1、Designation: D1890 15 (Reapproved 2017)Standard Test Method forBeta Particle Radioactivity of Water1This standard is issued under the fixed designation D1890; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This test method covers the measurement of b
3、eta par-ticle activity of water. It is applicable to beta emitters havingmaximum energies above 0.1 MeV and at activity levels above0.02 Bq/mL(540 pCi/L) of radioactive homogeneous water formost counting systems. This test method is not applicable tosamples containing radionuclides that are volatile
4、 under con-ditions of the analysis.1.2 This test method can be used for either absolute orrelative determinations. In tracer work, the results may beexpressed by comparison with a standard which is defined to be100 %. For radioassay, data may be expressed in terms of aknown radionuclide standard if
5、the radionuclides of concernare known and no fractionation occurred during processing, ormay be expressed arbitrarily in terms of some other standardsuch as137Cs. General information on radioactivity and mea-surement of radiation may be found in the literature2, 3, 4, 5andPractices D3648.1.3 The val
6、ues stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 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 sa
7、fety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment o
8、f International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:6D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precision an
9、d Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3648 Practices for the Measurement of Radioactivity3. Terminology3.1 Definitions:3.1.1 For terms not defined in this standard or in Terminol-ogy D1129, reference may be made to other pub
10、lished glossa-ries.3.2 Definitions of Terms Specific to This Standard:3.2.1 becquerel, na unit of radioactivity equivalent to 1nuclear transformation per second.3.2.2 beta energy, maximum, nthe maximum energy of thebeta-particle energy spectrum produced during beta decay of agiven radioactive specie
11、s.3.2.2.1 DiscussionSince a given beta-particle emitter maydecay to several different quantum states of the productnucleus, more than one maximum energy may be listed for agiven radioactive species.3.2.3 counter background, nin the measurement ofradioactivity, the counting rate resulting from factor
12、s otherthan the radioactivity of the sample and reagents used.3.2.3.1 DiscussionCounter background varies with thelocation, shielding of the detector, and the electronics; itincludes cosmic rays, contaminating radioactivity and electri-cal noise.1This test method is under the jurisdiction of ASTM Co
13、mmittee D19 on Waterand is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemi-cal Analysis.Current edition approved Dec. 15, 2017. Published December 2017. Originallyapproved in 1961. Last previous edition approved in 2015 as D1890 15. DOI:10.1520/D1890-15R17.2Friedlander, G.,
14、 et al., Nuclear and Radiochemistry, 3rd Ed., John Wiley andSons, Inc., New York, NY, 1981.3Price, W. J., Nuclear Radiation Detection, 2nd Ed., McGraw-Hill Book Co.,Inc., New York, NY, 1964.4Lapp, R. E., and Andrews, H. L., Nuclear Radiation Physics, 4th Ed.,Prentice-Hall Inc., New York, NY, 1972.5O
15、verman, R. T., and Clark, H. M., Radioisotope Techniques, McGraw-HillBook Co., Inc., New York, NY, 1960.6For 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 standard
16、s Document Summary page onthe ASTM website.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 Decisio
17、n on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.4 counter beta-particle effciency, nin the measure-ment of radioactivity, that fraction of beta particles emitted bya sour
18、ce which is detected by the counter.3.2.5 counter effciency, nin the measurement ofradioactivity, that fraction of the disintegrations occurring in asource which is detected by the counter.3.2.6 radioactive homogeneous water, nwater in whichthe radioactive material is uniformly dispersed throughout
19、thevolume of water sample and remains so until the measurementis completed or until the sample is evaporated or precipitatingreagents are added to the sample.3.2.7 reagent background, nin the measurement of radio-activity of water samples, the counting rate observed when asample is replaced by mock
20、sample salts or by reagentchemicals used for chemical separations that contain noanalyte.3.2.7.1 DiscussionReagent background varies with thereagent chemicals and analytical methods used and may varywith reagents from different manufacturers and from differentprocessing lots.4. Summary of Test Metho
21、d4.1 Beta radioactivity may be measured by one of severaltypes of instruments composed of a detecting device andcombined amplifier, power supply, and scalerthe mostwidely used being proportional or Geiger-Mller counters.Where a wide range of counting rates is encountered (0.1 to1300 counts per secon
22、ds), the proportional-type counter ispreferable due to a shorter resolving time and greater stabilityof the instrument. The test sample is reduced to the minimumweight of solid material having measurable beta activity byprecipitation, ion exchange resin, or evaporation techniques.Beta particles ente
23、ring the sensitive region of the detectorproduce ionization of the counting gas. The negative ion of theoriginal ion pair is accelerated towards the anode, producingadditional ionization of the counting gas and developing avoltage pulse at the anode. By use of suitable electronicapparatus, the pulse
24、 is amplified to a voltage sufficient foroperation of the counter scaler. The number of pulses per unitof time is related to the disintegration rate of the test sample.The beta-particle efficiency of the system can be determined byuse of prepared standards having the same radionuclide com-position a
25、s the test specimen and equivalent residual platedsolids. An arbitrary efficiency factor can be defined in terms ofsome other standard such as cesium-137.5. Significance and Use5.1 This test method was developed for the purpose ofmeasuring the gross beta radioactivity in water. It is used forthe ana
26、lysis of both process and environmental water todetermine gross beta activity.6. Measurement Variables6.1 The relatively high absorption of beta particles in thesample media and any material interposed between source andsensitive volume of the counter results in an interplay of manyvariables which a
27、ffect the counting rate of the measurement.Thus, for reliable relative measurements, hold all variablesconstant while counting all test samples and standards. Forabsolute measurements, appropriate correction factors are ap-plied. The effects of geometry, backscatter radiation, sourcediameter, self-s
