1、Designation: C 1415 01a (Reapproved 2007)Standard Test Method for238Pu Isotopic Abundance By Alpha Spectrometry1This standard is issued under the fixed designation C 1415; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 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 covers the use of alpha spectrometryfor determining the238Pu isotopic abundance in plutoniumsamples
3、. It is particularly useful for samples in which the238Pucontent is less than 1 % of the total plutonium content. For suchsamples, mass spectrometric results are less reliable than thosefrom alpha spectrometry because of interference from any238Uisobar remaining after ion exchange.1.2 This standard
4、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 applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM S
5、tandards:2C 697 Test Methods for Chemical, Mass Spectrometric, andSpectrochemical Analysis of Nuclear-Grade PlutoniumDioxide Powders and PelletsC 1168 Practice for Preparation and Dissolution of Pluto-nium Materials for AnalysisD 1193 Specification for Reagent Water3. Summary of Test Method3.1 This
6、determination method involves the measurement ofthe alpha-activity ratio of238Pu and239Pu +240Pu. The isotopicanalysis of plutonium for the238Pu isotope requires the priorseparation of interferences.After dissolution of the sample (seePractice C 1168), the plutonium is separated from interferencesby
7、 an anion-exchange purification technique. Nitric acid(HNO3) is used to adsorb the plutonium fraction on the resin.Interfering ions, principally uranium and americium, are notadsorbed. The plutonium is then eluted with dilute HNO3(0.1M). Because an alpha-activity ratio is used, quantitative recov-er
8、y of the plutonium is not required. The alpha spectrum in the5 to 6-MeV region is obtained. The total counts in the238Pu andthe239Pu +240Pu peaks are obtained and corrected for back-ground. The238Pu abundance is calculated from the ratio of thealpha activity due to238Pu and that due to239Pu +240Pu.
9、Theabundance of239Pu and240Pu is determined by mass spectrom-etry (see Test Methods C 697) on a separate portion of thepurified sample.4. Significance and Use4.1 This test method is used when the determined of238Puisotopic abundance is required for plutonium samples.5. Interferences241Am is always p
10、resent as a result of241Pu decay and is adirect interference that must be removed prior to the determi-nation of238Pu. The very small amount of230Th and232Thwhich could be present causes insignificant interference withthe determination of238Pu at the level of uncertainty of this testmethod. Other nu
11、clides that would interfere, suchas238U,243Am,245Cm, 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
12、 the alpha spectra, and, consequently,decrease the sensitivity of the test method.6. Apparatus6.1 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 acceptable.6.2 Alpha spectrometer. T
13、his instrument should typicallyconsist of the following components:6.2.1 Silicon surface barrier detector, with an active area ofat least 100 mm2, a depletion depth of greater than 100 m, anda resolution of 30 keV or less full width at half maximum(FWHM) (for241Am 5.486 MeV alpha).6.2.2 Evacuable, l
14、ight-tight chamber in which the detectorand the counting plate on its support can be mounted.6.2.3 Preamplifier (charge-sensitive field-effect transistor)with noise less than 4.6 keV when used with above detector(100 pF capacitance).1This test method is under the jurisdiction of ASTM Committee C26 o
15、n NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved Feb. 15, 2007. Published April 2007. Originallyapproved in 1999. Last previous edition approved in 2001 as C 1415 01a.2For referenced ASTM standards, visit the ASTM website, www.ast
16、m.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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2.4 Det
17、ector bias supply, 0 to 150 V, continuously vari-able, well-regulated and stable, with noise and ripple less than0.0002 %.6.2.5 Main spectroscopy amplifier, low noise, with variableshaping constants and baseline restoration.6.2.6 Biased amplifier and pulse stretcher, with continu-ously adjustable po
18、st-gain and automatic pile-up rejection.6.2.7 Multichannel pulse-height analyzer. A multichannelanalyzer is most versatile and convenient, since is can be usedfor the acquisition of data from one to four detectors, simul-taneously. Even if only one detector is used, such an analyzerhas the advantage
19、s 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 perform electronic integration is espe-cially conveni
20、ent. 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.6.2.8 A computer printer for output printing of the datafrom the multichannel analyzer (optional).6.3 Heat lamp.6.4 Bunsen burner.6.5 Sample beaker, 30-mL, bo
21、rosilicate glass.6.6 Bottles or vials.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals are usedin all tests and conform to the specifications of the Committeeon Analytical Reagents of the American Chemical Society.37.2 Purity of Water Unless otherwise indicated, refer-ences to
22、water shall be understood to mean distilled ordeionized water (Specification D 1193).7.3 Nitric acid (HNO3). Concentrated (sp gr 1.42).7.4 Nitric acid, 4 M. Add 250 mL of nitric acid (sp gr 1.42)to 750 mL of water and dilute to 1 L.7.5 Nitric acid, 0.1 M.Add 6.2 mL of nitric acid (sp gr 1.42)to 950
23、mL of water and dilute to 1 L.7.6 Anion-exchange resin and column,4100-200 mesh,containing quaternary ammonium function groups.8. Calibration of the Alpha Spectrometer8.1 Initial AlignmentSet the amplifier so that channel zerois about 4.75 MeV. Use a standard alpha source such as the5.30 MeV particl
24、e of210Po, or the 5.49 MeV particle of241Am,for calibration. Establish the system gain at some convenientvalue, such as 5 keV per channel.8.2 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 FWHM
25、up to 50keV can be tolerated.8.3 BackgroundObtain a background spectrum with aclean counting disk in the chamber.8.4 Frequency of CalibrationThe system gain and reso-lution should be checked periodically, to maintain the sameoperating conditions and to check whether the spectrometer hasdeteriorated.
