共查询到20条相似文献,搜索用时 339 毫秒
1.
N. M. Antovic V. Popovic I. Antovic N. Svrkota P. Vukotic 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(1):81-88
A coincidence method for measuring 137Cs, 40K, 226Ra and 232Th decay products activity in soil, vegetation and fish samples, was applied to the six-crystal gamma-coincidence spectrometer
PRIPYAT-2M. In this way, some problems appeared in simultaneous measurement of 137Cs, 226Ra and 232Th by NaI(Tl) detectors and the PRIPYAT-2M spectrometer were solved. The obtained results were agreeable with the HPGe spectrometer
ones. 相似文献
2.
<Superscript>226</Superscript>Ra and <Superscript>228</Superscript>Ra determination in environmental samples by alpha-particle spectrometry 总被引:1,自引:1,他引:0
J. L. Aguado J. P. Bolivar R. García-Tenorio 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(1):191-199
A complete methodology for 226Ra and 228Ra determination by alpha-particle spectrometry in environmental samples is being applied in our laboratory using 225Ra as an isotopic tracer. This methodology can be considered highly suitable for the determination of these nuclides when
very low absolute limits of detection need to be achieved. The 226Ra determination can be performed at any time after the isolation of the radium isotopes from the analyzed samples while the
228Ra determination needs to be carried out at least six months later through the measurement of one of its grand-daughters.
The method has been validated by its application to samples with known concentrations of these Ra nuclides, and by comparison
with other radiometric methods. 相似文献
3.
N. E. Bores M. K. Schultz J. M. Rankin A. J. Denton G. F. Payne 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):985-990
The Intercomparison Studies Program (ISP) at the Oak Ridge National Laboratory (ORNL, Oak Ridge, TN USA) provides natural-matrix
human urine quality-assurance/quality-control (QA/QC) samples to radiobioassay analysis laboratories. Samples are provided
to these laboratories as “single-blind” or “double-blind” unknowns, spiked with radioactive-solution standards at “low” levels
(e.g., 0.7–7 Bq g−1 for 3H and 0.7–7 Bq kg−1 for 90Sr). Participants use the results as a tool for self-evaluation and a measure of performance. In this paper, sample preparation
and the results of testing during the years 2001–2005 for 3H and 90Sr are presented and discussed. 相似文献
4.
Szabolcs Osváth Nóra Vajda Zsuzsa Molnár Éva Kovács-Széles Mihály Braun Máté Halász 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(1):31-38
A radioanalytical method (based on separation using UTEVA columns and ICP-MS measurement) has been used for determination of 93Zr in 37 nuclear power plant samples. As 93Nb might affect the detection of 93Zr, Monte Carlo activation model was used to calculate the expected 93Zr/natZr mass ratio, which was compared to measured ones. It was found, that a decontamination factor of 103 is sufficient to get a measurement uncertainty of less than 10%. 相似文献
5.
Methodologies for the quantification of measurement uncertainties associated with the determination of 210Pb- and 210Po-specific activities by liquid scintillation counting (LSC) and alpha-particle spectrometry are presented, and are demonstrated
using the soil reference material IAEA-326. Major contributors to the combined uncertainty associated with the measurement
result of 210Pb were the uncertainties of net count rates in the 210Pb energy region of the sample spectrum and in the 210Bi energy region of the blank spectrum. The predominant sources of uncertainty in the measurement of 210Po were the uncertainties of net count rates in the regions of interest of 209Po and 210Po. The relative standard uncertainty of 210Po exponentially increases with the time interval between the sampling date and the separation date of Po, and this effect
is strongly dependent on the 210Po/210Pb activity ratio. When the specific activity of 210Pb is much higher than that of 210Po in the sample, the relative standard uncertainty of the 210Po determination increases significantly within a short time interval between the sampling date (or reference date) and the
separation date of Po in samples. 相似文献
6.
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
7.
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
8.
Tongke Zhao Lei Zhang Qiuju Guo Wenbin Dong 《Journal of Radioanalytical and Nuclear Chemistry》2017,313(2):379-384
The activity concentrations of 218Po, 214Pb and 214Bi [i.e. C(218Po), C(214Pb), and C(214Bi)] and the calculated concentration ratios [i.e. 1:C(214Pb)/C(218Po):C(214Bi)/C(218Po)] are necessary for assessing radon and its progenies exposure. In this study, a measurement method of radon progenies concentrations with both high sensitivity and low uncertainty, was developed based on the Kerr method. The field measurement results of radon progeny concentrations and calculated concentration ratios in both typical indoor and outdoor environments in Beijing, China, were reported. The effects of air exchange rate on concentration ratios of radon progenies in indoor environments were discussed. 相似文献
9.