28、catter and self-absorption, absorption in air anddetector window for external counters, and counting coinci-dence losses have been discussed2, 3, 4, 5and may be describedby the following relation:cps 5 BqbGp!fbs!faw!fd!fssa!fc! (1)where:cps = recorded counts per second corrected for background,Bqb=
29、disintegrations per second yielding beta particles,Gp= point source geometry (defined by the solid anglesubtended by the sensitive area of the detector),fbs= backscatter factor or ratio of cps with backing to cpswithout backing,faw= factor to correct for losses due to absorption in the airand window
30、 of external detectors. It is equal to theratio of the actual counting rate to that which wouldbe obtained if there were no absorption by the air andwindow between the source and sensitive volume ofthe detector. Expressed in terms of absorption coef-ficient and density of absorber, faw= ex, where =
31、absorption coefficient, in square centimetres permilligram, and x = absorber density in milligrams persquare centimetre.fd= factor to correct a spread source counting rate to thecounting rate of the same activity as a point source onthe same axis of the system,fssa= factor to correct for the absorpt
32、ion and scatter of betaparticles within the material accompanying the radio-active element, andfc= factor for coincident events to correct the countingrate for instrument resolving time losses and definedby the simplified equation, fc=1nr, where, n = theobserved counts per second, and r = instrument
33、 re-solving time in seconds. Generally, the sample size orsource to detector distance is varied to obtain acounting rate that precludes coincident losses. Infor-mation on the effect of random disintegration andinstrument resolving time on the sample count rate aswell as methods for determining the r
34、esolving time ofthe counting system may be found in the literature.For most applications, a detector system is calibrated usinga single beta emitting radionuclide and an efficiency ofdetection, fo, response curve generated for various sampleresidue weights. The efficiency of detection for each sampl
35、eresidual weight incorporates all the factors mentioned above sothat:fo5 cps/Bq 5 Gp!fbs!faw!fd!fssa!fc! (2)6.1.1 In tracer studies or tests requiring only relative mea-surements in which the data are expressed as being equivalentto a defined standard, the above correction factors can besimply combi
36、ned into a counting efficiency factor. The use ofa counting efficiency factor requires that sample mounting,density of mounting dish, weight of residue in milligrams persquare centimetre, and radionuclide composition, in addition toD1890 15 (2017)2conditions affecting the above described factors, re
37、main con-stant throughout the duration of the test and that the compara-tive standard be prepared for counting in the same manner asthe test samples. The data from comparative studies betweenindependent laboratories, when not expressed in absolute units,are more meaningful when expressed as percenta
38、ge relation-ships or as the equivalent of a defined standard. Expressing thedata in either of these two ways minimizes the differences incounters and other equipment and in techniques used by thelaboratories conducting the tests.6.2 The limit of sensitivity for both Geiger-Mller andproportional coun
39、ters is a function of the background countingrate. Massive shielding or anti-coincidence detectors andcircuitry, or both, are generally used to reduce the backgroundcounting rate to increase the sensitivity.7. Interferences7.1 Material interposed between the test sample and theinstrument detector, a
40、s well as increasing density in the samplecontaining the beta emitter, produces significant losses insample counting rates. Liquid samples are evaporated todryness in dishes that allow the sample to be counted directlyby the detector. Since the absorption of beta particles in thesample solids increa
41、ses with increasing density and variesinversely with the maximum beta energy, plated solids shallremain constant between related test samples and shouldduplicate the density of the solids of the plated standard.7.2 Most beta radiation counters are sensitive to alpha,gamma, and X-ray radiations, with
42、 the degree of efficiencydependent upon the type of detector.2, 3, 4, 5The effect ofinterfering radiations on the beta counting rate is more easilyevaluated with external-type counters where appropriate ab-sorbers can be used to evaluate the effects of interferingradiation.8. Apparatus8.1 Beta Parti
43、cle Counter, consisting of the following com-ponents:8.1.1 DetectorThe end-window Geiger-Mller tube andthe internal or external sample gas-flow proportional chambersare the two most prevalent commercially available detectortypes. The material used in the construction of the detectorshould be free fr
44、om detectable radioactivity. When detectorscontain windows, the manufacturer shall supply the windowdensity expressed in milligrams per square centimetre. Toestablish freedom from undesirable characteristics, the manu-facturer shall supply voltage plateau and background countingrate data. Voltage pl
45、ateau data shall show the threshold voltage,slope, and length of plateau. Detectors requiring externalpositioning of the test sample are mounted on a tube support oflow-density material (aluminum or plastic) and positioned sothe center of the window is directly above the center of the testsample. Th
46、e distance between the detector window and testsample plays an important part in determining the geometry ofthe system and can be varied for external counters to corre-spond more favorably with such factors as activity level,source size, sensitivity requirements, energy of beta particles,etc. A conv
47、enient arrangement is to combine the tube mountwith a sample holder containing slots for positioning thesample at three or four distances from the detector window,varying from approximately 5 to 100 mm from tube flange.8.1.2 Detector ShieldThe detector assembly is surroundedby an external radiation
48、shield of massive metal equivalent toapproximately 51 mm of lead and lined with 3.2-mm thickaluminum. The material of construction should be free fromdetectable radioactivity. The shield has a door or port forinserting or removing specimens. Detectors having other thancompletely opaque windows are l
49、ight sensitive. The design ofthe shield and its openings shall eliminate direct light paths tothe detector window; beveling of door and opening is generallysatisfactory. The percentage of the beta particles scattered fromthe walls of the shield into the detector can be reduced byincreasing the internal diameter of the shield. The use of adetector without a shield will significantly increase the back-ground and the detection capability.8.1.3 ScalerNormally the scaler, mechanical register,power supply, and amplifier are contained in a single chassis,
