ASTM C1415-2018 Standard Test Method for 238Pu Isotopic Abundance By Alpha Spectrometry.pdf

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1、Designation: C1415 14C1415 18Standard 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 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.1. Scope1.1 This test method covers the use of alpha spectrometry for determining the 238Pu isotopic abundance in plutonium samples.It is part

3、icularly useful for samples in which the 238Pu content is less than 1 % of the total plutonium content. For such samples,mass spectrometric results are vulnerable to bias because of potential interference from any 238U isobar remaining after ionexchange.1.2 The values stated in SI units are to be re

4、garded as the standard. The values given in parentheses are for information only.1.3 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 to establish appropriate safety safety, health, and healthe

5、nvironmental practices and determine theapplicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standar

6、ds, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C697 Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Plutonium DioxidePowders and PelletsC859 Termi

7、nology Relating to Nuclear MaterialsC1168 Practice for Preparation and Dissolution of Plutonium Materials for AnalysisC1411 Practice for The Ion Exchange Separation of Uranium and Plutonium Prior to Isotopic AnalysisC1625 Test Method for Uranium and Plutonium Concentrations and Isotopic Abundances b

8、y Thermal Ionization MassSpectrometryC1672 Test Method for Determination of Uranium or Plutonium Isotopic Composition or Concentration by the TotalEvaporation Method Using a Thermal Ionization Mass SpectrometerC1816 Practice for The Ion Exchange Separation of Small Volume Samples Containing Uranium,

9、 Americium, and PlutoniumPrior to Isotopic Abundance and Content AnalysisD1193 Specification for Reagent Water3. Terminology3.1 For Except as otherwise defined herein, definitions of pertinent terms not listed here, seeterms are as given in TerminologyC859.4. Summary of Test Method4.1 This determina

10、tion method involves the measurement of the alpha-activity ratio of 238Pu and 239Pu + 240Pu. The isotopicanalysis of plutonium for the 238Pu isotope requires the prior separation of potentially interfering species. After dissolution of thesample (see Practice C1168), the plutonium is separated from

11、interferences by purification techniques such as given in this testmethod or in Practices C1411 or C1816.1 This test method is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.Current edition approved June 1

12、, 2014June 1, 2018. Published July 2014July 2018. Originally approved in 1999. Last previous edition approved in 20072014 asC1415 01a (2007).C1415 14. DOI: 10.1520/C1415-14.10.1520/C1415-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at servic

13、eastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the 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. Be

14、causeit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult 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

15、 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.2 In this test method, nitric acid (HNO3) is used to adsorb the plutonium fraction on the resin. Interfering ions, principallyuranium and americium, are not adsorbed. The plutonium is then eluted with dilute HNO3 (0.1

16、 M).4.3 This determination method involves the measurement of the alpha-activity ratio of 238Pu and 239 Pu + 240Pu. The isotopicanalysis of plutonium for the 238Pu isotope requires the prior separation of potentially interfering species. After dissolution of thesample (see Practice C1168), the pluto

17、nium is separated from interferences by an anion-exchange purification technique. Nitricacid (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 (0.1 M). Because an alpha-act

18、ivity ratio is used, quantitative recoveryof the plutonium is not required. The alpha spectrum in the 5 to 6-MeV region is obtained. The total counts in the 238Pu and the239Pu + 240Pu peaks are obtained and corrected for background. The 238Pu abundance is calculated from the ratio of the alphaactivi

19、ty due to 238Pu and that due to 239Pu + 240Pu. The abundance of 239Pu and 240Pu is determined by mass spectrometry (seeTest Methods C697, C1625, or C1672) on a separate portion of the purified sample.5. Significance and Use5.1 This test method is used when the determination of 238Pu isotopic abundan

20、ce is required for plutonium samples.6. Interferences6.1 Am-241 is always present as a result of 241Pu decay and is a direct interference that must be removed prior to thedetermination of 238Pu. The very small amount of 230Th and 232Th which could be present causes insignificant interference withthe

