1、Designation: D6327 10Standard Test Method forDetermination of Radon Decay Product Concentration andWorking Level in Indoor Atmospheres by Active Samplingon a Filter1This standard is issued under the fixed designation D6327; the number immediately following the designation indicates the year oforigin
2、al adoption or, in the 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 test method provides instruction for using the grabsampling
3、filter technique to determine accurate and reproduc-ible measurements of indoor radon decay product (RDP)concentrations and of the working level value corresponding tothose concentrations.1.2 Measurements made in accordance with this test methodwill produce RDP concentrations representative of close
4、d-building conditions. Results of measurements made underclosed-building conditions will have a smaller variability andare more reproducible than measurements obtained whenbuilding conditions are not controlled. This test method may beutilized under non-controlled conditions, but a greater degreeof
5、variability in the results will occur. Variability in the resultsmay also be an indication of temporal variability present at thesampling site.1.3 This test method utilizes a short sampling period and theresults are indicative of the conditions only at the place andtime of sampling. The results obta
6、ined by this test method arenot necessarily indicative of longer terms of sampling andshould not be confused with such results. The averaging ofmultiple measurements over hours and days can, however,provide useful screening information. Individual measure-ments are generally obtained for diagnostic
7、purposes.1.4 The range of the test method may be considered from0.0005 WL to unlimited working levels (WL), and from 40Bq/m3 to unlimited for each individual randon decay product.1.5 This test method provides information on equipment,procedures, and quality control. It provides for measurementswithi
8、n typical residential or building environments and maynot necessarily apply to specialized circumstances, for ex-ample, clean rooms.1.6 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.7 This standard does not purport to addres
9、s 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 health practices and determine the applica-bility of regulatory limitations prior to use. See Section 9 foradditional precautions.2. Referenced Docu
10、ments2.1 ASTM Standards:2D1356 Terminology Relating to Sampling and Analysis ofAtmospheresD1605 Practices for Sampling Atmospheres for Analysis ofGases and VaporsD3631 Test Methods for Measuring Surface AtmosphericPressureE1 Specification for ASTM Liquid-in-Glass Thermometers3. Terminology3.1 Defini
11、tions For definitions of terms used in this testmethod, refer to Terminology D1356.3.2 Definitions of Terms Specific to This Standard:3.2.1 radonthe particular isotope Radon-222.3.2.2 radon decay products (RDP)any or all of theparticular isotopes polonium-218, bismuth-214, lead-214, andpolonium-214.
12、3.2.3 grab samplingthe act and all procedures involvedwith obtaining a short term sample through the use of anoperating air pump.3.2.4 working levelquantity of short-lived decay productsthat will result in 1.3 3 106MeV of potential alpha energy perliter of air. The working level is the common unit f
13、orexpressing environmental RDP exposure.1This test method is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.05 on Indoor Air.Current edition approved May 1, 2010. Published June 2010. Originallyapproved in 1998. Last previous edition a
14、pproved in 2004 as D6327 - 98R04. DOI:10.1520/D6327-10.2For 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.1Copyr
15、ight ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Test Method34.1 Grab sampling measurements of RDP concentrations inair are performed by collecting the RDP from a known volumeof air on a filter and subsequently counting the ac
16、tivity on thefilter following collection. The counting is performed atspecified times for specified periods. The energy from radio-active decay of the particles collected on the filter is convertedto light pulses by a zinc sulfide phosphor in contact with thefilter. The light pulses are detected and
17、 converted to counts.Analysis of the number of counts in each counting intervaldetermines the concentrations of the RDP. The two countingmethods which have found the most general use are theKusnetz and the modified Tsivoglou procedures.45. Significance and Use5.1 The test method provides a relativel
18、y simple method fordetermination of the concentration of RDP without the need forspecialty equipment built expressly for such purposes.5.2 Using this test method will afford investigators of radonin dwellings a technique by which the RDP can be determined.The use of the results of this test method a