M. Liezers O. T. FarmerIII M. L. Thomas 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(1):309-313
The measurement of fission product cesium isotopes 135Cs and 137Cs at low femtogram (fg) 10−15 levels in ground water by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) is reported. To eliminate the natural barium
isobaric interference on the cesium isotopes, in-line chromatographic separation of the cesium from barium was performed followed
by high sensitivity ICP-MS analysis. A high efficiency desolvating nebulizer system was employed to maximize ICP-MS sensitivity
~10 cps/fg. The three sigma detection limit for 135Cs was 2 fg/mL (0.1 μBq/mL) and for 137Cs 0.9 fg/mL (0.0027 Bq/mL) measured from the standard with analysis time of less than 30 min/sample. Cesium detection and
135/137 isotope ratio measurement at very low femtogram levels using this method in a spiked ground water matrix is also demonstrated. 相似文献
10.
Dimitrios C. Xarchoulakos Konstantina Kehagia Nikolaos Kallithrakas-Kontos Constantinos Potiriadis 《Journal of Radioanalytical and Nuclear Chemistry》2017,312(2):285-292
For the first time, a radiological study for the dissolved 238U, 234U, 210Pb and 210Po was held in major Greek rivers across the country. 234U/238U activity ratios are above one in all samples and 210Po/210Pb activity ratios are respectively below the unit indicating the disequilibrium in the samples. Quite satisfactory correlations were observed among 234U and 238U as well as among 210Po and 210Pb values. Uranium isotopes were separated by ion exchange and electroplated on stainless steel plates. 210Po was spontaneously deposited on nickel plates, while 210Pb was indirectly determined through the ingrowth of 210Po. The sources were measured by a-spectrometry. 相似文献
11.
Activity concentrations of 238U, 235U and 234U were determined in different sources of drinking water at the Obuasi gold mines and its surrounding areas in Ghana. Water
samples collected from the mines and its surrounding areas were analyzed using direct gamma-ray spectrometry and neutron activation
analysis. The 234U/238U and 235U/238U ratios were calculated and the mean values range from 1.27 to 1.38 and from 0.044 to 0.045 respectively. The average 234U/238U ratio was from 1.27 for groundwater to 1.38 for treated water, demonstrating the lack of equilibrium. The average 235U/238U activity ratio is 0.045, indicating that only natural uranium was detected in the samples investigated. 相似文献
12.
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
13.
Studies of 137Cs distribution in East Malaysia were carried out as part of a marine coastal environment project. The results of measurements
will serve as baseline data and background reference level for Malaysia coastline. Twenty-one locations were identified along
the coastline of East Malaysia, and from each location water samples were collected at the surface of the seawater. Ten near-shore
locations were also selected and seawater was collected at three different depths. Large volumes of seawater were collected
and the co-precipitation technique was employed to concentrate cesium. A known amount of 134Cs tracer was added as yield determinant, followed by addition of copper(II) nitrate salt and a solution of potassium hexacyanoferrate(II)
trihydrate, to precipitate the total cesium. The precipitate slurry was oven dried at 60 °C for 1–2 days, finely ground and
counted using gamma-ray spectrometry. The activity of 137Cs was determined by measuring the peak area under the photopeak of the gamma-spectrum at 661 keV, which is equivalent to
gamma-intensity corrected for detection efficiency, percentage of gamma-ray abundance of the radionuclide and recovery of
134Cs tracer. There were no significant differences of 137Cs activities both in surface and bottom water samples at 95% confidence level. The activity of 137Cs (for all samples) was found to be in the range of 1.47 to 3.36 Bq/m3 and 1.69 to 3.32 Bq/m3 for Sabah and Sarawak, respectively. 相似文献
14.
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
15.
