1、Designation: C1415 14Standard Test Method for238Pu Isotopic Abundance By Alpha Spectrometry1This standard is issued under the fixed designation C1415; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A num
2、ber 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 covers the use of alpha spectrometryfor determining the238Pu isotopic abundance in plutoniumsamples. It is particularly u
3、seful for samples in which the238Pucontent is less than 1 % of the total plutonium content. For suchsamples, mass spectrometric results are vulnerable to biasbecause of potential interference from any238U isobar remain-ing after ion exchange.1.2 The values stated in SI units are to be regarded as th
4、estandard. The values given in parentheses are for informationonly.1.3 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 safety and health practices and determine the ap
5、plica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C697 Test Methods for Chemical, Mass Spectrometric, andSpectrochemical Analysis of Nuclear-Grade PlutoniumDioxide Powders and PelletsC859 Terminology Relating to Nuclear MaterialsC1168 Practice for Prepara
6、tion and Dissolution of PlutoniumMaterials for AnalysisC1625 Test Method for Uranium and Plutonium Concentra-tions and Isotopic Abundances by Thermal IonizationMass SpectrometryC1672 Test Method for Determination of Uranium or Pluto-nium Isotopic Composition or Concentration by the TotalEvaporation
7、Method Using a Thermal Ionization MassSpectrometerD1193 Specification for Reagent Water3. Terminology3.1 For definitions of pertinent terms not listed here, seeTerminology C859.4. Summary of Test Method4.1 This determination method involves the measurement ofthe alpha-activity ratio of238Pu and239Pu
8、 +240Pu. Theisotopic analysis of plutonium for the238Pu isotope requiresthe prior separation of potentially interfering species. Afterdissolution of the sample (see Practice C1168), the plutoniumis separated from interferences by an anion-exchange purifica-tion technique. Nitric acid (HNO3) is used
9、to adsorb theplutonium fraction on the resin. Interfering ions, principallyuranium and americium, are not adsorbed. The plutonium isthen eluted with dilute HNO3(0.1 M). Because an alpha-activity ratio is used, quantitative recovery of the plutonium isnot required. The alpha spectrum in the 5 to 6-Me
10、V region isobtained. The total counts in the238Pu and the239Pu +240Pupeaks are obtained and corrected for background. The238Puabundance is calculated from the ratio of the alpha activity dueto238Pu and that due to239Pu +240Pu. The abundance of239Puand240Pu is determined by mass spectrometry (see Tes
11、tMethods C697, C1625,orC1672) on a separate portion of thepurified sample.5. Significance and Use5.1 This test method is used when the determination of238Pu isotopic abundance is required for plutonium samples.6. Interferences6.1 Am-241 is always present as a result of241Pu decay andis a direct inte
12、rference that must be removed prior to thedetermination of238Pu. The very small amount of230Th and232Th which could be present causes insignificant interferencewith the determination of238Pu at the level of uncertainty ofthis test method. Other nuclides that could interfere, such as238U,243Am,245Cm,
13、 and249Bk, are removed by the anion-exchange separation. Any residual uranium, while it does notdirectly interfere with the alpha-pulse height determination,can raise the salt content of the sample. A high salt content candecrease the resolution of the alpha spectra, and, consequently,decrease the a
14、ccuracy of the test method.1This test method is under the jurisdiction of ASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved June 1, 2014. Published July 2014. Originally approvedin 1999. Last previous edition ap
15、proved in 2007 as C1415 01a (2007). DOI:10.1520/C1415-14.2For 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.Copy
16、right ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17. Apparatus7.1 Counting disks of polished platinum, tantalum, or stain-less steel, sized to fit the detection chamber. A disk 25 mm indiameter and 0.5 mm thick has been found to be acceptab
