1、Designation: D 6327 98 (Reapproved 2004)Standard 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 D 6327; the number immediately following the designation indicat
2、es the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method provides instruction for us
3、ing the grabsampling 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 re
4、presentative of closed-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, bu
5、t a greater degreeof 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 sampl
6、ing. The results obtained 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 obt
7、ained for diagnostic 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
8、for measurementswithin typical residential or building environments and maynot necessarily apply to specialized circumstances, for ex-ample, clean rooms.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of th
9、is 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 Documents2.1 ASTM Standards:2D 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 1605 Pract
10、ices for SamplingAtmospheres forAnalysis ofGases and VaporsD 3631 Test Methods for Measuring Surface AtmosphericPressureE1 Specification for ASTM Thermometers3. Terminology3.1 Definitions For definitions of terms used in this testmethod, refer to Terminology D 1356.3.2 Definitions of Terms Specific
11、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-214.3.2.3 grab samplingthe act and all procedures involvedwith obtaining a short term sample through the use of anoperati
12、ng 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 forexpressing environmental RDP exposure.4. Summary of Test Method34.1 Grab sampling measurements of RDP concentration
13、s inair are performed by collecting the RDP from a known volumeof air on a filter and subsequently counting the activity 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 i
14、s converted1This 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 February 1, 2004. Published March 2004. Originallyapproved in 1998. Last previous edition approved in 1998 as D 63
15、27 - 98.2For 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.3Thomas, J.W. “Measurement of Radon Daughters in Air,
16、” Health Physics, Vol23, 1972, p. 783.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.to light pulses by a zinc sulfide phosphor in contact with thefilter. The light pulses are detected and converted to counts.Analysis of the number
17、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 relatively simple method fordetermination of the conc
18、entration 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 are generally fordiagnostic purposes and are
19、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 exposures.The measurement of RDP, which are
20、 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 of inducing a light pulse in the phosphorsc
21、reen 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 to which thoron decay products interfere can
22、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 directionof interferences is always negative.7. Appar
23、atus7.1 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 Membrane filters, mixed cellulose ester, 25
24、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 tube.7.2.3 High voltage power supply.7.3 Th
25、ermometer, (See Specification E1).7.4 Barometer, (See Test Methods D 3631).8. Reagents and Materials8.1 National Institute of Standards and Technology (NIST)traceable alpha calibration source, typically americium-241, todetermine counter efficiency.6,79. Hazards9.1 Since radioactive material is bein
26、g 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 respi-rator during sampling.9.3 The calibr
27、ation 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 Apparatus10.1 Verify proper operation of the equi
28、pment 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. Eachmanufacturers counting systems have different
29、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 pump, filter assembly, and connecting tubin
30、gshall 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 themeter in the laboratory prior to use with a positive displace-ment liquid meter or a cylinder and pist
31、on flow calibrator, anddetermine a meter correction factor, CM, as necessary.10.5 Locate the 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 s
32、tart of counting.11. Procedure11.1 Calibration of Scintillation Counter: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
33、 on Radiation Protection and Measurements, 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, Unit
34、ed States Department of Commerce, Springfield, 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 fo
35、r Radon Grab Sampling, Revision 02, March 31, 1992;GJ/TMC Technical Procedure RN-GRAB-U, United States Department of Energy,Washington D.C.D 6327 98 (2004)211.1.1 Determine the efficiency of the scintillation counterthrough use of the NIST-traceable alpha-emitting calibrationpoint source.11.1.2 Deac
36、tivate the photomultiplier tube. Exposure of anactivated photomultiplier tube to light while connected topower may permanently damage the photomultiplier tube.NOTE 1Although comments have been received indicating any lightincident on the deactivated photomultiplier tube, even though completelydiscon
37、nected from power, will result in spurious addition/deletions of lightpulses. Tests conducted with four photomultiplier tubes of two designs atthe Grand Junction DOE Facility Radon Chamber indicated no variationin background counts from photomultiplier tubes kept in the dark versusthe same tubes wit
38、h 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 photomultiplier tube. Thephotomultiplier shall not be opened to light while activated orthe electronics will be shocked. It is very im
39、portant 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 shall be longenough to obtain at least 10 000 counts from the alpha-emittingsource. The number of counts obtained from the phos
40、phor 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 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.
41、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.11.1.9 Activate the scintillation counter for the countinginterval, CI, and the number counts obtained is the measuredcalibratio
42、n 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 fresh phosphor disc at the center of thephotomultiplier lens. Select a sampling filter with the forceps,and inspect the filter to
43、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 phosphor disc. Secure the filter to the phosphor disc,and ensure complete contact by placing a flat cover plate overthe filte
44、r. 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 everyset of measurements, utilize a phosphor disc that no longershows enhanced activity from previous sampling measure-ments. Use the
45、 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 pairand recount. The number is the background count, B, and isrecorded in counts.11.2.4 Remove the filter from the phosphor d
46、isc 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.11.2.6 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
47、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 phosphor disc withwhich the background was just previously measured (exposedsample filter side oriented toward the phosphor disc).
48、 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 tube.11.3 Sample Counting Two different counting techniquesare described in this section, a modified Tsivoglou Technique(see 1
49、1.3.1) 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)6to20min(14min)M(21-30)21 to 30 min (9 min)Record the total number of counts during each time intervalMab,M(2-5),M(6-20), and M(21-3