Z. Y. Chen F. Xie X. H. Wang Y. F. Chang Z. B. Zhang 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(1):257-261
A method of efficiency calibration for the measurement of 88Kr and 138Xe by HPGe γ-spectrometer is proposed in the present paper. The question for the efficient calibration is, how to achieve
homogeneous sources of 88Kr-88Rb and 138Xe-138Cs. The fission product gases were obtained by irradiating a precisely measured amount of U3O8 (90% 235U) filled in a quartz glass ampoule. Source cell was first filled up with stearic acid, and then the fission product gases
were charged into it. Xenon and krypton are not adsorbed on stearic acid, therefore, homogeneous sources of 88Kr-88Rb and 138Xe-138Cs can be prepared. The results of the experiment demonstrate that the method is feasible and successful. 相似文献
16.
M. Yamamoto A. Sakaguchi J. Tomita T. Imanaka K. Shiraishi 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(1):93-103
To estimate the dietary intakes of 210Pb and 210Po for the Japanese adults and their annual effective doses, 210Pb and 210Po were measured for 240 daily diet samples collected at two locations of Ishikawa Prefecture in Japan over three years by
duplicate portion studies. No appreciable differences in intake rates of 210Pb and 210Po and their 210Po/210Pb ratios were seen among the years in each district, and between the two districts. The intake rates evaluated using 240
diet samples were 0.20 Bq/d/p for 210Pb and 0.61 Bq/d/p for 210Po as a median, respectively. Annual effective doses of 210Pb and 210Po for Japanese adults were estimated to be 0.050 and 0.053 mSv/y, respectively. 相似文献
17.
K. M. Rajashekara Y. Narayana K. Siddappa 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(2):379-388
The concentrations of 210Po and 210Pb have been measured in soil, sediment and rock samples collected from major rivers of coastal Karnataka, viz. Kali, Sharavathi
and Netravathi. The activity of 210Po and 210Pb in the samples were separated by radiochemical methods and the activity was counted using ZnS(Ag) alpha-counter. The activity
ratio of 210Po and 210Pb and the dependence of organic matter content on the activity of these radionuclides were studied. 相似文献
18.
H. Michel M. E. Ketterer G. Barci-Funel 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(2):485-490
Plutonium isotopes were measured by alpha-spectrometry and ICP-MS in sediment samples from two European lakes: Blelham Tarn
in U.K. and Stechlin lake in Germany. The ICP-MS measurements were made after alpha-spectrometry counting of the planchets.
The planchets were prepared by traditional electrodeposition method after radiochemical extraction, separation and purification
of the Pu fraction. A short radiochemical separation using plutonium selective resin, between the two spectrometry measures,
is presented. The results show that these two complementary methods are in good agreement, the plutonium activity concentrations
are the same. Alpha-spectrometry allows the 238Pu determination and ICP-MS individual measurement of 239Pu and 240Pu. 238Pu/239+240Pu and 240Pu/239Pu ratios are calculated to determine the plutonium contamination source. With the results of these two techniques, it could
be demonstrate that the plutonium is of global fallout origin. 相似文献
19.
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
20.
Marin Ayranov Dorothea Schumann 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(3):649-654
The station for pions cancer therapy was operated at PSI from 1980 to 1992. After a cooling time of 12 years it’s made of
copper beam dump was cut and samples were taken for analytical purposes. The sampling collected about 500 g of high active
copper chips that can be used for separation of exotic radionuclides. The analyses by gamma spectrometry, LSC and AMS showed
main nuclides present to be 60Co, 54Mn, 22Na, 65Zn, 26Al, 53Mn, 59Ni, 63Ni, 55Fe and 60Fe and 44Ti with a daughter nuclide 44Sc. In the frame of ERAWAST project a procedure combining selective precipitation and ion exchange for the separation of the
rare radionuclides from the copper beam dump was developed. The proposed separation procedure is easy for remote controlled
implementation in a hot cell. The ion exchange separation of Ni, Al, Mg, Ti and Fe was complete and high decontamination factors
for copper and cobalt were achieved. Based on the developed procedure a remotely controlled system for separation of exotic
radionuclides from the copper chips was set up. The full scale system was installed in a hot cell where high activity levels
can be handled. In order to evaluate the reliability and functionality of the system extensive tests have been done. During
the test period 13.86 g in total of the proton irradiated copper beam dump were processed for separation of 26Al, 59Ni, 53Mn, 44Ti and 60Fe. The results showed that the system was operational and the radionuclide separation was selective with high chemical yield.
The procedure manages as well the generated liquid wastes containing high level of 60Co activity. 相似文献