共查询到20条相似文献,搜索用时 11 毫秒
1.
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
2.
T. C. Oliveira R. P. G. Monteiro A. H. Oliveira 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):497-501
The zirconium isotope 93Zr is a long-lived pure β-particle-emitting radionuclide produced from 235U fission and from neutron activation of the stable isotope 92Zr and thus occurring as one of the radionuclides found in nuclear reactors. Due to its long half life, 93Zr is one of the radionuclides of interest for the performance of assessment studies of waste storage or disposal. Measurement
of 93Zr is difficult owing to its trace level concentration and its low activity in nuclear wastes and further because its certified
standards are not frequently available. A radiochemical procedure based on liquid–liquid extraction with 1-(2-thenoyl)-3,3,3-trifluoroacetone
in xylene, ion exchange with Dowex resin and selective extraction using TRU resin has to be carried out in order to separate
zirconium from the matrix and to analyze it by liquid scintillation spectrometry technique (LSC). To set up the radiochemical
separation procedure for 93Zr, a tracer solution of 95Zr was used in order to follow the behavior of zirconium during the process by γ-ray spectrometry through measurement of the
95Zr. Then, the protocol was applied to low level waste (LLW) and intermediate level waste (ILW) from nuclear power plants.
The efficiency detection for 63Ni was used to determination of 93Zr activity in the matrices analyzed. The limit of detection of the 0.05 Bq l−1 was obtained for 63Ni standard solutions by using a sample:cocktail ratio of 3:17 mL for OptiPhase HiSafe 3 cocktail. 相似文献
3.
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
4.
5.
6.
Huang Donghui Wang Pingsheng Chen Xilin Tian Weizhi Ni Bangfa Zhang Lanzhi Zhang Guiying Liu Cunxiong Liu Likun 《Journal of Radioanalytical and Nuclear Chemistry》2005,265(3):499-503
Summary The half-life of 97Zr, used for the calculation of thermal/epithermal neutron flux ratio in k0-NAA, is re-determined using three measurement systems with different pulse processing principles. The result of 16.755±0.013 hours clarifies the discrepancy between two widely used literature values, 16.744±0.011 and 16.90±0.05 hours. Different dead-time correction methods used on various measurement systems are evaluated. Factors influencing precise measurement of relative peak counting rates are discussed in time-series measurements over a dynamic range of 1000-fold radioactive intensities (10 half-lives). 相似文献
7.
Two peptide ligands conjugated adenine, [9-N-(tritylmercapto acetyl diglycyl aminoethyl) adenine, Tr-MAG2-Ade] and [9-N-(tritylmercapto acetyl triglycyl aminoethyl) adenine, Tr-MAG3-Ade], are synthesized and labeled with 99mTc by directly labeling method. The stability of 99mTc-MAG2-adenine and 99mTc-MAG3-adenine in vitro is measured. The uptake radios of tumor to muscle at 3h post-injection are 5.70 and 4.92, respectively.
The biodistribution and scintigraphic imaging studies show that the two complexes have high localization in tumor and high
contrasted tumor images can be obtained, which suggest their potential utility as tumor imaging agents. But the high radioactivity
of abdomen could prevent the tumor imaging in this area. 相似文献
8.
Chang Heon Lee Moo Yul Suh Kwang Yong Jee Won Ho Kim 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(1):187-194
A sequential separation procedure has been developed for the determination of 99Tc, 94Nb, 55Fe, 90Sr and 59/63Ni in various radioactive wastes generated from nuclear power plants. Ion exchange and extraction chromatography were adopted
for individual separation of the radionuclides. Precipitation was supplementarily utilized for both purification of the individual
radionuclides and preparation of the radionuclide sources for use in a radioactivity measurement. The chromatographic separation
behavior of the radionuclides both from the sample matrix metals and from one another was investigated using stable metals,
Re (as a surrogate of 99Tc), Nb, Fe, Sr and Ni. The validity of the procedure for reliability and applicability was evaluated by measuring the recovery
of the metal carriers added to synthetic radioactive waste solutions. The recoveries by the chromatographic separation were
in the range of 84.8 to 102.2% with 2s of less than 8.6%, the recoveries by the precipitation being in the range of 84.3 to 97.3% with 2s of less than 10.9%. 相似文献
9.
