Environmental liquid scintillation analysis
01 Jan 2020-pp 41-136
TL;DR: In this article, the authors present the principles of liquid scintillation counting (LSC) measurement techniques and focus on the practical issues in the LSC determination of environmental radionuclides, as well as the status of the present research progress in these aspects.
Abstract: Liquid scintillation counting (LSC) is a major method for the measurement of beta-emitting and some alpha-emitters. It has been applied in many aspects such as the monitoring of environmental radioactivity, the behavior of radionuclides in the environment, and the characterization of nuclear waste for the decommissioning of nuclear facilities. Radionuclides are also widely applied to the investigation of environmental processes. However, the level of radionuclides in the environment is normally very low, and the resolution of LSC alone is not sufficiently high to identify and quantitatively measure different radionuclides. Low background LSC and chemical separation and purification are needed. This chapter aims to present the principles of LSC measurement techniques for the above purposes and focus on the practical issues in the LSC determination of environmental radionuclides, as well as the status of the present research progress in these aspects. The principles of low-level counting using LSC including the methods for reducing the background in the LSC instrument and practical issues in sample preparation are presented. The principles and applications for the measurement of alpha-emitters using LSC with the alpha/beta discrimination features are presented. The main application of triple-to-double coincidence ratio–based LSC in normal and Cerenkov counting models are also described. Most of the effort of this chapter focuses on the application of LSC in the determination of different anthropogenic and naturally occurring radionuclides, including tritium, 14C, 55Fe, 63Ni, 89,90Sr, 90Y, 99Tc, 241Pu, 36Cl, 41Ca, 129I, 210Po, 210Pb, isotopes of uranium, thorium, radium, and radon. Besides the LSC measurement methods, the detailed and practical chemical separation of these radionuclides from different sample matrices, as well as the sample preparation methods for LSC measurement are discussed based on the open publications and the experiences of the authors.
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01 Jan 1989
TL;DR: In this article, the authors developed a volatilization of the entire sample while simultaneously integrating the signal from each isotope, thus virtually eliminating the effects of isotope fractionation in the evaporation process.
Abstract: Techniques have been developed which permit rapid, high-precision analyses of uranium and plutonium by multiple-filament thermal ionization mass spectrometry utilizing a commercial multicollector instrument. The salient feature of the method is volatilization of the entire sample while simultaneously integrating the signal from each isotope, thus virtually eliminating the effects of isotope fractionation in the evaporation process. The method permits the analysis of samples much smaller than required for conventional techniques using Faraday collectors and is expected to have application in the analysis of many elements in addition to uranium and plutonium. Run-to-run reproducibilities of <0.02% (RSD) have been obtained for isotope ratios of uranium and plutonium. 7 refs., 5 figs., 4 tabs.
12 citations
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TL;DR: A comprehensive study to determine thorium, uranium and potassium elemental concentrations in surface soils throughout the accessible area of Cyprus using high-resolution gamma-ray spectrometry found the best-fitting relation was essentially of linear type with a correlation coefficient of 0.93.
Abstract: A comprehensive study was conducted to determine thorium, uranium and potassium elemental concentrations in surface soils throughout the accessible area of Cyprus using high-resolution gamma-ray spectrometry. A total of 115 soil samples was collected from all over the bedrock surface of the island based on the different lithological units of the study area. The soil samples were sieved through a fine mesh, sealed in 1000-mL plastic Marinelli beakers, and measured in the laboratory in terms of their gamma radioactivity for a counting time of 18 hours each. From the measured gamma-ray spectra, elemental concentrations were determined for thorium (range from 2.5x10^-3 to 9.8 micro g g-1), uranium (from 8.1x10^-4 to 3.2 micro g g-1) and potassium (from 1.3x10^-4 to 1.9 %). The Arithmetic mean values (A.M. +- S.D.) calculated are (1.2 +- 1.7) micro g g-1, (0.6 +- 0.7) micro g g-1, and (0.4 +- 0.3) %, for thorium, uranium and potassium, respectively, which are by a factor of three to six lower than the world average values of 7.4 micro g g-1 (Th), 2.8 micro g g-1 (U) and 1.3 % (K) derived from all data available worldwide. The best-fitting relation between the concentrations of Th and K versus U, and also of K versus Th, is essentially of linear type with a correlation coefficient of 0.93, 0.84, and 0.90, respectively. The Th/U, K/U, and K/Th ratios (slopes) calculated are equal to 2.0, 2.8x10^3,and 1.4x10^3, respectively.
