共查询到20条相似文献,搜索用时 31 毫秒
1.
N. Matsuoka N. Momoshima T. Okai Y. Takashima N. Shiraishi 《Journal of Radioanalytical and Nuclear Chemistry》1988,120(1):21-27
A simple and portable apparatus was developed for measurements of85Kr and133Xe that would be released into the atmosphere in an emergency situation of nuclear facilities. The method is based on cryogenic adsorption of these gases on charcoal followed by chromatographic separation from other gases. The85Kr and133Xe recovered from atmospheric air are determined separately by liquid scintillation counting. It takes about 1 hour for the stepwise determination of85Kr and133Xe. The atmospheric concentration of 3·10–3 Ci per m3 air (1.1·102 Bq/m3 air) is measurable for both nuclides with 20% counting error. 相似文献
2.
P. K. Kuroda 《Journal of Radioanalytical and Nuclear Chemistry》1990,142(1):113-118
The isotopic compositions of xenon released from the Oklo reactor at temperatures below 1000°C are such that the abundances of131Xe,132Xe and134Xe relative to136Xe are markedly enhanced when compared to the relative fission yields from the thermal neutron-induced fission of235U. These anomalies can be attributed to the fact that131Xe,132Xe and134Xe have fairly long-lived precursors: 8.04-day131I, 78.2-hour132Te and 42-minute134Te, respectively. It is possible to determine the duration of the time when the reactor was turned off from the ratios of excess132Xe to excess134Xe in these anomalous xenon fractions released from the Oklo reactor. Calculations based on the available xenon isotope data that the time period during which the reactor was turned off was approximately 2 to 3 hours. 相似文献
3.
Y. Jao W. L. Cheng H. J. Chen C. C. Shaeh C. C. Huang Y. M. Lin 《Journal of Radioanalytical and Nuclear Chemistry》1995,194(2):411-417
This study was performed under the joint TRMC/INER program for the determination of low level85Kr and133Xe concentrations in the environmental air samples. Based on cryogenic adsorption of krypton and xenon on charcoal followed by chromatographic separation from other gases, the85Kr and133Xe recovered from 200 liters of atmospheric air can be determined by either on-line gas flow proportional counter or liquid scintillation counting. The recovery yields of krypton and xenon examined by using85Kr and133Xe tracers were nearly 100%. The minimum detectable activity of85Kr and133Xe by gas flow proportional counting is about 7.40 Bq. The method is satisfactory for environmental monitoring applications under abnormal conditions of nuclear facilities. However, for lower level environmental85Kr and133Xe measurements, the liquid scintillation counting method can be applied due to their extremely low detection limits (i.e. 0.107 Bq and 0.093 Bq for85Kr and133Xe, respectively). Using this method, the measurable limits of concentrations are 0.535 Bq/m3 and 0.466 Bq/m3 for85Kr and133Xe, respectively. 相似文献
4.
R. Münze O. Hladik S. A. Marei S. El-Bayoumy M. El-Garhy 《Journal of Radioanalytical and Nuclear Chemistry》1978,45(1):45-54
The fractional release of133Xe at different temperatures was studied as a function of time in the presence of an atmosphere of air during post-irradiation
annealing of uranium metal. It was found that the relation between the fractional release and t1/2 is irregular. There is an initial step in the annealing curves (at the temperature range of 400–710°C) which decreases by
increasing temperature and totally disappears at the high temperature of 800–1000 °C. The other parts of the release curves
are typical for133Xe release from uranium metal. The initial step was found to be due to the surface oxidation of uranium metal. 相似文献
5.
P. L. Reeder T. W. Bowyer J. I. McIntyre W. K. Pitts 《Journal of Radioanalytical and Nuclear Chemistry》2001,248(3):617-622
The International Monitoring System for the Comprehensive Nuclear-Test-Ban Treaty will include measurements of Xe fission products. Pacific Northwest National Laboratory has developed an automated system for separating Xe from air which detects Xe fission products using a beta-gamma counting system for 131mXe, 133mXe, 133gXe, and 135gXe. Betas and conversion electrons are detected in a plastic scintillation cell containing the Xe sample. Gamma and X-rays are detected in a NaI(Tl) scintillation detector which surrounds the plastic scintillator sample cell. Two-dimensional pulse-height spectra of gamma-energy versus beta-energy are obtained. The plastic scintillator spectrum in coincidence with the 31-keV X-rays from 131mXe. 133mXe, and 133gXe is a complex mixture of conversion electrons and betas. A new technique to simultaneously measure the delayed coincidence (T
1/2 = 6.27 ns) between beta-particles from 133gXe and conversion electrons depopulating the 81-keV state in 133 Cs is being developed. This technique allows separation of the 133gXe beta spectrum from the conversion electrons due to 131mXe and 133mXe and uniquely quantifies all three nuclides. 相似文献
6.
