1、Designation: C1428 11C1428 18Standard Test Method forIsotopic Analysis of Uranium Hexafluoride bySingleStandard Gas Source Multiple Collector MassSpectrometer Method1This standard is issued under the fixed designation C1428; the number immediately following the designation indicates the year oforigi
2、nal 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 is applicable to the isotopic analysis of urani
3、um hexafluoride (UF6) with 235U concentrations less than orequal to 5 % and 234U, 236U concentrations of 0.0002 to 0.1 %.1.2 This test method may be applicable to the analysis of the entire range of 235U isotopic compositions providing that adequateCertified Reference Materials (CRMs or traceable st
4、andards) are available.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 health safety, health, and environmental practices and determine theapplicability of
5、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 Standards, Guides and Recommendations issuedby the World Trade O
6、rganization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C787 Specification for Uranium Hexafluoride for EnrichmentC859 Terminology Relating to Nuclear MaterialsC996 Specification for Uranium Hexafluoride Enriched to Less Than 5 % 235U2.2 Other Document:USEC
7、-651 Uranium Hexafluoride: A Manual of Good Handling Practices33. Terminology3.1 For definitions of terms relating to the nuclear fuel cycle, refer to Terminology C859.4. Summary of Test Method4.1 The unknown sample and a CRM or traceable standard whose isotopic composition is close to that of the s
8、ample areintroduced in sequence into the mass spectrometer, and 234U, 235U, 236U, and 238U ions are focused through correspondingcollector slits to the four separate collectors. Measurements are made that are proportional to the ratios of 234U, 235U, or 236Uto 238U. With the known composition of the
9、 CRM or traceable standard, these ratios of molar ratios permit calculation of the 234U,235U, and 236U contents. Memory corrections are applied based on the periodic measurement of two CRMs or traceable standards.5. Significance and Use5.1 Uranium hexafluoride is a basic material used to produce nuc
10、lear reactor fuel. To be suitable for this purpose, the materialmust meet criteria for isotopic composition. This test method is designed to determine whether the material meets the requirementsdescribed in Specifications C787 and C996.1 This test method is under the jurisdiction of ASTM Committee C
11、26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.Current edition approved March 1, 2011Nov. 1, 2018. Published April 2011December 2018. Originally approved in 1999. Last previous edition approved in 20052011as C142899(2005).C1428 11. DOI: 10.1520/C1
12、428-11.10.1520/C1428-18.2 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 website.3 Available from United States Enrich
13、ment Corporation, 6903 Rockledge Drive, Bethesda, MD 20817.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 chang
14、es 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 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Uni
15、ted States16. Apparatus6.1 A gas source multiple collector mass spectrometer with the following attributes:6.1.1 The resolving power of the mass spectrometer is not less than 500. The resolving power (R) is calculated from theregistered mass spectrum of both the 235UF5+ and 238UF5+ isotopes as follo
16、ws:R 5 aMbM (1)wherewhere:a = distance between centers of the 235UF5+ and 238UF5+ peaks,b = peak width of the 238UF5+ isotope (10 % valley),M = 333 mass(u) 238UF5+, andM = 3 = 333 330, 330 mass(u) 235UF5+.6.1.2 The abundance sensitivity of the mass spectrometer is specified as less than 1105 as cont
17、ribution of mass 333 (238UF5+)to mass 331 (236UF5+).6.1.3 The four collectors have collector slits adjusted for ions of masses 329, 330, 331, and 333. Ion currents are amplified byfour amplifiers, having noise level less than 0.5 mV.6.1.4 The ion beams are kept within the slits by an automatic beam
18、positioner circuit.6.1.5 The pumping system of the mass spectrometer analyser tube shall maintain a pressure less than 5108 torr with a sampleflowing into the ion source.6.1.6 The memory correction factor of the mass spectrometer as defined in 9.110.1 shall be consistent with the required accuracyan
19、d precision, and shall not exceed 1.005.6.1.7 The sample inlet system shall be equipped with a manifold, including adjustable leak, and valves for introducing thesample and CRM or traceable standard in sequence and for evacuating corresponding lines. The pumping system of the inletsystem must mainta
20、in a pressure less than 2102 torr by evacuating.7. Hazards7.1 Since UFUranium hexafluoride (UF6) is radioactive, toxic, and highly reactive,reactive especially with reducing substancesand moisture (see USEC-651), appropriate facilities and practices for analysis shall be provided.moisture. Appropria
21、te laboratoryfacilities, materials of construction, and techniques shall be utilized when handling UF6 (see for example USEC-651).7.2 When released to atmosphere, gaseous UF6 reacts with moisture to produce HF gas and toxic UO2F2 particulates. Usesufficient ventilation or respiratory protection to a
22、void breathing fumes. Use appropriate personal protective equipment such asgloves, eye, and face protection. Consult the Safety Data Sheet (SDS) for additional information.8. Calibration and Standardization8.1 Uranium Hexafluoride IsotopicIsotopic:8.1.1 Two CRMs or traceable standards are used to de
23、termine the memory correction factor. The 235U concentration ratio ofupper CRM or traceable standard C235SH ! to 235U of lower CRM or traceable standard C235SL ! shall not be more than three C235SH /C235SL #3).8.1.2 For memory correction factor determination for 234U and 236U isotopes, two CRMs or t
24、raceable standards are used whichdiffer in 234U (236U) concentration. In concentration range 0.0002 to 0.01,C234 236!SH /C234 236!SL #8; in concentration range 0.01 to0.1,C234 236!SH /C234 236!SL #6.8.1.3 The CRMs or traceable standards used for measurements may differ in 235U concentration from a s
25、ample. C235X ! oncondition that C235SH /C235X #1.5 and C235X /C235SL #1.5. For 234U (236U) isotopes, the following range limitations shall be used: 0.0002 to0.01 C234236!SH /C234236!X #4,C234236!X /C234236!SL #4; in concentration range 0.01 to 0.1 C234236!SH /C234236!X #3,C234236!X /C234236!SL #3.9.