9 citations
TL;DR: In this paper , the radiochemical analysis methods of low-level radionuclides 137Cs (Cesium) in environmental and biological samples are introduced and reviewed in detail, and the latest research progress is reviewed from the five aspects of sample pretreatment, determination, separation, calculation, application of radioactive cesium and the future is proposed.
Abstract: In the context of the rapid development of the world’s nuclear power industry, it is necessary to establish background data on radionuclides of different samples from different regions, and the premise of obtaining such basic data is to have a series of good sample processing and detection methods. The radiochemical analysis methods of low-level radionuclides 137Cs (Cesium) in environmental and biological samples are introduced and reviewed in detail. The latest research progress is reviewed from the five aspects of sample pretreatment, determination, separation, calculation, application of radioactive cesium and the future is proposed.
5 citations
TL;DR: A comprehensive review of the application of tracer testing technique to investigate porous media, mainly in O&G industry is presented in this article , in detail discussing the objectives, calculations, designing, injection, sampling, laboratory analysis and knowledge integration.
Abstract: Abstract The significance of the tracer testing technique is widely accepted in reservoir performance analysis in hydrology as well as in hydrocarbon exploration and production. The subsurface reservoir delineation for hydrocarbon exploration and optimum production is one of the most critical aspects of petroleum system analysis. The quality of the reservoir and its performance prediction require extensive knowledge of qualitative reservoir geology, its depositional environment, facies heterogeneity and engineering properties of subsurface formations. Tracer testing is amongst the few techniques available in the oil and gas (O&G) industry, which stands up to these expectations and is successfully used for quantitative determination and analysis of sub-seismic scale structural and stratigraphic heterogeneities. Tracer testing is also being utilized in determining residual oil saturation ( S or ) and lateral correlation of reservoir properties in the subsurface. Apart from the O&G industry, the concentration-based applications of tracer testing have been proved in hydrology, geothermal and medical science. A comprehensive review is presented to explain the application of tracer testing technique to investigate porous media, mainly in O&G industry. The type of tracers used, their selection criteria, concentration, and natural versus gradient and qualitative to a quantitative application are discussed in the current review. Generally, two types of tracers (chemical and radioactive) are preferred in the petroleum industry for gas/fluid flow assessment, waterflood optimization and establishing connectivity between multiple wells. The current paper reviews both types of tracer tests, namely single well and inter well, in detail discussing the objectives, calculations, designing, injection, sampling, laboratory analysis and knowledge integration. The preliminary aim was to provide a review of the tracer testing technique used in reservoir evaluation and well-to-well connectivity analysis.
3 citations
TL;DR: In this article, the authors explored the distribution of time intervals between signals from the photomultiplier tubes (PMTs) of a liquid scintillation counting (LSC) system when an ionizing particle is detected.
Abstract: This work explores the distribution of time intervals between signals from the photomultiplier tubes (PMTs) of a liquid scintillation counting (LSC) system when a scintillation burst caused by an ionizing particle is detected. This distribution is termed the cross-correlation distribution and it is shown that it contains information about the probability to detect a scintillation event. A theoretical model that describes the cross-correlation distribution is derived. The model can be used to estimate the mean number of detected photons in a LSC measurement, which allows the calculation of the detection efficiency. The theoretical findings are validated by Monte Carlo simulations and by experiments with low-energy beta-emitting and electron-capture radionuclides (
$$^3\hbox {H}$$
, $$^{14}\hbox {C}$$
, $$^{63}\hbox {Ni}$$
and $$^{55}\hbox {Fe}$$
), with dedicated LSC systems and several commercial LSC cocktails. The results show that some of the parameters of the cross-correlation distribution such as the peak height or the kurtosis can be used as detection efficiency estimators or quenching indicators in LSC. Thus, although the time domain and the cross-correlation distribution have received little to no attention in the practice of LSC, they have the capacity to bring significant improvements in almost all LSC applications related to activity determination of low-energy beta-emitting and electron-capture radionuclides. The results also suggest concepts for the development of innovative LSC systems.
