1、Designation:D793821Standard Practice forSampling of C-14 in Gaseous Effluents1This standard is issued under the fixed designation D7938;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses
2、 indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 The intended use of this practice is for sampling ofgasses containing14C in inorganic,organic or particulateforms.This sampling practice captures the14C in a me
3、dia thatcan be submitted to a laboratory for analysis,typically byliquid scintillation counting(LSC)1.2 This practice does not include the needed steps for theliberation of14C from the media on which it was adsorbed orthose for the preparation for LSC sample preparation in thelaboratory prior to liq
4、uid scintillation analysis.This practicedoes not include the methodology used to analyze the preparedsamples by LSC.1.3 The overall14C analytical detection capability is im-pacted by a number of factors including the volume sampled,the method used to desorb the14C from the media,and theanalytical me
5、thod used the measure14C from the media.Thispractice only directly addresses the volume of the gas streamfrom which any present14C would be adsorbed.1.4 The values stated in pCi units are to be regarded asstandard given the reporting requirements of the U.S.NRCRegulatory Guide 1.21.The Bq values giv
6、en in parenthesis aremathematical conversions to SI units that are provided forinformation only and are not considered standard.Other valuesstated in SI units are to be regarded as standard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is t
7、heresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standar
8、d-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD7282 Practice fo
9、r Set-up,Calibration,and Quality Controlof Instruments Used for Radioactivity MeasurementsD7902 Terminology for Radiochemical Analyses2.2 U.S.NRC Publications:3U.S.NRC Regulatory Guide 1.21“Measuring,Evaluating,and Reporting Radioactive Material in Liquid and Gas-eous Effluents and Solid Waste,”revi
10、sion 2,June 20093.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard,refer toTerminologies D1129 and D7902.3.2 Definitions of Terms Specific to This Standard:3.2.1 organic14C,nany gaseous,chemical14C form(including CO)that is not particulate and not CO2.3.2.1.1 Discussio
11、nAlthough no specific organic form isdetermined,the major contributors are likely to be CH4,C2H6,C2H4,CO,and C2H2.3.2.2 inorganic14C,nthe gaseous,chemical form of14Cas CO2.3.2.2.1 DiscussionThese chemical form categorizationsare based on U.S.NRC Regulatory Guide 1.21.4.Summary of Practice4.1 A sampl
12、e of a flowing gaseous stream is extracted at aflow rate of 30 to 3000 mL/min.The sample is filtered and splitinto two parallel flow paths.One flow path is passed through afurnace to convert all carbon to CO2.This will yield a total14Ccontent of the sample.The other flow path collects only theCO2fra
13、ction of the gaseous stream.This yields the inorganic14C content of the gaseous stream.The calculated differencebetween the measured total and inorganic carbon content is theorganic content(U.S.NRC Regulatory Guide 1.21).Theconcentration of14C in the particulate matter may also bedetermined.1This pr
14、actice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.04 on Methods of RadiochemicalAnalysis.Current edition approved Dec.15,2021.Published February 2022.Originallyapproved in 2015.Last previous edition approved in 2015 as D7938 15.DOI:10
15、.1520/D7938-21.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from U.S.Nuclear Regulatory Commission,W
16、ashington,DC 20555-0001,http:/www.nrc.gov.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.15.Significance and Use5.1 This prac
