ASTM C1871-2018a Standard Test Method for Determination of Uranium Isotopic Composition by the Double Spike Method Using a Thermal Ionization Mass Spectrometer.pdf

1、Designation: C1871 18C1871 18aStandard Test Method forDetermination of Uranium Isotopic Composition by theDouble Spike Method Using a Thermal Ionization MassSpectrometer1This standard is issued under the fixed designation C1871; the number immediately following the designation indicates the year ofo

2、riginal adoption or, in the case of revision, the year of last revision. 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 describes the determination of the isotope

3、amount ratios of uranium material as nitrate solutions by thedouble spike (DS) method using a thermal ionization mass spectrometer (TIMS) instrument.1.2 The analytical performance in the determination of the 235U/238U major isotope amount ratio by the DS method is five toten times better in terms of

4、 the internal and external reproducibility compared to the (“classical”) total evaporation (TE) methodas described in Test Method C1672 and the “modified total evaporation” (MTE) as described in Test Method C1832. This is dueto the use of an internal rather than external mass fractionation correctio

5、n by using a double spike material with a known orcertified 233U/236U isotope ratio, which is mixed with the sample prior to the measurement, either during the sample preparationor directly on the TIMS filament.1.3 The DS method cannot be applied for the determination of the 236U/238U minor isotope

6、amount ratio, and is also notrecommended for the determination of the 234U/238U minor isotope amount ratio.1.4 In case the uranium amount concentration of the double spike is known or certified, the uranium amount concentration ofthe sample can be determined using the isotope dilution mass spectrome

7、try (IDMS) method as described in Test Method C1672,by blending the sample gravimetrically with the double spike and performing a DS measurement.1.5 An external mass fractionation correction by measurements of a certified reference material loaded on different filamentsand measured in the same measu

8、rement sequence, as recommended for TE and required for MTE measurements, is not necessaryfor the DS method. However, for quality control (QC) purposes it is recommended to perform DS measurements of low enrichedor natural uranium isotopic reference materials on a regular basis.1.6 The DS method can

9、 only be applied to uranium samples with relative isotope abundances 233U/U and 236U/U below 105,the DS method is therefore mainly used for low enriched or close to natural uranium samples.1.7 UnitsThe values stated in SI units are to be regarded as the standard. When no SI units are provided, the v

10、alues are forinformation only.1.8 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, health, and environmental practices and determine the applicability ofregulat

11、ory limitations prior to use.1.9 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organiza

12、tion Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C753 Specification for Nuclear-Grade, Sinterable Uranium Dioxide PowderC776 Specification for Sintered Uranium Dioxide Pellets for Light Water ReactorsC787 Specification for Uranium Hexafluoride for Enrichmen

13、t1 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 Feb. 1, 2018June 1, 2018. Published February 2018July 2018. Originally approved in 2018. Last previous edition

14、 approved in 2018 asC1871 18. DOI: 10.1520/C1871-18.10.1520/C1871-18A.2 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 the ASTM

15、 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 consult

16、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 States1C833 Specification for Sintered (Uraniu

17、m-Plutonium) Dioxide Pellets for Light Water ReactorsC859 Terminology Relating to Nuclear MaterialsC967 Specification for Uranium Ore ConcentrateC996 Specification for Uranium Hexafluoride Enriched to Less Than 5 % 235UC1008 Specification for Sintered (Uranium-Plutonium) DioxidePelletsFast Reactor F

18、uel (Withdrawn 2014)3C1068 Guide for Qualification of Measurement Methods by a Laboratory Within the Nuclear IndustryC1128 Guide for Preparation of Working Reference Materials for Use in Analysis of Nuclear Fuel Cycle MaterialsC1156 Guide for Establishing Calibration for a Measurement Method Used to

19、 Analyze Nuclear Fuel Cycle MaterialsC1347 Practice for Preparation and Dissolution of Uranium Materials for AnalysisC1411 Practice for The Ion Exchange Separation of Uranium and Plutonium Prior to Isotopic AnalysisC1672 Test Method for Determination of Uranium or Plutonium Isotopic Composition or C

20、oncentration by the TotalEvaporation Method Using a Thermal Ionization Mass SpectrometerC1832 Test Method for Determination of Uranium Isotopic Composition by the Modified Total Evaporation (MTE) MethodUsing a Thermal Ionization Mass SpectrometerD1193 Specification for Reagent WaterE2586 Practice fo

