1、Designation: C 1428 99 (Reapproved 2005)Standard Test Method forIsotopic Analysis of Uranium Hexafluoride bySingleStandard Gas Source Multiple Collector MassSpectrometer Method1This standard is issued under the fixed designation C 1428; the number immediately following the designation indicates the
2、year oforiginal adoption or, in the case of revision, the year of 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 is applicable to the isotopic anal
3、ysis ofuranium hexafluoride (UF6) with235U concentrations less thanor equal to 5 % and234U,236U concentrations of 0.001 to0.1 %.1.2 This test method may be applicable to the analysis of theentire range of235U isotopic compositions providing thatadequate standards are available.1.3 This standard does
4、 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 health practices and determine the applicability ofregulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2
5、C 787 Specification for Uranium Hexafluoride for Enrich-mentC 996 Specification for Uranium Hexafluoride Enriched toLess than 5 %235U2.2 Other Document:USEC-651 Uranium Hexafluoride: A Manual of Good Han-dling Practices33. Summary of Test Method3.1 The unknown sample and a standard whose isotopiccom
6、position is close to that of the sample are introduced insequence into the mass spectrometer, and234U,235U,236U,and238U ions are focused through corresponding collector slitsto the four separate collectors. Measurements are made that areproportional to the ratios of234U,235U, or236Uto238U. Withthe k
7、nown composition of the standard, these ratios of molarratios permit calculation of the234U,235U, and236U contents.Memory corrections are applied based on the periodic mea-surement of two standards.4. Significance and Use4.1 Uranium hexafluoride is a basic material used to pro-duce nuclear reactor f
8、uel. To be suitable for this purpose, thematerial must meet criteria for isotopic composition. This testmethod is designed to determine whether the material meetsthe requirements described in Specifications C 787 and C 996.5. Apparatus5.1 A gas source multiple collector mass spectrometer withthe fol
9、lowing attributes:5.1.1 The resolving power of the mass spectrometer is notless than 500. The resolving power (R) is calculated from theregistered mass spectrum of both the235UF5+and238UF5+isotopes as follows:R 5a Mb DM(1)wherea = distance between centers of the235UF5+and238UF5+peaks,b = peak width
10、of the238UF5+isotope (10 % valley),M = 333 mass(u)238UF5+, andDM = 3 = 333 330, 330 mass(u)235UF5+5.1.2 The abundance sensitivity of the mass spectrometer isspecified as less than 13105as contribution of mass 333(238UF5+) to mass 331 (236UF5+).5.1.3 The four collectors have collector slits adjusted
11、forions of masses 329, 330, 331, and 333. Ion currents areamplified by four amplifiers, having noise level less than 0.5mV.5.1.4 The ion beams are kept within the slits by an auto-matic beam positioner circuit.1This test method is under the jurisdiction ofASTM Committee C26 on NuclearFuel Cycle and
12、is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved June 1, 2005. Published December 2005. Originallyapproved in 1999. Last previous edition approved in 1999 as C 142899.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cu
13、stomer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Superintendent of Documents, U.S. Government PrintingOffice, Washington, D.C. 20402.1Copyright ASTM International, 100 Barr Harbor D
14、rive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.1.5 The pumping system of the mass spectrometer analy-ser tube shall maintain a pressure less than 53108torr with asample flowing into the ion source.5.1.6 The memory correction factor of the mass spectrom-eter as defined in 9.1 sh
15、all be consistent with the requiredaccuracy and precision, and shall not exceed 1.01.5.1.7 The sample inlet system shall be equipped with amanifold, including adjustable leak, and valves for introducingthe sample and standard in sequence and for evacuatingcorresponding lines. The pumping system of t
16、he inlet systemmust maintain a pressure less than 23102torr by evacuating.6. Hazards6.1 Since UF6is radioactive, toxic, and highly reactive,especially with reducing substances and moisture (see USEC-651), appropriate facilities and practices for analysis shall beprovided.7. Calibration and Standardi
17、zation7.1 Uranium Hexafluoride Isotopic7.1.1 Two standards are used to determine the memorycorrection factor. The relative235U concentration difference ofthese standards shall not be more than 20 %.7.1.2 For memory correction factor determination for234Uand236U isotopes in concentration range 0.01 t
18、o 0.1 %, twostandards are used which differ in234U(236U) concentration.The relative difference shall not exceed two times; in concen-tration range 0.001 to 0.01 %, the relative difference shall notexceed four times.7.1.3 The standards used for measurements may differin235U concentration from a sampl
19、e, but the relative differenceshall not be more than 10 %. The relative difference in234U(236U) concentration shall not exceed two times for theconcentration range 0.001 to 0.01 %, and shall not be morethan 50 % for the concentration range 0.01 to 0.1 %.8. ProcedureA typical sequence for the analyti