17、le.7.2 Alpha spectrometer. This instrument may consist of thefollowing individual components but more typically as anintegrated system that is readily interfaced to a computer:7.2.1 Silicon surface barrier detector, with an active area ofat least 100 mm2, a depletion depth of greater than 100 m, and
18、a resolution of 30 keV or less full width at half maximum(FWHM) (for241Am 5.486 MeV alpha).7.2.2 Evacuable, light-tight chamber in which the detectorand the counting plate on its support can be mounted.7.2.3 Preamplifier (charge-sensitive field-effect transistor)with noise less than 4.6 keV when use
19、d with above detector(100 pF capacitance).7.2.4 Detector bias supply, 0 to 150 V, continuouslyvariable, well-regulated and stable, with noise and ripple lessthan 0.0002 %.7.2.5 Main spectroscopy amplifier, low noise, with variableshaping constants and baseline restoration.7.2.6 Biased amplifier and
20、pulse stretcher, with continu-ously adjustable post-gain and automatic pile-up rejection.7.2.7 Multichannel pulse-height analyzer. A multichannelanalyzer is most versatile and convenient, since it can be usedfor the acquisition of data from one to four detectors, simul-taneously. Even if only one de
21、tector is used, such an analyzerhas the advantages that background may be stored in anothersubgroup and subtracted electronically from the spectrum ofinterest, and that several spectra can be stored and compared.An analyzer that permits the analyst to set windows around thepeaks of interest and perf
22、orm electronic integration is espe-cially convenient. The analyzer should accept pulses 0 to 10 Vand 3 to 6 s in width and should have a capacity of at least 106counts full scale per channel.7.3 Heat lamp.7.4 Bunsen burner, or similar heat source device.7.5 Sample beaker, 30-mL, borosilicate glass.7
23、.6 Bottles or vials.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals are usedin all tests and conform to the specifications of the Committeeon Analytical Reagents of the American Chemical Society.38.2 Purity of WaterUnless otherwise indicated, referencesto water shall be unders
24、tood to mean distilled or deionizedwater (Specification D1193).8.3 Nitric acid (HNO3). Concentrated (sp gr 1.42).8.4 Nitric acid, 4 M. Add 250 mL of nitric acid (sp gr 1.42)to 750 mL of water and dilute to 1 L.8.5 Nitric acid, 0.1 M. Add 6.2 mL of nitric acid (sp gr 1.42)to 950 mL of water and dilut
25、e to 1 L.8.6 Anion-exchange resin and column,4100-200 mesh, con-taining quaternary ammonium functional groups.9. Calibration of the Alpha Spectrometer9.1 Initial CalibrationSet the amplifier so that channelzero is about 4.75 MeV. Use a standard alpha source such asthe 5.30 MeV particle of210Po, or t
26、he 5.49 MeV particle of241Am, for energy calibration. Establish the system gain atsome convenient value that will cover the needed energy range.9.2 ResolutionCount the standard source and determinethe energy span at half the peak height. A full width halfmaximum of 30 keV or less is desirable, but a
27、 FWHM up to 50keV can be tolerated.9.3 BackgroundObtain a background spectrum with aclean counting disk in the chamber.9.4 Frequency of CalibrationThe energy calibration andenergy resolution should be checked periodically, to maintainthe same operating conditions and to check whether thespectrometer
28、 has deteriorated. Daily or similarly frequentbackground counting is advisable, to ensure that neither thechamber nor the detector has been overly contaminated andthat an appropriate background correction is accomplished.10. Procedure10.1 Transfer an aliquot of approximately 1 mg Pu from asample obt
29、ained from Practice C1168 or equivalent procedureinto a 30-mL beaker and take to dryness on a hot plate.10.2 Add 3-4 mL of 4 M HNO3and take to dryness on a hotplate. Cool to room temperature. Repeat this process two moretimes.10.3 Add 15 mLof 4 M HNO3to an anion-exchange columnto precondition it.10.
