroliniana were tested to remove the above-mentioned radioactive ions from dilute solutions, in the absence and in the presence of the
ionic competition. Effective 137Cs+ and 60Co2+ ions removal from low radioactive wastewaters was demonstrated. The time dependent K
d
(t) values were calculated from the absorption data. These results indicate that removal process achieved equilibrium in about
120 min and that it involves two steps: rapid and slow absorption; the active process (metabolic bioaccumulation on the living
fern) was responsible for above one half of the total removal process. A thin layer radiochromatography study leads to the
conclusion that the biochemical components in which 137Cs+ and 60Co2+ place themselves are of a polysaccharide and lipoid fractions. 相似文献
15.
Jerome J. La Rosa Jerzy W. Mietelski Eric Wyse 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):385-387
Described are results and the procedure for a pilot study on 237Np content in forest litter samples from Poland in relation to their plutonium activity. Neptunium was determined by inductively
coupled plasma mass spectrometry (ICP-MS) and Pu by alpha spectrometry. Two samples originated from a location with pure global
fallout and two others from a place with about 65% of the plutonium from Chernobyl. Plutonium activities were determined twice:
at Krakow and in Monaco. The two results were consistent and 239 + 240Pu activities ranged from about 1 to about 7 Bq/kg dry weight (dw). The chemical recovery for Np was between 27 and 89%. Results
for 237Np activity concentrations were between 0.099 ± 0.005 and 2.21 ± 0.076 mBq/kg dw. Observed activity ratios were lower than
expected and could be explained by fractionation of Np against Pu in forest litter. 相似文献
16.
I. I. Dovhyi D. A. Kremenchutskii V. Yu. Proskurnin O. N. Kozlovskaya 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(3):1643-1648
90Y was separated from 90Sr using an extraction chromatographic resin consisting of 4, 4′(5′)-bis-t-butylcyclohexano-18-crown-6 (DtBuCH18C6), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) amide (C2mimNTf2), and a polymer (Amberlite XAD-7). Ionic liquid was introduced into the column to improve the separation efficiency. The column showed an excellent performance for the separation of Y from Sr. After the separation, the ratio of 90Sr/90Y was <2.0 × 10?5; the column was recycled for >18 times. This study provides preliminary results on columns to produce 90Y with a high purity in radiopharmaceuticals. 相似文献
17.
D. A. Loginov M. M. Vinogradov Z. A. Starikova P. V. Petrovskii A. R. Kudinov 《Russian Chemical Bulletin》2007,56(11):2162-2165
The visible light irradiation of the [(η5-C6H7)Fe(η-C6H6)]+ cation (1) in acetonitrile resulted in the substitution of the benzene ligand to form the labile acetonitrile species [(η5-C6H7)Fe(MeCN)3]+ (2). The reaction of 1 with ButNC in MeCN produced the stable isonitrile complex [(η5-C6H7)Fe(ButNC)3]+ (3). The photochemical reaction of cation 1 with pentaphosphaferrocene Cp*Fe(η-cyclo-P5) afforded the triple-decker cation with the bridging pentaphospholyl ligand, [(η5-C6H7)Fe(μ-η:η-cyclo-P5)FeCp*]+ (4). The latter complex was also synthesized by the reaction of cation 2 with Cp*Fe(η-cyclo-P5). The structure of the complex [3]PF6 was established by X-ray diffraction.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2088–2091, November, 2007. 相似文献
18.
A. Amekudzie O. Adukpo J. Annkah A. Faanu G. Emi-Reynolds 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(3):795-800
As part of monitoring the exposure of the Ghanaian public to natural radioactivity, radioactivity concentrations in titanium
enamel frits use for coating, spraying and decorating steel bowls were investigated. Samples collected from Ghana Utensil
Manufacturing Company in Ghana were analyzed using γ-ray spectrometry with a high purity germanium detector. The samples were
found to contain an average absorbed dose rate of 509.38 nGy h−1, while an average annual effective dose was calculated to be 2.50 mSv. 相似文献
19.
Youjiu Zhang Yujie Xu Ran Zhu Mingjiang Hu Jianxiang Li Yuejin Chen Daojin Wang Wo Fan 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(1):3-8
This study examined the tissues distribution and pharmacokinetics of rhTNT-IL2, a fusion protein, in rats and macaques after
iv. injection. The rhTNT-IL2 was labeled with 125I. The 125I-rhTNT-IL2 was administered into rats and macaques at a dose of 250 μg·kg−1 and 125 μg·kg−1, respectively. Upon administration, rhTNT-IL2 declined in tri-exponentially with the half-lives of 1.78 h (T
1/2α), 25.06 h (T
1/2β), 114.19 h (T
1/2γ) for rats and 1.87 h (T
1/2α), 9.82 h (T
1/2β), 43.17 h (T
1/2γ) for macaques. The fraction of 125I-rhTNT-IL2 excreted in feces was low (about 1%), while the majority of 125I-rhTN-IL2 was excreted in urine. The tissue distributions showed that the liver, spleen and heart were major organs for deposition
of the fusion protein in rats and macaques in 48-hour post-injection, and the fusion protein could not penetrate through blood
brain barrier. 相似文献
20.
The estimation of the uncertainty of measurement has, nowadays, become an integral part of analytical results. The uncertainty
and efficiency of extraction and cleanup are very important components of a pesticide residue analytical method. In this work,
for a quick review of extraction and cleanup efficiency and to evaluate the individual analysis steps during method adaptation,
14C-carbaryl was applied at all fortification levels. Then, further analyses, such as ethylacetate extraction, filtration, evaporation
and cleanup, were performed. The calibration of gel chromatograph column, performed with both 14C-carbaryl and fortification mixture (dichlorvos, malathion and chlorpyrifos), showed that pesticide fractions came through
the column between the 8- and 23-mL fractions. The overall recovery of 14C-carbaryl after the extraction and cleanup step was 0.91, with the relative uncertainty of 0.084. Using the “bottom-up” approach,
the uncertainty of extraction u
cEX and cleanup u
cGPC were 0.033 and 0.107, respectively. The combined standard uncertainty u
c associated with the described analytical method was 0.112. Similar values were obtained using the alternative “top-down”
approach: uncertainty of extraction u
ct1 was 0.039, uncertainty of cleanup u
ct2 was 0.108 and the combined standard uncertainty u
cAV was 0.081. Both approaches showed that the uncertainty of cleanup was the main source of combined standard uncertainty. 相似文献