20、cal determination is X, S,X, S, where X and S mean the introduction of the sample andthe standard, respectively. Each introduction is followed by ionsource evacuation before the next introduction. During eachintroduction a simultaneous measurement of the four uraniumisotopes occurs.The intensities o
21、f the238U5+ion beam for both sample andstandard introduction shall not differ more than 3 %. Adjust-ment is performed by pressure equalization of the sample andstandard in the inlet system.The number of introductions per analytical sequence isdependent on the precision required.8.1 Attach sample con
22、tainers containing the appropriatesample, X, and standard, S, to the inlet system, and prepareboth materials for introduction into the ion source as follows:8.1.1 Operate the appropriate valves to remove air en-trapped in the connectors and to check that there are no leaksin inlet system.8.1.2 Freez
23、e the UF6by immersing the sample container(the unknown sample) into a mixture of water and ice.8.1.3 Open the valve on the container to permit evacuationof volatile impurities, and then close the valve.8.1.4 Remove the coolant from around the container andallow the UF6to return to room temperature.8
24、.1.5 Repeat 8.1.2-8.1.4 for the standard.8.2 Operation of the Mass Spectrometer8.2.1 Operate appropriate valves to admit the standard intothe ion source.8.2.2 Adjust the accelerating voltage or magnet current tofocus the ion beams234UF5+,235UF5+,236UF5+, and238UF5+totheir corresponding collectors. A
25、djust the mass spectrometerparameters to obtain the maximum238UF5+ion current andmaximum resolution.8.2.3 Regulate the adjustable leak to obtain a238UF5+ioncurrent of about 109A.8.2.4 Measure the ion current ratio of234U,235U, and236Uto238U.8.2.5 Terminate the flow of the standard and evacuate theio
26、n source.8.2.6 Repeat 8.2.1, 8.2.4, and 8.2.5 for the sample.9. Calculation9.1 The memory correction factor M is calculated by theformula:Mi5EiS12 EiS2EiS2riS12 riS2riS2(2)TABLE 1 Uranium Isotopic Standards Results235U (atom %)SRM Certified Values 6absolute errorMeasured ValuesXSrn95.148 90 0.71978
27、6 0.00005 0.71983 0.00028 2595.162 90 2.4377 6 0.0012 2.4373 0.0005 2095.167 90 3.1434 6 0.0015 3.1428 0.0003 2095.173 90 4.252 6 0.002 4.2511 0.0004 20234U (atom %)95.148 90 0.00533 6 0.00005 0.00532 0.000014 2095.173 90 0.0326 6 0.0002 0.0327 0.00007 20236U (atom %)95.173 90 0.0036 6 0.0001 0.0036
28、 0.00018 2095.170 90 0.0199 6 0.0003 0.0202 0.00020 20C 1428 99 (2005)2where:Mi= memory correction factor,EiS1, EiS2= molar ratios of isotope of interest to238Uiscalculated from certified data of the twostandards taken for memory determination,riS1= measured ion current ratio of isotope ofinterest t
29、o238U for Standard 1, andriS2= measured ion current ratio of isotope ofinterest to238U for Standard 2.9.2 The ratio of molar ratios for the standards is calculatedas follows:RiS5riS1riS2(3)9.3 The ratio of molar ratios for the sample is calculated asfollows:RiX5riXriS(4)where:riX= measured ion curre
30、nt ratio of isotope of interestto238U for the sample, andriS= measured ion current ratio of isotope of interestto238U for the working standard.9.4 The corrected molar ratio EiXis calculated for the sampleusing the memory correction factor, Mi, and certified data ofthe standard:EiX5 1 1 Mi RiX2 1!# E
31、iS(5)where:EiS= ratio of certified molar concentrations of isotope ofinterest to238U for the working standard.9.5 Calculate the molar concentration of isotope of interestfor the sample:CiX5EiX 1001 1(EjX(6)where:EjX= corrected molar ratios for234U,235U, and236U (see9.4).9.6 Calculate the weight perc
32、ent for234U,235U, and236Uasfollows:Ci5CiX Ai(CjX Aj(7)where:CjX= molar concentration of the isotope j,Ai= atomic mass of the isotope i of interest, andAj= atomic masses of the isotope j.10. Precision and Bias10.1 Isotopic uranium standards have been analysed from1995 to 1996. The measurements were c
33、onducted in onelaboratory on two mass spectrometers by various operators.10.2 PrecisionFor each standard, the average measuredvalue, X, is given together with the standard deviation, Sr,obtained for n experiments. Results are listed in Table 1.The standards used for measurements differed in isotopic
34、composition from the analyzed standards. The relative differ-ence in235U concentration was equal close to 10 %, and onein234U and236U concentrations was equal close to 50 %.10.3 BiasIn accordance with Table 1, the method showsno statistically significant bias.11. Keywords11.1 gas source multiple col
35、lector mass spectrometer; ura-nium hexafluoride isotopic standards; uranium isotopesASTM 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 advised that determination of the
36、 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 reapproved or withdrawn. Your
37、 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
38、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. Individual 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).C 1428 99 (2005)3
