1、Designation: D7938 15Standard 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 paren
2、theses 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 th
3、e14C in a media 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 thelaborator
4、y prior to liquid 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
5、theanalytical method 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
6、. The Bq values given 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, associate
7、d with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD7282 Practice for Set-up,
8、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,” revisio
9、n 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 Discus
10、sionAlthough 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
11、.1 A sample of a flowing gaseous stream is extracted at aflow rate of 30 to 3000 mL/min. The sample is filtered, andsplit into two parallel flow paths. One flow path is passedthrough a furnace to convert all carbon to CO2. This will yielda total14C content of the sample. The other flow path collects
12、only the CO2fraction of the gaseous stream. This yields theinorganic14C content of the gaseous stream. The calculateddifference between the measured total and inorganic carbon1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.0
13、4 on Methods of RadiochemicalAnalysis.Current edition approved Dec. 15, 2015. Published February 2016. DOI:10.1520/D7938-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, r
14、efer to the standards Document Summary page onthe ASTM website.3Available from U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, http:/www.nrc.gov.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1content is the organic con
15、tent (U.S. NRC Regulatory Guide1.21). The concentration of14C in the particulate matter mayalso be determined.5. Significance and Use5.1 This practice was developed4for the purpose of sam-pling gaseous effluent streams from a facility that releases14Cin either organic or inorganic forms.5.1.1 For ma
16、ny years14C was not included in gaseous andliquid effluent measurements used for effluent dose calculationsat nuclear power facilities. U.S. NRC Regulatory Guide 1.21now requires14C analysis (either estimated by calculation oractual measurement) and its impact on annual dose in theenvirons of nuclea
17、r plants be evaluated. Based on the revisionsto the Regulatory Guide and NRC guidance to licensees,14Cactivity will need to be reported and evaluated for dosecontribution based on the activity concentration and chemicalform of the14C in the release.5.2 While14C releases may be estimated, the measure
18、mentof actual14C emissions provides a more reliable and accuratemeans of reporting emissions. The chemical form of14C thatyields the greatest dose significance due to uptake by livingorganisms is the inorganic form. Thus the distribution of14Cchemical forms in plant effluents is important in assessi
19、ng theoverall dose impact.5.3 Use of this sampling practice has identified that forpressurized water reactors (PWRs) 90 % of all14C releasedmay be in the organic form during operation, and for boilingwater reactors (BWRs) 95 % over a sample flow rate of 300 to 3000 mLper minute. No reduction in conv
20、ersion efficiency was ob-served as a function of methane concentration or flow rate.7.2 Air Sampling PumpCapacity in the range of 30 to3,000 mL/min.7.3 Two Flow MonitorsCalibrated for air flow in thedesired flow range.7.4 Particulate Filter HolderNormally sized for a 47mmdiameter filter but may be s
21、ized to fit the sample flow.7.5 Desiccant TubeSized for the amount of desiccantneeded for the volume of air to be sampled.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the
22、 specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without increasing thebackground of the measur
23、ement.8.1.1 Some chemicals, even of high purity, contain naturallyoccurring radioactive elements, for example, uranium,actinium, thorium, rare earths and potassium compounds.Also,some chemical reagents, including organic compounds, havebeen found to be contaminated with artificially producedradionuc
24、lides. Consequently, when carrier chemicals are usedin the analysis of low-radioactivity samples, the radioactivity4Holtzclaw, J., “Sample and Analysis Protocol for14C in Gaseous Effluents,”Radioactive Effluent Technical Specifications (RETS) and Radiological Environ-mental Monitoring Programs (REMP
25、) Workshop, San Jose, CA, June 2830, 2010.5Reagent Chemicals, American Society Specifications, American ChemicalSociety, Washington, DC. For suggestions on the testing of reagents not listed by theAmerican Chemical Society, see AnalaR Standards for Laboratory Chemicals,BDH Ltd., Poole, Dorset, U.K.,
26、 and the United States Pharmacopeia and NationalFormulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.D7938 152of the carriers shall be determined under identical analyticalconditions as used for the sample. The radioactivity of thereagents may be considered as background and subtrac
27、ted fromthe test sample counting rate. This increased backgroundreduces the sensitivity of the measurement.8.2 Ascarite II, commercially available6solid material foradsorption of CO2.8.2.1 The use of another material which will trap carbondioxide will be acceptable. However validation of the medi-um
28、s ability to retain carbon dioxide should be verified.8.3 Filter medium, 0.45 m or equivalent, 47mm diameter(or as needed to fit filter holder). The filter material may bepaper, fiberglass, or polymeric.8.4 Desiccant, commercially available material for waterremoval.9. Calibration and Standardizatio
29、n9.1 Put the flow monitoring instrument into operation ac-cording to the manufacturers instructions.9.2 Put the combustion furnace into operation following themanufacturers instructions.10. Sampling10.1 In order to differentiate the three different physical pluschemical forms of14C the sampling appa