19、re generally fordiagnostic purposes and are not necessarily indicative of resultsthat might be obtained by longer term measurement methods.5.3 An improved understanding of the frequency of elevatedradon in buildings and the health effect of exposure hasincreased the importance of knowledge of actual
20、 exposures.The measurement of RDP, which are the direct cause ofpotential adverse health effects, should be conducted in amanner that is uniform and reproducible; it is to this end thatthis test method is addressed.6. Interferences6.1 Interferences may be caused by any alpha-emittingparticle capable
21、 of inducing a light pulse in the phosphorscreen used for alpha-counting. In general, the only significantinterference source is that of the decay products of radon-220,thoron, which may be considerable in certain geographicalregions. The direction of the interference is always positive.The extent t
22、o which thoron decay products interfere can beestimated or measured through alpha-spectroscopy or serialtype measurements.56.2 Some depth penetration to the filter may occur. Theextent of the penetration may be estimated using membranefilter types not suggested within this test method. The direction
23、of interferences is always negative.7. Apparatus7.1 Collection Apparatus:7.1.1 Air pump capable of 10 to 12 L/min flow rate.7.1.2 Bubble tube airflow calibration cell, 1 L or larger.7.1.3 Calibrated dry gas meter.7.1.4 Flow meter (optional).7.1.5 Open-faced filter holder, 25 or 47-mm diameter.7.1.6
24、Membrane filters, mixed cellulose ester, 25 or 47-mmdiameter, 0.8-m pore size.7.1.7 Sharpened forceps, for removal of sample filters.7.1.8 Stopwatch, accurate to 1 s.7.2 Decay Counting Apparatus:7.2.1 Zinc sulfide phosphor discs, 51-mm diameter.7.2.2 Scintillation Counter, scaler and photomultiplier
25、 tube.7.2.3 High voltage power supply.7.3 Thermometer, (See Specification E1).7.4 Barometer, (See Test Methods D3631).8. Reagents and Materials8.1 National Institute of Standards and Technology (NIST)traceable alpha calibration source, typically americium-241, todetermine counter efficiency.6,79. Ha
26、zards9.1 Since radioactive material is being utilized, both in theform of calibration standards and particles collected on samplefilters, wear disposable gloves during handling of these items.9.2 If the atmospheres being measured are known to containhigh concentrations of RDP, wear an HEPA half-mask
27、 respi-rator during sampling.9.3 The calibration source from NIST must be shieldedwhen not being used for calibration. Shield the source byreturning the source to the original NIST storage container andplacing the source in the original storage geometry within thecontainer.610. Preparation of Appara
28、tus10.1 Verify proper operation of the equipment prior tocollection of the sample. Refer to equipment manuals forinformation.10.1.1 Operate each counting system at the high-voltage(HV) and threshold settings that combines maximum stability,good counting efficiency, and low background counts. Eachman
29、ufacturers counting systems have different set-up require-ments and optimization procedures. A general similar proce-dure is available.810.2 Determine the counter efficiency and background forthe sampling filter and phosphor screen pair prior to collectionof the sample (see Section 11).10.3 The air
30、pump, filter assembly, and connecting tubingshall not leak.10.4 A volume meter is needed for measuring total sampleflow. A calibrated dry gas test meter is the most satisfactorytotal volume meter available for source test work. Calibrate the3Thomas, J.W. “Measurement of Radon Daughters in Air,” Heal
31、th Physics, Vol23, 1972, p. 783.4Indoor Radon and Randon Decay Product Measurement Protocols, EPA402R92004, July 1992, United States Environmental Agency, Washington D.C.5Measurement of Radon and Radon Decay Products in Air, NCRP Report No.97, National Council on Radiation Protection and Measurement
32、s, Bethesda, MD20814, Nov. 15, 1988.6Interlaboratory Radon-Daughter Measurement Comparison Workshop: 9-12September 1985, GJ/TMC-25 UC-70A, United States Department of Energy,Washington D.C. Available through: NIST, National Technical Information Ser-vice, United States Department of Commerce, Spring
33、field, VA 22161.7Available from: NIST Standard Reference Materials Catalog, NIST SpecialPublication 260, U.S. Department of Commerce, Nation Institute of Standards andTechnology 1990-1991, Issued January 1990, as Catalog SRM No. 4904NG.8Standard Test Method for Radon Grab Sampling, Revision 02, Marc
34、h 31, 1992;GJ/TMC Technical Procedure RN-GRAB-U, United States Department of Energy,Washington D.C.D6327 102meter in the laboratory prior to use with a positive displace-ment liquid meter or a cylinder and piston flow calibrator, anddetermine a meter correction factor, CM, as necessary.10.5 Locate t