21、r Calculating and Using Basic StatisticsE2655 Guide for Reporting Uncertainty of Test Results and Use of the Term Measurement Uncertainty in ASTM Test Methods3. Terminology3.1 Terminology C859 contains terms, definitions, descriptions of terms, nomenclature, and explanations of acronyms andsymbols s

22、pecifically associated with standards under the jurisdiction of Committee C26 on Nuclear Fuel Cycle.3.2 Definitions:3.2.1 abundance sensitivity, nin isotope amount ratio measurements, the ratio of the measured intensity of an ion beam at amass, m, to the measured intensity from the same isotope meas

23、ured at one mass unit difference (for example, m 6 1).3.2.1.1 DiscussionAbundance sensitivity is a measure of the magnitude of the peak tailing correction. For measuring uranium on thermal ionizationmass spectrometer (TIMS) and inductively coupled plasma mass spectrometry (ICP-MS) instruments, the a

24、bundance sensitivityis typically calculated as the ratio of the measured signal intensities at masses 237 and 238 using a suitable uranium sample.3.2.2 modified total evaporation, MTE, nanalytical method for determination of isotope amount ratios of uranium, asdescribed in Test Method C1832.3.2.3 to

25、tal evaporation, TE, nanalytical method for determination of isotope amount ratios of uranium or plutonium, asdescribed in Test Method C1672, also called “classical” total evaporation in this test method.3.2.4 turret, nholder for sample filaments.3.2.4.1 DiscussionAlternate names for turret are caro

26、usel, magazine, and wheel.3.3 Acronyms:3.3.1 CRMcertified reference material3.3.2 DSdouble spike3.3.3 DUdepleted uranium3.3.4 EUEuropean Union3.3.5 FARFaraday Cup3.3.6 HEUhigh enriched uranium3.3.7 IAEAInternational Atomic Energy Agency3.3.8 ICPMSinductively coupled mass spectrometry3.3.9 IRMMInstit

27、ute for Reference Materials and Measurements (since 1 July 2016 called JRC-Geel, the only unit workingwith nuclear materials at JRC-Geel is JRC-G.2)3.3.10 ITUInstitute for Transuranium Elements (since 1 July 2016 called JRC-Karlsruhe, the only unit involved with thermalionization mass spectrometry m

28、easurements of nuclear materials at JRC-Karlsruhe is JRC-G.II.6)3 The last approved version of this historical standard is referenced on www.astm.org.C1871 18a23.3.11 JRCJoint Research Centre3.3.12 LEUlow enriched uranium3.3.13 MTEmodified total evaporation3.3.14 NBLNew Brunswick Laboratory (since 1

29、5 May 2016 called NBL-Program Office)3.3.15 NMLNuclear Material Laboratory (part of the IAEA)3.3.16 QCquality control3.3.17 RSDrelative standard deviationSD (see below) divided by the mean value of the observations in repeated sampling.3.3.18 RSErelative standard errorSE (see below) divided by the m

30、ean value of the observations in repeated sampling.3.3.19 SDstandard deviationaccording to Practice E2586, 3.1.30: The square root of the sum of the squared deviations ofthe observed values in the sample divided by the sample size minus 1.3.3.20 SEstandard erroraccording to Practice E2586, 3.1.29: S

31、tandard deviation of the population of values of a samplestatistic (that is, the mean value) in repeated measurements, or an estimate of it.3.3.20.1 DiscussionAccording to Practice E2586, 3.1.30: If the standard error (SE, see above) of a statistic is estimated, it will itself be a statistic withsom

32、e variance that depends on the sample size, that is, the number of observed values in the sample (Practice E2586, 3.1.26).3.3.20.2 DiscussionAccording to Practice E2655, 5.8.4.1: From statistical theory, a 95 % confidence interval for the mean of a normal distribution,given n independent observation

33、s x1, x2, ., xn drawn from the distribution, is x 6 t SD / n, where x is the sample mean,SD is the standard deviation of the observations (see above), and t is the 0.975 percentile of the Students t distribution with n-1degrees of freedom. Because Students t distribution approaches the normal as n i