21、 determination of 238Pu at the level of uncertainty of this test method. Other nuclides that could interfere, such as 238U, 243Am,245Cm, and 249Bk, are removed by the anion-exchange separation. purification prior to analysis. Any residual uranium, while itdoes not directly interfere with the alpha-p

22、ulse height determination, can raise the salt content of the sample. A high salt contentcan decrease the resolution of the alpha spectra, and, consequently, decrease the accuracy of the test method.7. Apparatus7.1 Counting disks of polished platinum, tantalum, or stainless steel, sized to fit the de

23、tection chamber. A disk 25 mm indiameter and 0.5 mm thick has been found to be acceptable.7.2 Alpha spectrometer. This instrument may consist of the following individual components but more typically as an integratedsystem that is readily interfaced to a computer:7.2.1 Silicon surface barrierbased a

24、lpha detector, with an active area of at least 100 mm2, a depletion depth of greater than 100m,100 m or more, and a resolution of 3050 keV or less full width at half maximum (FWHM) (for 241Am 5.486 MeV alpha).NOTE 1A FWHM of 30 keV or less is desirable, but a FWHM up to 50 keV can be tolerated.7.2.2

25、 Evacuable, light-tight chamber in which the detector and 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 used with above detector (100 pFcapacitance).7.2.4 Detector bias supply, 0 to 150 V, continuously

26、 variable, well-regulated and stable, with noise and ripple less than0.0002 %.7.2.5 Main spectroscopy amplifier, low noise, with variable shaping constants and baseline restoration.7.2.6 Biased amplifier and pulse stretcher, with continuously adjustable post-gain and automatic pile-up rejection.7.2.

27、7 Multichannel pulse-height analyzer. A A multichannel analyzer is most versatile and convenient, since it can be used forthe acquisition of data from one to four detectors, simultaneously. Even if only one detector is used, such an analyzer has theadvantages that background may be stored in another

28、 subgroup and subtracted electronically from the spectrum of interest, andthat several spectra can be stored and compared. An analyzer that permits the analyst to set windows around the peaks of interestand perform electronic integration is especially convenient. The analyzer should accept pulses 0

29、to 10 V and 3 to 6 s in widthand should have a capacity of at least 106 counts 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.7.6 Bottles or vials.7.7 Hot plate.C1415 1828. Reagents and Materials8.1 Purity of Reagent

30、sReagent grade chemicals are used in all tests and conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society.38.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean distilled or deionized water(Specification in confo

31、rmance with Specification D1193). , Type I.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 dilute to 1 L.8.6 Anion

32、-exchange resin and column, 100-200 mesh, 74-149 m (100-200 mesh) dry size, containing quaternary ammoniumfunctional groups.9. Calibration of the Alpha Spectrometer9.1 Initial CalibrationSet the amplifier so that channel zero is about 4.75 MeV. Use a standard alpha source such as the 5.30MeV particl

33、e of 210Po, or the 5.49 MeV particle of 241Am, for energy calibration. Establish the system gain at some convenientvalue that will cover the needed energy range.9.2 ResolutionCount the standard source and determine the energy span at half the peak height. A full width half maximumof 30 keV or less i

34、s desirable, but a FWHM up to 50 keV can be tolerated.9.3 BackgroundObtain a background spectrum with a clean counting disk in the chamber.9.4 Frequency of CalibrationThe energy calibration and energy resolution should be checked periodically, to maintain thesame operating conditions and to check wh

35、ether the spectrometer has deteriorated. Daily or similarly frequent background countingis advisable, to ensure that neither the chamber nor the detector has been overly contaminated and that an appropriate backgroundcorrection is accomplished.10. ProcedureNOTE 2Procedure steps 10.2 through 10.7 wer

36、e developed based on pre-packed columns containing 2 mLof Bio-RadAG 1-X8 anion exchange resin.Other resins with similar characteristics (for example, those with quaternary ammonium functional groups and a high degree of crosslinkage) can be used.Adjustments in acid concentration, or volume, or both,