35、he scintillation counter to provide rapid accessfrom the sampling site when the modified Tsivoglou countingprocedure is utilized. This process is necessary due to the shorttime period between sampling and the start of counting.11. Procedure11.1 Calibration of Scintillation Counter:11.1.1 Determine t
36、he efficiency of the scintillation counterthrough use of the NIST-traceable alpha-emitting calibrationpoint source.11.1.2 Deactivate the photomultiplier tube. Exposure of anactivated photomultiplier tube to light while connected topower may permanently damage the photomultiplier tube.NOTE 1Although
37、comments have been received indicating any lightincident on the deactivated photomultiplier tube, even though completelydisconnected from power, will result in spurious addition/deletions of lightpulses. Tests conducted with four photomultiplier tubes of two designs atthe Grand Junction DOE Facility
38、 Radon Chamber indicated no variationin background counts from photomultiplier tubes kept in the dark versusthe same tubes with large mercury arc lamps over the tubes.11.1.3 Place a fresh phosphor disc (phosphor side up) at thecenter of the photomultiplier lens.11.1.4 Cover and activate the photomul
39、tiplier tube. Thephotomultiplier shall not be opened to light while activated orthe electronics will be shocked. It is very important that therebe no power to the opened photomultiplier.11.1.5 Activate the scintillation counter for a defined count-ing interval in minutes, CI. The counting interval s
40、hall be longenough to obtain at least 10 000 counts from the alpha-emittingsource. The number of counts obtained from the phosphor isthe background count, Bcal.11.1.6 Deactivate the photomultiplier tube.11.1.7 Determine the calibration source count. Using for-ceps, place the calibration point source
41、 on top and in the centerof the same phosphor disc as used in 11.1.3.11.1.8 Cover and then activate the photomultiplier tube. Thephotomultiplier shall not be opened to light while activated orthe electronics will be shocked. It is very important that therebe no power to the opened photomultiplier.11
42、.1.9 Activate the scintillation counter for the countinginterval, CI, and the number counts obtained is the measuredcalibration count, Mcal.11.1.10 Calculate the efficiency of the counter using theequation in 12.2.11.2 Sample Measurement:11.2.1 Deactivate the photomultiplier tube.11.2.2 Place a fres
43、h phosphor disc at the center of thephotomultiplier lens. Select a sampling filter with the forceps,and inspect the filter to determine if any tears are present: if so,discard. Place an acceptable sampling filter on top at the centerof the phosphor disc, making sure the sampling surface istoward the
44、 phosphor disc. Secure the filter to the phosphor disc,and ensure complete contact by placing a flat cover plate overthe filter. The cover plate shall completely cover the filter andhave been previously checked to ensure no count contribution.11.2.3 Obtain a count measurement for 10 min. For everyse
45、t of measurements, utilize a phosphor disc that no longershows enhanced activity from previous sampling measure-ments. Use the same phosphor disc for a filter before and aftercollection of a sample with the filter. If the total count for 10min is greater than 10, replace the filter and phosphor disc
46、 pairand recount. The number is the background count, B, and isrecorded in counts.11.2.4 Remove the filter from the phosphor disc with theforceps and place in the filter holder with the counted sideexposed to the air.11.2.5 Reassemble the filter holder with care to preventtearing of the filter.11.2.
47、6 Obtain the initial dry gas meter reading.11.2.7 Draw sample air through the filter for 5.00 min.11.2.8 Obtain the final dry gas meter reading and record thevolume of air sampled in liters, V.11.2.9 Disassemble the filter holder, and carefully transferthe filter from the filter holder onto the phos
48、phor disc withwhich the background was just previously measured (exposedsample filter side oriented toward the phosphor disc). Duringthe transfer, inspect the filter for tears. If a tear is found, discardand begin again. Cover the filter with the cover plate. Coverand reactivate the photomultiplier
49、tube.11.3 Sample Counting Two different counting techniquesare described in this section, a modified Tsivoglou Technique(see 11.3.1) and a Kusnetz Technique (see 11.3.2). Eachtechnique requires a unique set of counting intervals.Addition-ally, each technique requires a separate set of calculations aslisted in Section 12.11.3.1 Modified Tsivoglou TechniqueOperate the scintil-lation counter for the following time intervals. The intervalsare measured from the time the 5.00 min sampling period hasended.Count Designation, M(ab)Time Interval, TM(2-5)2to5min(3min)M(6-20)6to20m
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