Weihua Zhang Pawel Mekarski Jonathan Lam Kurt Ungar Eric Pellerin 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(3):475-482
In this work, a Monte Carlo (MC) simulation model is established to accurately characterize a phoswich beta-gamma coincidence detector system. This model can be easily used to predict the beta-gamma coincidence efficiencies of xenon radioisotopes at various stable xenon concentrations in the counting cell. The results demonstrate that there is a significant inverse correlation between beta-gamma coincidence efficiency and stable xenon concentration. The influence of stable xenon concentration on beta-gamma coincidence counting efficiency has been investigated for each individual xenon radioisotope. The results indicate that the effect of stable xenon concentration on beta-gamma coincidence efficiency depends on the xenon radioisotope and its decay modes. The coincidence efficiency of 133Xe with 31.0-keV X-ray decay mode is the most affected one; and then followed by 131mXe, 133Xe with 81.0-keV gamma-ray decay mode, 133mXe and finally 135Xe. The study also indicates that the gamma absorption by xenon gas plays more of a role in the decrease of beta-gamma coincidence efficiency for 133Xe and 135Xe, and that the conversion electron spectrum shifting and broadening plays more of a role in the reduction of beta-gamma coincidence efficiency for the metastable radioxenon of 131mXe and 133mXe. 相似文献
7.
S. Watanabe N. S. Ishioka T. Sekine A. Osa M. Koizumi H. Shimomura K. Yoshikawa H. Muramatsu 《Journal of Radioanalytical and Nuclear Chemistry》2003,255(3):495-498
Ion implantation was applied to the production of endohedral 133Xe-fullerene. Using an isotope separator, 133Xe ions were implanted into a fullerene target of C60 and C70 produced by vacuum evaporation on a Ni backing. An HPLC analysis following dissolution of the fullerene targets in o-dichlorobenzene corroborated the formation of 133Xe@C60 and 133Xe@C70, showing a strong correlation between C60/C70 and 133Xe. The observed tailing following 133Xe peaks in the elution curves suggests a possibility of the isolation of endohedral 133Xe-fullerene from empty fullerene. 相似文献
8.
M. Tabasi M. Ghannadi-Maragheh l M. Shamsaii A. R. Khanchi 《Journal of Radioanalytical and Nuclear Chemistry》2005,264(3):679-686
Summary Separation and purification of 133Xe from acidic solution containing uranium, 99Mo and 131I has been developed. In the first step of this work, uranium pellets were dissolved under pressure (8-15 bar) in 8M nitric acid solution. Then133 Xe and other gases were conducted to activated charcoal cold trap. Final purification of 133Xe from impurities such as NOx, radioiodine and krypton was performed by passing through a molecular sieve preparative chromatographic column using helium as mobile phase. The final recovery of 133Xe from the separation-purification process was higher than 98%. Adsorption-desorption behavior of radioxenon on the charcoal and molecular sieves have also been studied and discussed. 相似文献
9.
Applications of gas chromatography and gamma spectrometry to fission gas measurements 总被引:1,自引:0,他引:1
A gas sampler with lead shield has been designed for transferring the grab gas sample taken from the sampling station of Taiwan nuclear power reactor. The methods involving gas chromatography and gamma spectrometry have been developed for the determination of fission gases. A gas chromatograph equipped with TCD was used for measurement of gas composition. Column requirements are identified and optimum operating conditions are discussed. A single analysis is completed within 25 minutes for all of the gas constitutents and 12 minutes for only Xe and Kr. The detection limit is 0.005 mm partial pressure for Kr and Xe and a precision of ±1% relative is achieved for all the sample constituents. Combined error determinations for the method denote an attainable accuracy of less than ±2% for constituents at a sample pressure above 10 mm. Mixing and dispensing of the radioactive gases were carried out in a special gas mixing line. In experiment, calibration factors for measurement of133Xe and85Kr in ampules are determined in an isotope calibrator and by Ge(Li) gamma ray spectrometry. The relative precisions of 0.14% and 0.5% are readily achieved for85Kr and133Xe, respectively. The calibration uncertainty in85Kr measurement is 0.4%. 相似文献
10.