P. Rajec L. Matel L. Drahošová V. Nemčovič 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(1):93-96
14C releases in the stack air of the NPPs V1 and V2, Jaslovske Bohunice was determined during the year 2004–2010. Radioactivity
concentration of 14C in the stack air was determined in the forms of inorganic 14CO2 and 14C
n
H
m
. The annual average activity concentration in the stacks air samples varies between 12 and 121 Bq m−3. NPP V1, starting with 45 Bq m−3 in 2005 is decreasing due to the shutting down of the reactors (the first reactor was shut down in December 2006 and the
second reactor in December 2008). The average value of radioactivity concentration for power unit V2 was 32 Bq m−3 in 2004 and reached the value of 102 Bq m−3 in the first-quarter of the 2010. The average normalized yearly discharge rates were between 0.39 and 0.64 TBq GWe−1 year−1 (2005–2008), NPP V1 and 0.19–0.61 TBq GWe−1 year−1 (2004–first-quarter 2010) for NPP V2, Jaslovske Bohunice. Most of the discharged 14C is in a hydrocarbon form, (95% for Jaslovske Bohunice NPP V2), but the CO2 fraction may reach 37% in the air stack for Jaslovske Bohunice V1. 相似文献
10.
S. K. Aggarwal D. Alamelu P. M. Shah N. N. Mirashi 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(3):771-774
Determination of 241Am/243Am ratios is required for vanous purposes including assay of Am by isotope dilution techniques. Alpha-spectrometry on electrodeposited
sources is a preferred technique for this determination. However, there is an inherent problem of tail contribution which
necessitates the use of suitable algorithms to account for the same. Recently, in the frame of a Coordinated Research Program
(CRP) of the International Atomic Energy Agency (IAEA), WinALPHA software has been developed which is a combination of an
asymmetrical Gaussian for the main part of the peak and a low energy function. Therefore, it was of interest to compare the
use of this algorithm with the routinely used method, in our laboratory, based on geometric progression (G. P.) decrease.
Since, there are no reference materials available commercially for 241Am/243Am ratios, synthetic mixtures covening a wide range (0.3 to 2.0) of 241Am/243Am α-activity ratios were used and un-ignited electrodeposited sources were prepared for α-spectrometry. The α-spectra obtained using PIPS detector, were evaluated using the two algonthms The 241Am/243Am α-activity ratios obtained were also compared with those determined by thermal ionization mass spectrometry (TIMS). An agreement
of about 1% was obtained in the 241Am/243Am ratios determined by the two methods and also by using the two algorithms for α-spectrum evaluation. 相似文献
11.
A. V. Il’yasov N. K. Gaisin B. I. Buzykin R. B. Zaripov 《Russian Chemical Bulletin》2010,59(8):1506-1511
The 1H spin-lattice relaxation times of the proton-bearing groups and the 31P spin-lattice relaxation times in C-phosphorylated oximes R1C(=NOH)P(=O)R2R3 (R1 = Ph, R2 = R3 = OMe; R1 = Ph, R2 = OMe, R3 = OCH2CH2Br; R1 = PhCH2, R2 = R3 = OCHMe2) and dioxime R2P(=O)C(=NOH)(CH2)4C(=NOH)P(=O)R2 (R = OMe) in DMSO-d6 were measured. The characteristic reorientation times of the whole molecules were estimated using the measured values of
the 1H relaxation times and the results of semiempirical PM3 quantum chemical calculations of the molecular geometries. The reorientation
times were used to identify the contributions of different relaxation mechanisms to the rate of 31P spin-lattice relaxation. The anisotropy of the chemical shielding of 31P nuclei was evaluated from the difference between the 31P relaxation rates measured at 101.27 and 161.92 MHz. 相似文献
12.
Árpád Bihari Zoltán Szűcs Magdolna Mogyorósi Tamás Pintér 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(3):759-763
The low- and intermediate-activity level liquid wastes produced by the Paks Nuclear Power Plant (NPP) contain routinely measureable
gamma-emitting (e.g., 54Mn, 60Co, 110mAg, and 137Cs) as well as many so-called “difficult-to-measure” radionuclides. Despite of their low specific activity compared to the
total, the reliable determination of these radionuclides is an important issue of nuclear waste management. The increasing
amount of waste samples to be qualified yearly by our laboratory put a pressure on revising the existing procedure of 99Tc separation applied. We have managed to halve the initial amount of the sample required to achieve the same level of detection
of technetium. Furthermore, one of the new purifying steps introduced have proved to be able to separate 108mAg (and 110mAg) better than 99% keeping the 99Tc content of the product almost intact. Means of separation of 99Tc from 106Ru and 124+125Sb have also been successfully investigated. As intended, this new procedure has a major impact on the chemical reagent as
well as the electricity requirement of the separation making it more cost-effective. 相似文献
13.