26、 Daily background counting is advisable, to ensurethat neither the chamber nor the detector has been contami-nated.9. Procedure9.1 Transfer an aliquot of approximately 1 mg Pu from asample obtained from Practice C 1168 or equivalent procedureinto a 30-mL beaker and take to dryness on a hot plate.9.2
27、 Add 3-4 mL of 4 M HNO3and take to dryness on a hotplate. Cool to room temperature. Repeat this process two moretimes.9.3 Add 15 mL of 4 M HNO3to an anion-exchange columnto precondition it.9.4 Dissolve the sample with 2-3 mL 4 M HNO3andtransfer it to the preconditioned anion-exchange column. Letthe
28、effluent drain into another beaker; the effluent will bediscarded according to the disposal requirements of the specificsite.9.5 Rinse the sample beaker with 2-3 mL of 4 M HNO3andtransfer the rinse to the column; allow the rinsate to drain.Repeat this rinse step once more.9.6 Add 5 mL of 4 M HNO3to
29、wash the column and allowthe column to drain. This waste will be added to the wastealready accumulated in 9.4 and 9.5. Repeat this wash step threemore times.9.7 Place a clean bottle or vial under the column and elutethe plutonium from the column with two 5mL portions of 0.1M HNO3. The eluant will be
30、 used for both alpha and massspectrometry.9.8 Mix eluant and transfer a 10 L aliquot of this solutionto a counting disk. Dry under a heat lamp.9.9 Fire the disk by slowly heating it to dull redness in aBunsen burner.9.10 Place the counting disk in a chamber of the alphaspectrometer and evacuate the
31、chamber. Count until sufficientcounts are accumulated for desired precision.9.11 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 the netcounts, subtract the background counts in the same chan
32、nels,adjusted for the same counting time, from the total counts inthe peaks, to obtain the net counts.9.12 Using the aliquot from the purified sample obtained in9.7, perform mass spectrometric analysisfor239Pu,240Pu,241Pu, and242Pu in accordance with TestMethods C 697, Sections 139-147.10. Calculati
33、on10.1 Calculate the weight percent of238Pu as follows:W85C8W9A91 W0A0!A8C9(1)3Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical society, see Analar Standards for Labor
34、atoryChemicals, BDH Ltd. Poole, Dorset, U.K., and the United States Pharmacopeia andNational Formulary, U.S. Pharmaceutical 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.C 1415 01a (200
35、7)2where:W8= weight percent of238Pu,W9= weight percent of239Pu from mass spectrometry(normalized),W0= weight percent of240Pu from mass spectrometry(normalized),A8= alpha specific activity of238Pu,A9= alpha specific activity of239Pu,A0= alpha specific activity of240Pu,C8= observed counts in238Pu peak
36、s, andC9= observed counts in239Pu peaks +240Pu peaks.10.2 The specific activity of a nuclide (in disintegrations perminute per microgram) is calculated from its half-life by theformula:Specific activity, d/min/g 57.937 3 1011Awt1/2(2)where:Aw= atomic weight of the nuclide, andt1/2= half-life years,
37、(see Table 1fvariant5).11. Precision and Bias11.1 New Brunswick Laboratory Certified 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 collect
38、ed in the238Pu alpha peak. Thepercent relative difference from the reference value (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
39、 the other 35 values). All results werecalculated both with and without the suspected 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 (
40、1.94) which, in the absence of statisticallysignificant sources of variation, serves 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 preci
41、sion without the outlier of 2.00 which includesa component due to day-to-day variation.11.2 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
42、.006 weight percent, or2.4 % of the value.12. Keywords12.1 alpha spectrometry; ion exchange; plutonium238abundanceASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly adv
43、ised 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 time by the responsible technical committee and must be reviewed every five years andif not revised, either
44、 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. I
45、f 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 below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Indivi
46、dual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).5The constants in Table 1 were used in the calculation of the measu
47、red 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 taken should be stated.6Statistical Methods for Nuclear Material Management , W. Michael Bowen andCarl
48、A. Bennett, Eds., NUREG/CR-4604, PNL-5849 (US Nuclear RegulatoryCommission, Washington, DC, 1988), pp. 265269.TABLE 1 Principal Alpha Peaks of InterestANuclide t1/2, years Alpha-ParticleEnergy, MeVAlpha-ParticleAbundances, %238Pu 87.7 6 0.3 5.50 70.95.46 29.0239Pu 24,110 6 30 5.16 73.35.14 15.15.10 11.5240Pu 6563 6 7 5.17 72.85.12 27.1241Am 432.2 6 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.C 1415 01a (2007)3