34、ncreases, the value of t approaches 1.96 as nincreases. This is the basis for using the (coverage) factor 2 for expanded uncertainty. The standard error (SE) of the mean valueof a series of n independent repeated measurements can be derived from that by using t = 1, so the standard error (SE) is giv

35、enby SD / n.3.3.21 TIMSthermal ionization mass spectrometry3.3.22 WRMworking reference material4. Summary of Test Method4.1 The double spike method has been developed with the intention to improve the precision and decrease the uncertainties for235U/238U major isotope ratio measurements compared to

36、the known methods such as the “classical” total evaporation technique(1-4),4 also described in Test Method C1672, and the modified total evaporation technique (5 and 6), also described in Test MethodC1832. For the double spike method the mass fractionation correction for the 235U/238U ratio is perfo

37、rmed internally throughoutthe measurement rather than externally, by using the mass fractionation observed for a double spike material with a known orcertified 233U/236U isotope ratio (also spanning three mass units), which is mixed with the sample prior to the measurement, eitherduring the sample p

38、reparation or directly on the TIMS filament. If necessary, uranium is separated from plutonium and otherelements (to eliminate isobaric interferences) by selective extraction, anion exchange (see Practice C1411), or extractionchromatography. The purified uranium fraction as nitrate solution is loade

39、d onto an evaporation filament (made of metals such asrhenium, zone-refined rhenium, or tungsten with high evaporation temperature), and blended with an appropriate amount of doublespike solution, and converted to an oxide by controlled heating of the filament under atmospheric conditions. In case o

40、nly the235U/238U ratio of the sample has to be determined, it is recommended to mix the sample with the double spike during the loadingprocess on the filament. In case the uranium amount concentration of the sample has to be determined, the sample solution hasto be blended gravimetrically with the d

41、ouble spike solution prior to filament loading, for which weighable amounts have to beused.4.2 The sample amount to be loaded for DS analyses is within a range of about 4 to 6 g to achieve ion beam signals of about20 to 30 V for the major isotope 238U for DU, NU, and LEU samples.4.3 The 235U/238U is

42、otope amount ratios are corrected for mass fractionation for each integration step individually. This isaccomplished in an internal manner, the magnitude of the mass fractionation is calculated from the measured mass fractionationof the 233U/236U ratio.The peak tailing contributions are determined a

43、t two mass positions, 0.5 mass units below and 0.5 mass unitsabove the isotope masses of interest.4 The boldface numbers in parentheses refer to a list of references at the end of this standard.C1871 18a34.4 For the correction of isobaric interferences, a separate measurement of the isotopic composi

44、tion of the (unspiked) sampleis required, unless this information is already available. This measurement can be performed using the TE or MTE methods (TestMethods C1672 and C1832, respectively).5. Significance and Use5.1 Uranium material is used as a fuel in certain types of nuclear reactors. To be

45、suitable for use as nuclear fuel, the startingmaterial shall meet certain specifications such as those described in Specifications C753, C776, C787, C833, C967, C996, andC1008, or as specified by the purchaser. The 235U/238U isotope amount ratios and the amount content of uranium material can bemeas

46、ured by mass spectrometry following this test method to ensure that they meet the specification.5.2 The double spike method has been used for studies of uranium fractionation effects in isotope geochemistry andcosmochemistry, for uranium source attribution in nuclear forensics and for investigation

47、of conversion or sampling processes innuclear industry and nuclear safeguards (7-11). Most recently, the double spike method has been used for the validation of theCristallini sampling method of UF6 (12 and 13). The double spike method can be used for a wide range of sample sizes even insamples cont

48、aining as low as 50 g of uranium. The concentration of the loading solution for the DS method has to be in the rangeof 1 to 6 mg/g to allow a sample loading of 4 to 6 g of uranium.Aminimum loading of 4 g uranium per filament is recommended.5.3 The measurement of 236U/238U ratios using this method is

49、 not possible due to the large isobaric interference from the 236Uion beam of the double spike onto the 236U ion beam from the sample (50.000 times for close to natural material, for example,like IRMM-184).5.4 The application of the double spike method for measurements of 235U/238U ratio is limited by the isobaric interferencebetween the 236U from the double spike material and the 236U contained in the sample.As a consequence, the method is not suitablefor samples which contain significant amounts of 236U due to prior neutron capt