37、 as described in these steps may be required.NOTE 3Purification as described in Practices C1411 or C1816 or using extraction chromatography resins may be used as an alternative to steps 10.1through 10.7 for separation of plutonium from uranium and other impurities prior to alpha spectrometry.10.1 Tr

38、ansfer an aliquot of approximately 1 mg Pu from a sample obtained from Practice C1168 or equivalent procedure intoa 30-mL beaker and take to dryness on a hot plate.10.2 Add 3-4 mL of 4 M HNO3 and take to dryness on a hot plate. Cool to room temperature. Repeat this process two moretimes.10.3 Add 15

39、mL of 4 M HNO3 to an anion-exchange column to precondition it.10.4 Dissolve the sample with 2-3 mL 4 M HNO3 and transfer it to the preconditioned anion-exchange column. Let the effluentdrain into another beaker; the effluent will be discarded according to the disposal requirements of the specific si

40、te.10.5 Rinse the sample beaker with 2-3 mL of 4 M HNO3 and transfer the rinse to the column; allow the rinsate to drain. Repeatthis rinse step once more.10.6 Add 5 mL of 4 M HNO3 to wash the column and allow the column to drain. This waste will be added to the waste alreadyaccumulated in 10.4 and 1

41、0.5. Repeat this wash step three more times.NOTE 4If U or Am, or both, were present in the sample, they will also be present in this waste stream.10.7 Place a clean bottle or vial under the column and elute the plutonium from the column with two 5mL portions of 0.1 MHNO3. The eluant will be used for

42、 both alpha and mass spectrometry.10.8 Mix eluant and transfer a 10 L aliquot of this solution to a counting disk. Dry under a heat lamp.10.9 Fire the disk by slowly heating it to dull redness in a Bunsen burner or similar heat source device.10.10 Place the counting disk in a chamber of the alpha sp

43、ectrometer and evacuate the chamber. Count until sufficient countsare accumulated for desired precision.3 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical society, see

44、 Analar Standards for Laboratory Chemicals, BDH Ltd. Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.C1415 18310.11 Obtain the total count for a sufficient number of channels to include the 238Pu peaks (5.50 +an

45、d 5.46 MeV) andthe 239Pu +and 240Pu peaks (5.10 to (between 5.10 and 5.17 MeV). To obtain the net counts, subtract the background counts inthe same channels, adjusted for the same counting time, from the total counts in the peaks, to obtain the net counts.10.12 Using the aliquot from the purified sa

46、mple obtained in 10.7, perform mass spectrometric analysis for 239Pu, 240Pu, 241Pu,and 242Pu in accordance with Test Methods C697 (Sections 97105),8896), C1625, or C1672.11. Calculation11.1 Calculate the weight percent of 238Pu as follows:W8 5 C8 W9A9 1W0A0!A8C9(1)where:W8 = weight percent of 238Pu,

47、W9 = weight percent of 239Pu from mass spectrometry (normalized),W0 = weight percent of 240Pu from mass spectrometry (normalized),A8 = alpha specific activity of 238Pu,A9 = alpha specific activity of 239Pu,A0 = alpha specific activity of 240Pu,C8 = observed net counts in 238Pu peaks, andC9 = observe

48、d net counts in 239Pu peaks + 240Pu peaks.The reported result should also be accompanied by an estimate of uncertainty as required by the data use.11.2 The specific activity of a nuclide (in disintegrations per minute per microgram) is calculated from its half-life by theformula:Specific activity,d/

49、min/g5 7.93731011Aw t1/2 (2)where:Aw = atomic weight of the nuclide, andt12 = half-life years, (see Table 14).TABLE 1 Principal Alpha Peaks of InterestANuclide t12, years Alpha-ParticleEnergy, MeVAlpha-ParticleAbundances, %238Pu 87.7 0.3 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 1.6A Data taken from S.Y.F. Chu, L.P. Ekstrom, and R.B. Firestone, The Lund/LBNL Nuclear Data Search, April 1998.12. Precision and Bias12.1 New Brunswick Laboratory Certified Reference