30、ratus must contain thedistinct components shown in Fig. 1.10.1.1 The system consists of a particulate filter followed bytwo separate parallel sampling pathways.10.1.2 The top pathway contains a desiccant for adsorbingwater (including tritiated water,3HOH) prior to the adsorbentfor capturing14CO2, a
31、flow meter, and an air sample pump.This pathway will collect14CO2(inorganic14C) but notorganic14C.10.1.3 The bottom pathway is identical to the top pathwayexcept that the first component is a high temperature furnacethat converts organic carbon to CO2. A desiccant is used foradsorbing water (includi
32、ng any tritiated water) prior to theadsorbent. The14CO2can then be captured by the CO2adsorbent. Thus the bottom pathway collects total14C that hasbeen converted to14CO2. The difference between the amountsof14C adsorbed in the two pathways is the amount of organic14C.10.2 The flow monitoring device
33、should be placed inbetween the suction of the sample pump and the CO2adsorbentmaterial (see Fig. 1). This ensures that any additional flow dueto leaks in the pump will not be counted towards the finalsample volume.10.3 Practical sampling times may range from 0.5 hours tomore than 10 hours. This depe
34、nds on the limit of detectiondesired for the particular flow path and the assumed distribu-tion of14C between organic and inorganic forms.10.4 The particulate filter mentioned in 10.1.1 may be usedif14C concentration of the particulate matter is required.Particulate14C captured on the filtration med
35、ium is analyzedseparately. If the measurement quality objectives require onlytotal14C analysis, it is still recommended that the sample befiltered. The particulate filter should be treated separately toensure the conversion to carbon dioxide will be complete priorto radiochemical analysis.10.5 The p
36、receding steps in this section of this practiceshould be used to develop facility specific sampling protocols.Once the samples have been collected they should be submittedfor analysis following standardized methods. A description ofsingle operator test data collected using this sampling practiceand
37、the selected laboratory analysis method is presented inAppendix X1.11. Calculation11.1 A calculation may be required to convert the results ofthe laboratory analysis to the activity per unit volume sampled.11.2 The results of the sample analysis will yield both thetotal14C and inorganic14C activity
38、concentration. These valuesare used for the calculation of organic14C activity concentra-tion based on Eq 1.11.3 The lower flow path in Fig. 1 is designated as “Total14C,” while the upper flow path is designated as “Inorganic14C.”11.4 The organic absolute concentration and fraction of the14C content
39、 of the sample is calculated as:11.4.1 Organic Content, pCi/L:Organic14C,pCiL 5 Total14C 2 Inorganic14C (1)11.4.2 Organic Percent of Total:100 3 Total14C pCi L!2 Inorganic14CpCi L!#Total14CpCi L!(2)11.5 The apparatus shown in Fig. X1.1 was used to removetritium (which would interfere with analysis o
40、f14C) and tosequester the carbon dioxide prior to liquid scintillation analy-sis for14C.12. Quality Control12.1 Field Blank:12.1.1 Generate a compressed air field blank with eachgroup of no more than 20 field samples. The air should be takenfrom a compressed air source (preferably a gas cylinder) th
41、athas not been part of the ambient environs being sampled.12.1.2 Submit the field blank to the laboratory for analysiswith the associated field samples. The concentration of theanalyte found in the field blank should be less than one-half ofthe laboratory reported MDC.12.2 Field Duplicate:12.2.1 If
42、a field duplicate sample is required, either a secondsampling train (as shown in Fig. 1), or a second sampling eventtaken within a very short time frame (minutes) of the firstsample should be employed. Generate a field duplicate with6The sole source of supply of the apparatus known to the committee
43、at this timeis Arthur H. Thomas Company in Swedesboro, NJ, 08085. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.D79
44、38 153each group of not more than 20 samples. These conditions helpto ensure representativeness of the duplicate to the originalsample.12.2.2 Calculate the statistical agreement duplicate errorratio (DER) between the two results. This calculation isperformed using the combined standard uncertainty o
45、f eachresult as shown below:DER 5?ACoriginal2 ACdup?=uc2ACoriginal!1uc2ACdup!(3)where:ACoriginal= original sample activity concentration,ACdup= duplicate sample activity concentration,uc2(ACoriginal) = combined standard uncertainty of the origi-nal sample, anduc2(ACdup) = combined standard uncertain
46、ty of the dupli-cate sample.12.2.3 The value of DER should be less than or equal to 3.0.12.3 Independent Reference Material (IRM):NOTE 1See Holtzclaw, J., “Sample and Analysis Protocol for14C in Gaseous Effluents,” Radioactive Effluent Technical Specifications (RETS) andRadiological Environmental Mo
47、nitoring Programs (REMP) Workshop, San Jose, CA, June 2830, 2010.FIG. 1 Flow of the Gaseous Effluent Sample Through the Sampling DeviceD7938 15412.3.1 A means of verifying the precision and bias of thelaboratory reported sample results can be done by spiking aquantity of carbon dioxide trapping agen
48、t packaged in a similarmanner as associated field samples with a known quantity ofinorganic14C, and drawing a volume of blank air equivalent tothe sample volume, through the trapping agent. Submit theIRM sample to the laboratory for analysis with the associatedfield samples.12.3.2 In the absence of
49、other acceptance criteria for theIRM sample, compare the IRM sample result to the IRMknown value as follows:Z 5?IRMfound2 IRMknown?=uc2IRMfound!1uc2IRMknown!(4)where:Z = the z-score for the comparison,IRMfound= found concentration of the IRM,IRMknown= known concentration of the IRM,uc2(IRMfound) = combined standard uncertainty of the IRMfound concentration, anduc2(IRMknown) = combined standard uncertainty of the IRMknown.12.3.3 The value of Z should be less than or equal to 3.0.13. Keywords13.1 C-14; gaseous effuents; inorganic14C; organic14C