D. A. Haas S. R. Biegalski K. M. Foltz Biegalski 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):677-680
The Spectral Deconvolution Analysis Tool (SDAT) software was developed to improve counting statistics and detection limits for nuclear explosion radionuclide measurements. SDAT utilizes spectral deconvolution spectroscopy techniques and can analyze both β–γ coincidence spectra for radioxenon isotopes and high-resolution HPGe spectra from aerosol monitors. The deconvolution algorithm of the SDAT requires a library of β–γ coincidence spectra of individual radioxenon isotopes to determine isotopic ratios in a sample. In order to get experimentally produced spectra of the individual isotopes, we have irradiated enriched samples of 130Xe, 132Xe, and 134Xe gas with a neutron beam from the TRIGA reactor at The University of Texas. The samples were counted in an Automated Radioxenon Sampler/Analyzer (ARSA) style β–γ coincidence detector. The spectra produced show that this method of radioxenon production yields samples with very high purity of the individual isotopes for 131mXe and 135Xe and a sample with a substantial 133mXe to 133Xe ratio. 相似文献
11.
12.
Martin E. Keillor Matthew W. Cooper James C. Hayes Justin I. McIntyre 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):699-702
Pacific Northwest National Laboratory uses beta-gamma coincidence detectors in a number of xenon sampling and measurement
systems to enable simultaneous, sensitive measurements of 131Xe, 133Xe, 133mXe, and 135Xe for treaty monitoring applications. In recent years, a new style of beta–gamma detector was developed to improve upon the
detector module used in the Automated Radioxenon Sampler/Analyzer. The results of an MCNP5 Monte Carlo simulation of the new
detector cell are presented, with particular emphasis on the identification of an energy deposition sequence with the potential
to introduce significant error into the detector efficiency calibration. This sequence occurs when an 81 keV gamma from 133Xe is absorbed in an inactive region of the CsI(Na) scintillator, followed by emission of a 31 keV X-ray from cesium (or possibly
a 28.5 keV X-ray from iodine). These X-rays add excess counts into the 31 keV peak observed in the decay of 133Xe. The impact of this effect on different efficiency calibration techniques is discussed. 相似文献
13.
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
14.
K. Sakamoto Y. Hamajima S. Yamaguchi T. Takashima K. Itoh 《Journal of Radioanalytical and Nuclear Chemistry》1980,60(2):411-422
Samples of an andesite (Asama-yama, Japan) and a basalt (Kilauea, Hawaii) were finely fractioned by density and the U distributions
among the separates were determined by homogenized fission track method. Groundmass was found to be enriched with U; one half
of the andesite U and almost all of the basalt U are accounted for by the groundmass U. Cerium and other REE are correlated
with U. In the andesite separates Na is accompanied by these elements, but Fe and Co are rather anticorrelated. Uranium concentrations
in the bulk samples and some of the separates were then compared with those determined by133Xe extracted by heating at 1600°C. Fissiogenic133Xe seems to become labile in groundmass, especially of the andesite, during reactor irradiations for 5 h or more. Stepwise
heating experiments suggested that133Xe in U-rich groundmass tends to escape at low temperatures and the remaining133Xe is mostly retained in highly refractory sites in phenocryst rather poor in U. 相似文献
15.
Troy A. Robinson Nick R. Mann Christopher P. Oertel Matthew G. Watrous Christopher A. McGrath John P. Peterson 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(3):1681-1686
Quantification of low-activity noble gases in air is typically accomplished through separation of the noble gas from air followed by radiometric assay. This work is aimed at quantification of radioactive noble gas in air without extraction. A high pressure aluminum Marinelli counting vessel was designed and fabricated that can be placed on a coaxial high purity germanium detector for gamma counting. Characterization of the performance of this Marinelli using MCNP modeling, large excesses of activity, and low-activity noble gas in air is discussed. Minimum detectable concentrations achieved during a 24 h count are: 5, 10, 50, and 1 Bq/m3 for 133Xe, 133mXe, 131mXe, and 135Xe, respectively. 相似文献
16.
W. Zhang K. Ungar I. Hoffman R. Lawrie 《Journal of Radioanalytical and Nuclear Chemistry》2009,280(1):121-128
To support interpretation of observed atmospheric 135Xe, 133Xe, 133mXe and 131mXe, a database of xenon radioisotope in the primary coolant of CANDU reactors has been established. This database is comprised
of 40000 records of high-quality xenon radioisotope analyses. Records from the database were retrieved by a specifically designed
data-mining module and subjected to further analysis. Results from the analysis were subsequently used to study isotopic ratios
of observed xenon radioisotopes in the CANDU reactor primary coolant. These studies provided novel and practical information
on the characterization of CANDU reactor xenon radioisotope releases, which can be used to discriminate between reactor effluence
and underground nuclear test releases. 相似文献
17.
