1、Designation: D1890 05 (Reapproved 2012)D1890 15Standard Test Method forBeta Particle Radioactivity of Water 1This 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 las
2、t revision. 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 measure
3、ment of beta particle activity of water. It is applicable to beta emitters having maximumenergies above 0.1 MeV and at activity levels above 0.02 Bq/mL(540 pCi/L) of radioactive homogeneous water for most countingsystems. This test method is not applicable to samples containing radionuclides that ar
4、e volatile under conditions of the analysis.1.2 This test method can be used for either absolute or relative determinations. In tracer work, the results may be expressed bycomparison with a standard which is defined to be 100 %. For radioassay, data may be expressed in terms of a known radionuclides
5、tandard if the radionuclides of concern are known and no fractionation occurred during processing, or may be expressed arbitrarilyin terms of some other standard such as 137Cs. General information on radioactivity and measurement of radiation may be foundin the literature literature2, 3, 4, 5 and Pr
6、actice D3648.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard t
7、o establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:6D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias of Appli
8、cable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3648 Practices for the Measurement of Radioactivity3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 Becquerela unit of radioactivity equivalent to 1 nuclear transformation per se
9、cond.3.1.2 beta energy, maximumthe maximum energy of the beta-particle energy spectrum produced during beta decay of a givenradioactive species.NOTE 1Since a given beta-particle emitter may decay to several different quantum states of the product nucleus, more than one maximum energymay be listed fo
10、r a given radioactive species.1 This test method is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.04 on Methods of RadiochemicalAnalysis.Current edition approved June 1, 2012Jan. 1, 2015. Published August 2012February 2015. Originally appr
11、oved in 1961. Last previous edition approved in 20052012 asD1890 05.D1890 05 (2012). DOI: 10.1520/D1890-05R12.10.1520/D1890-15.2 Friedlander, G., et al., Nuclear and Radiochemistry, 3rd Ed., John Wiley and Sons, Inc., New York, NY, 1981.Friedlander, G., et al., Nuclear and Radiochemistry , 3rdEd., J
12、ohn Wiley and Sons, Inc., New York, NY, 1981.Price, W. J., Nuclear Radiation Detection, 2nd Ed., McGraw-Hill Book Co., Inc., New York, NY, 1964.Lapp, R. E., and Andrews, H. L., Nuclear Radiation Physics, 4th Ed., Prentice-Hall Inc., New York, NY, 1972.Overman, R. T., and Clark, H. M., Radioisotope T
13、echniques, McGraw-Hill Book Co., Inc., New York, NY, 1960.3 Price, W. J., Nuclear Radiation Detection, 2nd Ed., McGraw-Hill Book Co., Inc., New York, NY, 1964.4 Lapp, R. E., and Andrews, H. L., Nuclear Radiation Physics, 4th Ed., Prentice-Hall Inc., New York, NY, 1972.5 Overman, R. T., and Clark, H.
14、 M., Radioisotope Techniques, McGraw-Hill Book Co., Inc., New York, NY, 1960.6 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on t
15、he ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users c
16、onsult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.2.1 DiscussionSince a given
17、beta-particle emitter may decay to several different quantum states of the product nucleus, more than one maximumenergy may be listed for a given radioactive species.3.1.3 counter backgroundin the measurement of radioactivity, the counting rate resulting from factors other than theradioactivity of t
18、he sample and reagents used.NOTE 2Counter background varies with the location, shielding of the detector, and the electronics; it includes cosmic rays, contaminatingradioactivity and electrical noise.3.1.3.1 DiscussionCounter background varies with the location, shielding of the detector, and the el
19、ectronics; it includes cosmic rays, contaminatingradioactivity and electrical noise.3.1.4 counter beta-particle effciencyin the measurement of radioactivity, that fraction of beta particles emitted by a sourcewhich is detected by the counter.3.1.5 counter effciencyin the measurement of radioactivity
20、, that fraction of the disintegrations occurring in a source which isdetected by the counter.3.1.6 radioactive homogeneous waterwater in which the radioactive material is uniformly dispersed throughout the volumeof water sample and remains so until the measurement is completed or until the sample is
21、 evaporated or precipitating reagents areadded to the sample.3.1.7 reagent backgroundin the measurement of radioactivity of water samples, the counting rate observed when a sample isreplaced by mock sample salts or by reagent chemicals used for chemical separations that contain no analyte.NOTE 3Reag
22、ent background varies with the reagent chemicals and analytical methods used and may vary with reagents from different manufacturersand from different processing lots.3.1.7.1 DiscussionReagent background varies with the reagent chemicals and analytical methods used and may vary with reagents from di
23、fferentmanufacturers and from different processing lots.3.2 DefinitionsFor terms not defined in this test method or in Terminology D1129, reference may be made to other publishedglossaries. glossaries.4. Summary of Test Method4.1 Beta radioactivity may be measured by one of several types of instrume
24、nts composed of a detecting device and combinedamplifier, power supply, and scalerthe most widely used being proportional or Geiger-Mller counters. Where a wide range ofcounting rates is encountered (0.1 to 1300 counts per seconds), the proportional-type counter is preferable due to a shorterresolvi
25、ng time and greater stability of the instrument. The test sample is reduced to the minimum weight of solid material havingmeasurable beta activity by precipitation, ion exchange resin, or evaporation techniques. Beta particles entering the sensitive regionof the detector produce ionization of the co
26、unting gas. The negative ion of the original ion pair is accelerated towards the anode,producing additional ionization of the counting gas and developing a voltage pulse at the anode. By use of suitable electronicapparatus, the pulse is amplified to a voltage sufficient for operation of the counter
27、scaler. The number of pulses per unit of timeis related to the disintegration rate of the test sample. The beta-particle efficiency of the system can be determined by use ofprepared standards having the same radionuclide composition as the test specimen and equivalent residual plated solids. Anarbit