30、4 Dissolve the sample with 2-3 mL 4 M HNO3andtransfer it to the preconditioned anion-exchange column. Letthe effluent drain into another beaker; the effluent will bediscarded according to the disposal requirements of the specificsite.10.5 Rinse the sample beaker with 2-3 mLof 4 M HNO3andtransfer the
31、 rinse to the column; allow the rinsate to drain.Repeat this rinse step once more.10.6 Add 5 mL of 4 M HNO3to wash the column and allowthe column to drain. This waste will be added to the wastealready accumulated in 10.4 and 10.5. Repeat this wash stepthree more times.10.7 Place a clean bottle or vi
32、al under the column and elutethe plutonium from the column with two 5mL portions of 0.1M HNO3. The eluant will be used for both alpha and massspectrometry.10.8 Mix eluant and transfer a 10 L aliquot of this solutionto a counting disk. Dry under a heat lamp.3Reagent Chemicals, American Chemical Socie
33、ty Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical society, see Analar Standards for LaboratoryChemicals, BDH Ltd. Poole, Dorset, U.K., and the United States Pharmacopeia andNational Formulary, U.S. Pharmacopeial
34、 Convention, Inc. (USPC), Rockville, MD.4Disposable, prefilled columns packed with AG 1-X 8, available from Bio-Rad,Richmond, CA, have been found to be acceptable.C1415 14210.9 Fire the disk by slowly heating it to dull redness in aBunsen burner or similar heat source device.10.10 Place the counting
35、 disk in a chamber of the alphaspectrometer and evacuate the chamber. Count until sufficientcounts are accumulated for desired precision.10.11 Obtain the total count for a sufficient number ofchannels to include the238Pu peaks (5.50 + 5.46 MeV) andthe239Pu +240Pu peaks (5.10 to 5.17 MeV). To obtain
36、the netcounts, subtract the background counts in the same channels,adjusted for the same counting time, from the total counts inthe peaks, to obtain the net counts.10.12 Using the aliquot from the purified sample obtained in10.7, perform mass spectrometric analysis for239Pu,240Pu,241Pu, and242Pu in
37、accordance with Test Methods C697(Sections 97105), C1625,orC1672.11. Calculation11.1 Calculate the weight percent of238Pu as follows:W85C8W9A91W0A0!A8C9(1)where:W8= weight percent of238Pu,W9= weight percent of239Pu from mass spectrometry(normalized),W0= weight percent of240Pu from mass spectrometry(
38、normalized),A8= alpha specific activity of238Pu,A9= alpha specific activity of239Pu,A0= alpha specific activity of240Pu,C8= observed net counts in238Pu peaks, andC9= observed net counts in239Pu peaks +240Pu peaks.11.2 The specific activity of a nuclide (in disintegrations perminute per microgram) is
39、 calculated from its half-life by theformula:Specific activity, d/min/g 57.937 31011Awt1/2(2)where:Aw= atomic weight of the nuclide, andt12 = half-life years, (see Table 15).TABLE 1 Principal Alpha Peaks of InterestANuclide t12, years Alpha-ParticleEnergy, MeVAlpha-ParticleAbundances, %238Pu 87.7 0.
40、3 5.50 70.95.46 29.0239Pu 24,110 30 5.16 73.35.14 15.15.10 11.5240Pu 6563 7 5.17 72.85.12 27.1241Am 432.2 0.7 5.49 85.35.44 13.05.39 1.6AData taken from S.Y.F. Chu, L.P. Ekstrom, and R.B. Firestone, The Lund/LBNLNuclear Data Search, April 1998.12. Precision and Bias12.1 New Brunswick Laboratory Cert
41、ified Reference Mate-rial 137, Plutonium Isotopic Standard, was measured for238Pucontent 36 times by one analyst on 6 different days over aperiod of 10 months. For each measurement, approximately10 000 counts were collected in the238Pu alpha peak. Thepercent relative difference from the reference va
42、lue (defined as(observed value - reference value)/reference value (100), wascalculated for each determination. One determinations valuewas an apparent statistical outlier (its magnitude was over 4times greater than any of the other 35 values). All results werecalculated both with and without the sus
43、pected outlier (resultswithout the value are indicated by parenthesis). The meanpercent relative difference of the data is 1.26 (0.64) whichserves as an estimate of bias. The simple standard deviation ofthe data is 4.18 (1.94) which, in the absence of statisticallysignificant sources of variation, s
44、erves as an estimate ofprecision. Removing the suspect data point from calculationshowever, gives a statistically significant day-to-day variation inthe data. Variance component techniques6give an overallestimate of precision without the outlier of 2.00 which includesa component due to day-to-day va
45、riation.12.2 At the time of analysis, the238Pu content of CRM 137constituted 0.25 weight percent of the total plutonium content,with an uncertainty (95 % confidence interval for a singledetermination) on that content of 0.006 weight percent, or2.4 % of the value.13. Keywords13.1 alpha spectrometry;
46、ion exchange; plutonium238abundance5The constants in Table 1 were used in the calculation of the measured valuesused to determine precision and bias of the method. Other compilations of theseconstants may be used as agreed upon between shipper and receiver. The databasefrom which the constants are t
47、aken should be stated.6Statistical Methods for Nuclear Material Management, W. Michael Bowen andCarl A. Bennett, Eds., NUREG/CR-4604, PNL-5849 (US Nuclear RegulatoryCommission, Washington, DC, 1988), pp. 265269.C1415 143ASTM International takes no position respecting the validity of any patent right
48、s asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any t
49、ime by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown be