S. Biegalski A. Flory D. Haas J. Ely M. Cooper 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(1):471-476
The standard deconvolution analysis tool (SDAT) was developed for analysis of radioxenon β–γ coincidence spectra measured as part of the international monitoring system as defined in the comprehensive nuclear-test-ban treaty. The SDAT software analyzes each β–γ coincidence spectrum by fitting library vectors of each radionuclide of interest: 131mXe, 133mXe, 133Xe, and 135Xe. Detector background and radon are incorporated as optional components of the sample solution. Results are reported in mBq m?3. A new graphical user interface has been developed to facilitate ease of use and improve the data visualization. Automated energy versus channel calibration algorithms were developed and implemented based on 137Cs β–γ coincidence spectra. Details on the user tool and testing are included. 相似文献
18.
Alain Vivier Gilbert Le Petit Benoit Pigeon Xavier Blanchard 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):743-748
When a net count value is below the type 1 error critical limit it is customary to declare that the activity is “below the
detection limit”. The content of this declaration is particularly impoverished, incapable for example of discriminating between
a net measurement just below the critical limit, but positive, and a negative net measurement, two types of information that
it is legitimate and intuitive to think do not have the same weight of information. In the case of a spectral measurement
of 131mXe and 133mXe certain information is available according to the various X and gamma emissions, which might all be below their respective
critical limits. We shall see that a Bayesian probabilistic approach can be used, without considering the critical limits,
to obtain anti-correlated maximum likelihood values taking all the information into account jointly and to obtain powerful
and pertinent information in the form of the absolute probability that the sample contains 131mXe and/or 133mXe, all possible activity values combined. Conversely, of course, this is used immediately to deduce the probability that
the sample does not contain 131mXe and/or 133mXe. This information enables the customary critical limit to be ignored. 相似文献
19.
Georg Steinhauser Michael Lechermann Anders Axelsson Helmuth Böck Anders Ringbom Paul R. J. Saey Clemens Schlosser Mario Villa 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(1):169-174
Radioxenon emissions of the TRIGA Mark II research reactor in Vienna were investigated with respect to a possible impact on the verification of the Comprehensive Nuclear Test-Ban-Treaty. Using the Swedish Automatic Unit for Noble Gas Acquisition (SAUNA II), five radioxenon isotopes 125Xe, 131mXe, 133mXe, 133Xe and 135Xe were detected, of which 125Xe is solely produced by neutron capture in stable atmospheric 124Xe and hence acts as an indicator for neutron activation processes. The other nuclides are produced in both fission and neutron capture reactions. The detected activity concentrations ranged from 0.0010 to 190 Bq/m³. The source of the radioxenon is not yet fully clarified, but it could be micro-cracks in the fuel cladding, fission of 235U contaminations on the outside of the fuel elements or neutron activation of atmospheric Xe. Neutron deficient 125Xe with its highly complex decay scheme was seen for the first time in a SAUNA system. In many experiments the activity ratios of the radioxenon nuclides carry the signature of nuclear explosions, if 131mXe is omitted. Only if 131mXe is included into the calculations of the isotopic activity ratios, the majority of the measurements revealed a “civil” signature (typical for a NPP). A significant contribution of the TRIGA Vienna to the global or European radioxenon inventory can be excluded. Due to the very low activities, the emissions are far below any concern for human health. 相似文献
20.
K. Sakamoto K. Itoh T. Takashima S. Yokoyama K. Yamazaki 《Journal of Radioanalytical and Nuclear Chemistry》1980,60(2):323-342
Uranium concentrations in three types of inclusions of the Allende (C III), a bulk sample of the Plainview (H5), and a bulk
and 5 to 15 density separates of the Huckitta pallasite were determined and discussed by comparing the results from homogenized
fission track and/or239Np analyses with the133Xe results. Stepwise heating experiment revealed that the133Xe release from the Plainview is bimordal and incomplete by a simple heating at 1600 °C, and that the133Xe releases in the Huckitta bulk and metallic samples are multitudinous but can be extracted rather completely at 1600–1700
°C. In the Huckitta, uranium-rich phase (∼100 ppb) was in the lightest density fraction of d=2.9–3.3, but the bulk uranium
was found to be mostly from the heavy metal-rich fraction of d>4.2. 相似文献