28、rary efficiency factor can be defined in terms of some other standard such as cesium-137.5. Significance and Use5.1 This test method was developed for the purpose of measuring the gross beta radioactivity in water. It is used for the analysisof both process and environmental water to determine gross
29、 beta activity.6. Measurement Variables6.1 The relatively high absorption of beta particles in the sample media and any material interposed between source andsensitive volume of the counter results in an interplay of many variables which affect the counting rate of the measurement. Thus,for reliable
30、 relative measurements, hold all variables constant while counting all test samples and standards. For absolutemeasurements, appropriate correction factors are applied. The effects of geometry, backscatter radiation, source diameter,self-scatter and self-absorption, absorption in air and detector wi
31、ndow for external counters, and counting coincidence losses havebeen discussed discussed2, 3, 4, 5 and may be described by the following relation:D1890 152cps5BqbGp!fbs!faw!fd!fssa!fc! (1)where:cps = recorded counts per second corrected for background,Bqb = disintegrations per second yielding beta p
32、articles,Gp = point source geometry (defined by the solid angle subtended by the sensitive area of the detector),fbs = backscatter factor or ratio of cps with backing to cps without backing,faw = factor to correct for losses due to absorption in the air and window of external detectors. It is equal
33、to the ratio of theactual counting rate to that which would be obtained if there were no absorption by the air and window between thesource and sensitive volume of the detector. Expressed in terms of absorption coefficient and density of absorber,faw = e x, where = absorption coefficient, in square
34、centimetres per milligram, and x = absorber density in milligramsper square centimetre.fd = factor to correct a spread source counting rate to the counting rate of the same activity as a point source on the same axisof the system,fssa = factor to correct for the absorption and scatter of beta partic
35、les within the material accompanying the radioactive element,andfc = factor for coincident events to correct the counting rate for instrument resolving time losses and defined by the simplifiedequation, fc = 1 nr, where, n = the observed counts per second, and r = instrument resolving time in second
36、s. Generally,the sample size or source to detector distance is varied to obtain a counting rate that precludes coincident losses.Information on the effect of random disintegration and instrument resolving time on the sample count rate as well asmethods for determining the resolving time of the count
37、ing system may be found in the literature.For most applications, a detector system is calibrated using a single beta emitting radionuclide and an efficiency of detection,fo, response curve generated for various sample residue weights. The efficiency of detection for each sample residual weightincorp
38、orates all the factors mentioned above so that:fo 5cps/Bq5Gp!fbs!faw!fd!fssa!fc! (2)6.1.1 In tracer studies or tests requiring only relative measurements in which the data are expressed as being equivalent to adefined standard, the above correction factors can be simply combined into a counting effi
39、ciency factor. The use of a countingefficiency factor requires that sample mounting, density of mounting dish, weight of residue in milligrams per square centimetre,and radionuclide composition, in addition to conditions affecting the above described factors, remain constant throughout theduration o
40、f the test and that the comparative standard be prepared for counting in the same manner as the test samples. The datafrom comparative studies between independent laboratories, when not expressed in absolute units, are more meaningful whenexpressed as percentage relationships or as the equivalent of
41、 a defined standard. Expressing the data in either of these two waysminimizes the differences in counters and other equipment and in techniques used by the laboratories conducting the tests.6.2 The limit of sensitivity for both Geiger-Muller and proportional counters is a function of the background
42、counting rate.Massive shielding or anti-coincidence detectors and circuitry, or both, are generally used to reduce the background counting rateto increase the sensitivity.7. Interferences7.1 Material interposed between the test sample and the instrument detector, as well as increasing density in the
43、 samplecontaining the beta emitter, produces significant losses in sample counting rates. Liquid samples are evaporated to dryness in dishesthat allow the sample to be counted directly by the detector. Since the absorption of beta particles in the sample solids increaseswith increasing density and v
44、aries inversely with the maximum beta energy, plated solids shall remain constant between relatedtest samples and should duplicate 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 the degree of efficiency depe
45、ndentupon the type of detector. detector.2, 3, 4, 5 The effect of interfering radiations on the beta counting rate is more easily evaluatedwith external-type counters where appropriate absorbers can be used to evaluate the effects of interfering radiation.8. Apparatus8.1 Beta Particle Counter, consi
46、sting of the following components:8.1.1 DetectorThe end-window Geiger-Muller tube and the internal or external sample gas-flow proportional chambers arethe two most prevalent commercially available detector types. The material used in the construction of the detector should be freefrom detectable ra
47、dioactivity. When detectors contain windows, the manufacturer shall supply the window density expressed inmilligrams per square centimetre. To establish freedom from undesirable characteristics, the manufacturer shall supply voltageplateau and background counting rate data. Voltage plateau data shal
48、l show the threshold voltage, slope, and length of plateau.Detectors requiring external positioning of the test sample are mounted on a tube support of low-density material (aluminum orplastic) and positioned so the center of the window is directly above the center of the test sample.The distance be
49、tween the detectorwindow and test sample plays an important part in determining the geometry of the system and can be varied for external countersto correspond more favorably with such factors as activity level, source size, sensitivity requirements, energy of beta particles, etc.D1890 153A convenient arrangement is to combine the tube mount with a sample holder containing slots for positioning the sample at threeor four distances from the detector window, varying from approximately 5 to 100 mm from tube flange.8.1.2 Detector ShieldThe det
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