ASTM D7784-2012 8750 Standard Practice for the Rapid Assessment of Gamma-ray Emitting Radionuclides in Environmental Media by Gamma Spectrometry《使用伽马能谱测量快速评估在环境介质中释放放射性核素的伽马射线的标准实施.pdf
《ASTM D7784-2012 8750 Standard Practice for the Rapid Assessment of Gamma-ray Emitting Radionuclides in Environmental Media by Gamma Spectrometry《使用伽马能谱测量快速评估在环境介质中释放放射性核素的伽马射线的标准实施.pdf》由会员分享,可在线阅读,更多相关《ASTM D7784-2012 8750 Standard Practice for the Rapid Assessment of Gamma-ray Emitting Radionuclides in Environmental Media by Gamma Spectrometry《使用伽马能谱测量快速评估在环境介质中释放放射性核素的伽马射线的标准实施.pdf(7页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D7784 12Standard Practice for theRapid Assessment of Gamma-ray Emitting Radionuclides inEnvironmental Media by Gamma Spectrometry1This standard is issued under the fixed designation D7784; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the quantification of radionuclidesin environmental media (e.g., w
3、ater, soil, vegetation, food) bymeans of simple preparation and counting with a high-resolution gamma ray detector. Because the practice is de-signed for rapid analysis, extensive efforts to ensure homoge-neity or ideal sample counting conditions are not taken.1.2 The values stated in SI units are t
4、o be regarded asstandard. The values given in parentheses are provided forinformation purposes only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and heal
5、th practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C998 Practice for Sampling Surface Soil for RadionuclidesD1129 Terminology Relating to WaterD3370 Practices for Sampling Water from Closed ConduitsD3648 Practices for the M
6、easurement of RadioactivityD3649 Practice for High-Resolution Gamma-Ray Spectrom-etry of WaterD7282 Practice for Set-up, Calibration, and Quality Controlof Instruments Used for Radioactivity Measurements2.2 Other Documents:PCNUDAT data files National Nuclear Data Center,Brookhaven National Lab, Upto
7、n, NY, USA3. Terminology3.1 Definitionsfor definitions of terms used in thispractice, refer to Terminology D1129.4. Summary of Practice4.1 Following sample collection, sample material is placedin a suitable container for analysis by a gamma spectrometrysystem. A suitable container is defined as a co
8、ntainer whichwill both hold the sample in a fixed geometry and for which thegamma spectrometry system has been calibrated. For solidsamples, the samples may be ground, sieved, or otherwiseprepared for the purpose of volume reduction, homogenization,or conformance to the calibration standard, as desi
9、red.5. Significance and Use5.1 This practice was developed for the rapid determinationof gamma-emitting radionuclides in environmental media. Theresults of the test may be used to determine if the activity ofthese radionuclides in the sample exceeds the action level forthe relevant incident or emerg
10、ency response. The detectionlimits will be dependent on sample size, countingconfiguration, and the detector system in use.5.2 In most cases, a sample container which is large indiameter and short in height relative to the detector willprovide the best gamma-ray detection efficiency. For samplesof w
11、ater or other low-Z materials (e.g., vegetation), there-entrant or Marinelli-style beaker may yield the best gamma-ray detection efficiency.5.3 The density of the sample material and physical param-eters of the sample container (e.g., diameter, height, material)may have significant consequences for
12、the accuracy of thesample analysis as compared to the calibration. For this reason,the ideal calibration material and container (often referred to asgeometry) will be exactly the same as the samples to beanalyzed. Differences in sample container or sample matrixmay introduce significant errors in de
13、tector response, espe-cially at low gamma-ray energies. Every effort should be madeto account for these differences if the exact calibration geom-etry is not available.5.4 This method establishes an empirical gamma-ray spec-trometer calibration using standards traceable to a nationalstandardizing bo
14、dy in a specific geometry selected to ensurethat the container, density, and composition of the standardmatches that of the samples as closely as possible. However, insome cases it may be beneficial to modify such initial calibra-tions using mathematical modeling or extrapolations to an1This practic
15、e is under the jurisdiction ofASTM Committee on Water and is thedirect responsibility of Subcommittee D19.04 on Methods of RadiochemicalAnalysis.Current edition approved Nov. 1, 2012. Published November 2012. DOI:10.1520/D7784122For referenced ASTM standards, visit the ASTM website, www.astm.org, or
16、contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1alternate geometry.
17、 Use of such a model may be acceptable,depending on the measurement quality objectives of theanalysis process, and provided that appropriate compensationto uncertainty estimates are included. The use of such calibra-tion models is best supported by the successful analysis of amethod validation refer
18、ence material (MVRM).5.5 This practice addresses the analysis of numerousgamma-emitting radionuclides in environmental media. Thispractice should be applicable to non-environmental media (forexample, urine, debris, or rubble) that have similar physicalproperties. The key determination of “similar ph
19、ysical proper-ties” is the ability to demonstrate that the gamma spectrometrysystem response to the sample configuration is suitably similarto that for which the system is calibrated.5.6 For the analysis of radionuclides with low gamma-rayemission energies (100 keV), self-absorption of the gamma-ray
20、s in the sample matrix can have a significant adverse effecton detection and quantification. The user should verify thatinstrument calibrations appropriately account for any self-absorption that may result from the sample matrix.5.7 Commonly available energy and efficiency calibrationstandards cover
21、 the energy range of approximately 60 keV to1836 keV. Results obtained using gamma-ray peaks outside theefficiency calibrated energy range will have greater uncertaintynot accounted for in the uncertainty calculations of thispractice. Great care should be taken to review the efficiencycalibration va
22、lues and the shape of the efficiency curve outsidethis range. For greater accuracy in the analysis of radionuclideswhose gamma-ray energies are outside this range, a calibrationstandard which includes radionuclide(s) whose gamma-rayenergies span the energy range of radionuclides of interest isadvise
23、d.6. Interferences6.1 A list of some gamma-ray emitting radionuclides withrelevant data is provided, for information only, in Table 1. Thislist includes radionuclides which may be of interest to agenciesresponding to a large scale radiological event. Through inspec-tion of the list, it becomes appar
24、ent that there are numerousopportunities for interferences based on the gamma energyemissions. For this reason, it is important that the determina-tion of the presence of a given radionuclide be supported by allavailable evidence (e.g., additional gamma-ray emissions).6.2 The data provided in Table
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