1、Designation:C142999(Reapproved 2014)Standard Test Method forIsotopic Analysis of Uranium Hexafluoride by Double-Standard Multi-Collector Gas Mass Spectrometer1This standard is issued under the fixed designation C1429;the number immediately following the designation indicates the year oforiginal adop
2、tion 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 covers a quantitative test methodapplicable to determining the
3、 mass percent of uranium isotopesin uranium hexafluoride(UF6)samples.This method as de-scribed is for concentrations of235U between 0.1 and 10mass%,and234U and236U between 0.0001 and 0.1 mass%.1.2 This test method is for laboratory analysis by a gas massspectrometer with a multi-collector.1.3 This s
4、tandard complements Test Methods C761,thedouble-standard method for gas mass spectrometers using asingle collector,by providing a method for spectrometers usinga multi-collector.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibi
5、lity 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 Standards:2C761 Test Methods for Chemical,Mass Spectrometric,Spectrochemical,Nuclear,and Radiochemical Analys
6、is ofUranium HexafluorideC787 Specification for Uranium Hexafluoride for Enrich-mentC996 Specification for Uranium Hexafluoride Enriched toLess Than 5%235UC1215 Guide for Preparing and Interpreting Precision andBias Statements in Test Method Standards Used in theNuclear Industry3.Terminology3.1 Defi
7、nitions of Terms Specific to This Standard:3.1.1 A standard,nthe low-value standard of a standardpair that brackets the sample.3.1.2 B standard,nthe high-value standard of a standardpair that brackets the sample.3.1.3 determination,na single isotopic value,calculatedfrom a sequence of ratios;the mos
8、t basic isotopic valuecalculated.3.1.4 Lagranges interpolation formula,na mathematicalequation designed to estimate values between two or moreknown values.3.1.5 run,na completed,six-entry symmetrical sequenceconsisting of A standard,sample,B standard,B standard,sample,and A standard from which a det
9、ermination can becalculated for one or more isotopes.3.1.6 standard spread,nthe difference between the highand low standards;sometimes called standard range.3.1.7 test result,na reported value;the mean of two ormore determinations.4.Summary of Test Method4.1 Uranium hexafluoride gas is introduced in
10、to an ioniza-tion source.The resulting ions are accelerated down the flighttube into the magnetic field.The magnetic field separates theions into ion beams in accordance with the m/e ratio.Fourcollectors are stationed so the234UF5+,235UF5+,236UF5+,and238UF5+ion beams strike individual collectors.4.2
11、 Two standards are chosen whose values bracket thedesired isotope of the sample.The sample and two standardsare introduced in a six-entry,symmetrical sequence.Then,measurements are taken that give the mole ratio of the desiredisotope to238U.4.3 Through Lagranges interpolation formula,these mea-surem
12、ents are used to calculate the mass percent of the desiredisotope.If standards are available that bracket all isotopes,thenthe234U,235U,and236U mass percents are calculated from thesame six-entry run.1This test method is under the jurisdiction of ASTM CommitteeC26 on NuclearFuel Cycle and is the dir
13、ect responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved June 1,2014.Published June 2014.Originallyapproved in 1999.Last previous edition approved in 2009 as C1429 99(2009)1.DOI:10.1520/C1429-99R14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orconta
14、ct ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.4 The results of two six-ent
15、ry,symmetrical-sequence runsare averaged to find test results for each isotope.The238U masspercent is obtained by subtraction.5.Significance and Use5.1 Uranium hexafluoride used to produce nuclear-reactorfuel must meet certain criteria for its isotopic composition.This test method may be used to hel
16、p determine if samplematerials meet the criteria described in Specifications C787and C996.6.Apparatus6.1 Mass spectrometer with the following features andcapabilities:6.1.1 An ion source with an accelerating voltage of approxi-mately 8 kV,6.1.2 A resolving power of greater than or equal to 500,6.1.3 A minimum of three points of attachment for stan-dards or samples,6.1.4 An ion collection system consisting of four collectorcups stationed to collect234UF5+,235UF5+,236UF5+,and238UF5+ions,6.1.5 An i