Claudia Landstetter Christian Katzlberger 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(2):467-471
Screening measurements for 3H, 226Ra, 222Rn and 238U in ground water were performed within a ground- and drinking water project in Austria. The aim of this project is to get
an overview of the distribution of natural radionuclide activity concentration levels in ground water bodies. In some cases
this water is used for drinking water abstraction. In this paper methods and results of the screening measurements are presented.
Regions with high activity concentrations were identified and in these regions further investigation for 228Ra, 210Pb and 210Po will be conducted. 相似文献
14.
Mahdi Sadeghi Milad Enferadi Hojjat Nadi Claudio Tenreiro 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(1):141-144
Amongst the various radioisotopes of molybdenum, 93mMo in its no-carrier added form might be a potential candidate radionuclide in the field of nuclear medicine due to its suitable
half-life (T
1/2 = 6.85 h) and for its intense gamma line at 263.14 keV. Aim of the presented study is to compare the calculated cross sections
for the production of 93mMo incident proton energy up to 30 MeV, theoretical calculation of production yield and calculation of target thickness requirement.
Also, deposition of 93NbO2 on Cu substrate was carried out via two special sedimentation methods for the production of 93mMo and a simple and selective extraction of molybdenum was described. 相似文献
15.
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
16.
L. Popov G. Mihailova I. Naidenov 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(2):223-237
The origins of different artificial radionuclides found in soils from Northern and Southern Bulgaria was determined by measurements
of their actual concentrations and respective ratios. On the basis of the measured mobility and concentrations of the investigated
radionuclides in soils, it was estimated that after the Chernobyl accident the mean depositions of fresh 137Cs were 3.0 ± 2.5 kBq/m2 for Northern Bulgaria and 15 ± 7 kBq/m2 for Southern Bulgaria. As a result of global fallout following atmospheric nuclear weapon tests in the 1950s, mean depositions
(corrected to 1965) were calculated for Northern and Southern Bulgaria as follows: for 90Sr—1.0 ± 0.5 and 2.3 ± 1.3 kBq/m2, 238Pu—1.3 ± 0.8 and 2.8 ± 1.6 Bq/m2, 239+240Pu—15 ± 14 and 47 ± 38 Bq/m2, and 241Pu—520 ± 200 and 760 ± 260 Bq/m2. 相似文献
17.
Composite material PAN-DMG, containing chelating agent dimethylglyoxime (DMG) immobilized in porous matrix of binding polymer
polyacrylonitrile (PAN), was used for nickel separation and concentration. Method for preparation of 59Ni source for low energy photon spectrometry was developed using homogeneous precipitation of nickel with DMG. The proposed
method was tested with two types of real radioactive waste (boric acid concentrate from nuclear power plant (NPP) evaporator
and spent ion exchanger from NPP). 相似文献
18.
S. Watanabe N. S. Ishioka T. Sekine H. Kudo H. Shimomura H. Muramatsu T. Kume 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(3):499-502
Summary Hydrophilic endohedral 133Xe-fullerenols, [133Xe@C60(OH)xand 133Xe@C70(OH)x], were synthesized from hydrophobic endohedral 133Xe-fullerenes. The yield of endohedral 133Xe-fullerenols extracted in water was about 40% and 23% for C60and C70, respectively. The products stored in 0.9% NaCl solution at 20 °C were stable enough to be used in nuclear medicine. 相似文献
19.
Donald E. Dry Warren J. OldhamJr. Scott M. Bowen 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(2):635-640
The long-lived rare earth isotopes 151Sm (90 years, β
max = 76.3 keV) and 147Pm (2.62 years, β
max = 224.6 keV) are low-yield fission products that generally require lengthy separation procedures to isolate and count by
their beta emissions. We will describe novel liquid scintillation counting techniques using radioactive tracers to determine
radiochemical yields from an environmental matrix. The recovery of 151Sm is determined from the alpha decay (2.25 MeV) of 147Sm in the natural Sm carrier and is in excellent agreement with the gravimetric recovery. The 147Pm recovery is determined by the use of 145Pm (17.7 years, EC) tracer, custom-produced at LANL using an isotopically enriched target of 144Sm. We have determined the 145Pm recovery both from the 37.4 keV kα1 X-ray, and the electron-capture emissions by LSC. A comparison of these recovery methods is presented. 相似文献
20.
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