2 citations
References
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TL;DR: In this article, standards for reporting C-14 age determinations are discussed, and the statistical uncertainty (plus or minus one standard deviation) expresses counting errors, inaccuracies in voltage, pressure, temperature, dilution, and should include errors in C-13 ratios.
Abstract: Standards for reporting C-14 age determinations are discussed. All dates should be related either directly or indirectly to the NBS oxalic acid standard. Corrections for isotopic fractionation are also desirable. For some materials, particularly marine shell, corrections for reservoir effect are necessary, but these should always be reported separately from the conventional radiocarbon age. The statistical uncertainty (plus or minus one standard deviation) expresses counting errors, inaccuracies in voltage, pressure, temperature, dilution, and should include errors in C-13 ratios. Errors can be significant when isotope ratios are estimated rather than measured directly. The error in the conventional C-14 half life is not included. The article includes tables indicating what data should be reported.
5,579 citations
01 Jan 2000
TL;DR: This annex is aimed at providing a sound basis for conclusions regarding the number of significant radiation accidents that have occurred, the corresponding levels of radiation exposures and numbers of deaths and injuries, and the general trends for various practices, in the context of the Committee's overall evaluations of the levels and effects of exposure to ionizing radiation.
Abstract: NOTE The report of the Committee without its annexes appears as Official Records of the General Assembly, Sixty-third Session, Supplement No. 46. The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The country names used in this document are, in most cases, those that were in use at the time the data were collected or the text prepared. In other cases, however, the names have been updated, where this was possible and appropriate, to reflect political changes. Scientific Annexes Annex A. Medical radiation exposures Annex B. Exposures of the public and workers from various sources of radiation INTROdUCTION 1. In the course of the research and development for and the application of atomic energy and nuclear technologies, a number of radiation accidents have occurred. Some of these accidents have resulted in significant health effects and occasionally in fatal outcomes. The application of technologies that make use of radiation is increasingly widespread around the world. Millions of people have occupations related to the use of radiation, and hundreds of millions of individuals benefit from these uses. Facilities using intense radiation sources for energy production and for purposes such as radiotherapy, sterilization of products, preservation of foodstuffs and gamma radiography require special care in the design and operation of equipment to avoid radiation injury to workers or to the public. Experience has shown that such technology is generally used safely, but on occasion controls have been circumvented and serious radiation accidents have ensued. 2. Reviews of radiation exposures from accidents have been presented in previous UNSCEAR reports. The last report containing an exclusive chapter on exposures from accidents was the UNSCEAR 1993 Report [U6]. 3. This annex is aimed at providing a sound basis for conclusions regarding the number of significant radiation accidents that have occurred, the corresponding levels of radiation exposures and numbers of deaths and injuries, and the general trends for various practices. Its conclusions are to be seen in the context of the Committee's overall evaluations of the levels and effects of exposure to ionizing radiation. 4. The Committee's evaluations of public, occupational and medical diagnostic exposures are mostly concerned with chronic exposures of …
3,924 citations
TL;DR: Quantitative recoveries were obtained in 60 min by deposition on to a silver plate in a special holder from 50 ml solution at 85–90° with sodium citrate present.
860 citations
TL;DR: Using radiocarbon measurements of winter monsoon aerosols from western India and the Indian Ocean, it is determined that biomass combustion produced two-thirds of the bulk carbonaceous aerosols, as well as one-half and two- thirds of two black carbon subfractions, respectively.
Abstract: Carbonaceous aerosols cause strong atmospheric heating and large surface cooling that is as important to South Asian climate forcing as greenhouse gases, yet the aerosol sources are poorly understood. Emission inventory models suggest that biofuel burning accounts for 50 to 90% of emissions, whereas the elemental composition of ambient aerosols points to fossil fuel combustion. We used radiocarbon measurements of winter monsoon aerosols from western India and the Indian Ocean to determine that biomass combustion produced two-thirds of the bulk carbonaceous aerosols, as well as one-half and two-thirds of two black carbon subfractions, respectively. These constraints show that both biomass combustion (such as residential cooking and agricultural burning) and fossil fuel combustion should be targeted to mitigate climate effects and improve air quality.
633 citations