26、 ProcedureA typical sequence for the analytical determination is X, S, X, S, where X and S mean the introduction of the sample and theCRM or traceable standard, respectively. Each introduction is followed by ion source evacuation before the next introduction.During each introduction, a simultaneous
27、measurement of the four uranium isotopes occurs.The intensities of the 238UF5+ ion beam for both sample and CRM or traceable standard introduction shall not differ morethan 3 %. Adjustment is performed by pressure equalization of the sample and standard in the inlet system.The number of introduction
28、s per analytical sequence is dependent on the precision required.9.1 Attach sample containers containing the appropriate sample, X, and standard, S, to the inlet system, and prepare bothmaterials for introduction into the ion source as follows:9.1.1 Operate the appropriate valves to remove air entra
29、pped in the connectors and to check that there are no leaks in inletsystem.9.1.2 Freeze the UF6 by immersing the sample container (the unknown sample) into a mixture of water and ice.9.1.3 Open the valve on the container to permit evacuation of volatile impurities, and then close the valve.C1428 182
30、9.1.4 Remove the coolant from around the container and allow the UF6 to return to room temperature.9.1.5 Repeat 8.1.29.1.2 8.1.49.1.4 for the CRM or traceable standard.9.2 Operation of the Mass SpectrometerSpectrometer:9.2.1 Operate appropriate valves to admit the CRM or traceable standard into the
31、ion source.9.2.2 Adjust the accelerating voltage or magnet current to focus the ion beams 234UF5+, 235UF5+, 236UF5+, and 238UF5+ totheir corresponding collectors. Adjust the mass spectrometer parameters to obtain the maximum 238UF5+ ion current andmaximum resolution.9.2.3 Regulate the adjustable lea
32、k to obtain a 238UF5+ ion current of about 109 A.9.2.4 Measure the ion current ratio of 234U, 235U, and 236U to 238U.9.2.5 Terminate the flow of the CRM or traceable standard and evacuate the ion source.9.2.6 Repeat 8.2.19.2.1, 8.2.49.2.4, and 8.2.59.2.5 for the sample.10. Calculation10.1 The memory
33、 correction factor M is calculated by the formula:Mi 5EiS12EiS2EiS2riS12riS2riS2(2)where:Mi = memory correction factor,EiS1,EiS2 = molar ratios of isotope of interest to 238U is calculated from certified data of the two CRMs or traceable standards takenfor memory determination,riS1 = measured ion cu
34、rrent ratio of isotope of interest to 238U for CRM or traceable standard 1, andriS2 = measured ion current ratio of isotope of interest to 238U for CRM or traceable standard 2.10.2 The ratio of molar ratios for the CRMs or traceable standards is calculated as follows:RiS 5riS1riS2 (3)10.3 The ratio
35、of molar ratios for the sample is calculated as follows:RiX 5riXriS (4)where:riX = measured ion current ratio of isotope of interest to 238U for the sample, andriS = measured ion current ratio of isotope of interest to 238U for the working CRM or traceable standard.10.4 The corrected molar ratio EiX
36、 is calculated for the sample using the memory correction factor, Mi, and certified data of theCRM or traceable standard:EiX 511MiRiX 21!#EiS (5)where:EiS = ratio of certified molar concentrations of isotope of interest to 238U for the working CRM or traceable standard.10.5 Calculate the molar conce
37、ntration of isotope of interest for the sample:CiX 5 EiX10011(EjX (6)where:EjX = corrected molar ratios for 234U, 235U, and 236U (see 9.4).EjX = corrected molar ratios for 234U, 235U, and 236U (see 10.4).10.6 Calculate the weight percent for 234U, 235U, and 236U as follows:Ci 5 CiXAi(CjXAj (7)where:
38、CjX = molar concentration of the isotope j,Ai = atomic mass of the isotope i of interest, andC1428 183TABLE 1 Uranium Isotopic CRMs ResultsMass-spectrometer A Mass-spectrometer BCRMsused for determination ofthe memory correction factorReg. No. RM, Lot number,Certified values,Isotope Mass Fraction, %
39、CRM 7533-99, 207-05(Working CRM)CRM 7523-99, 210-06 CRM 7533-99, 207-05(Working CRM)CRM 7520-99, 3-79C235S 54.95120.0024 C235S 51.20470.0005 C235S 54.95120.0024 C235S 50.50400.0003C234S 50.046120.00015 C234S 50.007470.00002 C234S 50.046120.00015 C234S 50.00350.0001C236S 50.015210.00010 C236S 50.0023
40、10.00002 C236S 50.015210.00010 C236S 50.00600.0001CRMsused as a sampleReg. No. RM, Lot number,Certified values,Isotope Mass Fraction, %CRM 7530-99, 186-01 CRM 7530-99, 186-01C235X C234X C236X C235X C234X C236X4.0032 0.0019 0.0360 0.0002 0.0133 0.0002 4.0032 0.0019 0.0360 0.0002 0.0133 0.0002Mean sCi
41、XdsCiXd 4.0024 0.03590 0.01324 4.0035 0.03595 0.01328Quantity of determinationsunder repeatability (n)9 9 9 10 10 10Relative standarduncertainty, %0.006 0.12 0.43 0.006 0.09 0.33Bias sCiX2C iXdsCiX2C iXd 0.0008 0.00010 0.00006 0.0003 0.00005 0.00005CRMsused for determination ofthe memory correction
42、factorReg. No. RM, Lot number,Certified values,Isotope Mass Fraction, %CRM 7533-99, 207-05(Working CRM)CRM 7523-99, 210-06 CRM 7533-99, 207-05 CRM 7520-99, 3-79(Working CRM)C235S 54.95120.0024 C235S 51.20470.0005 C235S 54.95120.0024 C235S 50.50400.0003C234S 50.046120.00015 C234S 50.007470.00002 C234
43、S 50.046120.00015 C234S 50.00350.0001C236S 50.015210.00010 C236S 50.002310.00002 C236S 0.015210.00010 C236S 50.00600.0001CRMsused as a sampleReg. No. RM, Lot number,Certified values,Isotope Mass Fraction, %CRM 7527-99, 219-08 CRM 7527-99, 219-08C235X C234X C236X C235X C234X C236X2.8250 0.0011 0.0254
44、5 0.0001 0.00070 0.00003 2.8250 0.0011 0.02545 0.0001 0.00070 0.00003Mean sCiXdsCiXd 2.8248 0.02542 0.00072 2.8243 0.02544 0.00067Quantity of determinationsunder repeatability (n)10 10 10 10 10 10Relative standarduncertainty, %0.005 0.13 5.2 0.009 0.14 7.2Bias sCiX2C iXdsCiX2C iXd 0.0002 0.00003 0.0
45、0002 0.0007 0.00001 0.00003CRMsused for determination ofthe memory correction factorReg. No. RM, Lot number,Certified values,Isotope Mass Fraction, %CRM 7520-99, 3-79 CRM 7523-99, 210-06(Working CRM)CRM 7520-99, 3-79 CRM 7523-99, 210-06(Working CRM)C235S 50.50400.0003 C235S 51.20470.0005 C235S 50.50
46、400.0003 C235S 51.20470.0005C234S 50.00350.0001 C234S 50.007470.00002 C234S 50.00350.0001 C234S 50.007470.00002C236S 50.00600.0001 C236S 50.002310.00002 C236S 50.00600.0001 C236S 50.002310.00002CRMused as a sampleReg. No. RM, Lot number,Certified values,Isotope Mass Fraction, %CRM 7521-99, 184-00 CR
47、M 7521-99, 184-00C235X C234X C236X C235X C234X C236X0.71049 0.00029 0.00531 0.00007 0.00002 0.71049 0.00029 0.00531 0.00007 0.00002Mean sCiXdsCiXd 0.710496 0.00533 . . . 0.710463 0.005312 . . .Quantity of determinationsunder repeatability (n)10 10 . . . 10 10 . . .Relative standarduncertainty, %0.03
48、 0.7 . . . 0.02 0.8 . . .Bias sCiX2C iXdsCiX2C iXd 0.000006 0.00002 . . . 0.000027 0.000002 . . .C1428184Aj = atomic masses of the isotope j.11. Precision and Bias11.1 Isotopic uranium CRMs have been analyzed in 2009. The measurements were conducted in one laboratory on two massspectrometers by vari
49、ous operators.11.2 PrecisionFor each CRM, the average measured value, CiXCiX, is given together with the relative standard uncertainty,obtained for n experiments under repeatability. Results are listed in Table 1.11.3 BiasIn accordance with Table 1, the method shows no statistically significant bias.12. Keywords12.1 gas source multiple collector mass spectrometer; uranium hexafluoride isotopic CRM or traceable standard; uraniumisotopesASTM Internationa
