ASTM_C_1477_-_08_2014.pdf

Designation:C147708(Reapproved 2014)Standard Test Method forIsotopic Abundance Analysis of Uranium Hexafluoride andUranyl Nitrate Solutions by Multi-Collector,InductivelyCoupled Plasma-Mass Spectrometry1This standard is issued under the fixed designation C1477;the number immediately following the designation indicates the 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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the isotopic abundance analysisof234U,235U,236U and238U in samples of hydrolysed ura-nium hexafluoride(UF6)by inductively coupled plasmasource,multicollector,mass spectrometry(ICP-MC-MS).Themethod applies to material with235U abundance in the range of0.2 to 6%mass.This test method is also described in ASTMSTP 1344.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard does 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 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 Analysis ofUranium HexafluorideC787 Specification for Uranium Hexafluoride for Enrich-mentC996 Specification for Uranium Hexafluoride Enriched toLess Than 5%235UD1193 Specification for Reagent Water2.2 Other Document:STP 1344 Applications of Inductively Coupled Plasma-Mass Spectrometry(ICP-MS)to Radionuclide Determi-nations33.Terminology3.1 Acronyms:3.1.1 amuatomic mass unit3.1.2 ICP-MC-MSInductively Coupled Plasma Multi-Collector Mass Spectrometer3.1.3 ICP-MSInductively Coupled Plasma Mass Spec-trometer3.1.4 UIRMUranium Isotopic Reference Material4.Summary of Test Method4.1 Samples are received either in the form of uraniumhexafluoride(UF6)or aqueous uranic solution.The UF6samples are hydrolysed,diluted and acidified with nitric acid.Uranic solution samples are diluted and acidified with nitricacid.If required,an internal reference of thorium isotopes canbe subsequently added to each diluted sample.As detailed inSection 8,isotope pairs of elements other than thorium couldbe used for an internal reference.4.2 The samples are contained in polypropylene tubes thatare inserted into the auto-sampler rack of the mass spectrom-eter.Sample details are input to the computer and the instru-ment is prepared for measurement.The automatic measuringsequence is initiated.4.3 Uranium Isotopic Reference Materials(UIRMs)areused to calibrate the instrument.Each UIRM is prepared inaqueous solution(acidified with nitric acid)and if requiredspiked with the same internal reference as the samples.Thiscalibration solution is measured and a mass bias parameter is1This test method is under the jurisdiction ofASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved Jan.1,2014.Published February 2014.Originallyapproved in 2000.Last previous edition approved in 2008 as C1477 08.DOI:10.1520/C1477-08R14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from ASTM Headquarters.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 calculated that is stored and subsequently imported into each ofthe sample measurements4to correct the measured uraniumisotopic ratios.4.4 Measurements of isotopic ratios in the calibration solu-tion and the subsequent samples are initiated by customisedsoftware.The mass bias factor is computed from the measuredisotopic ratios in the calibration solution.This parameter isthen exported to correct the measured isotopic ratios of thesamples for mass bias.The corrected isotopic abundances areexpressed as%atomic and are converted to%mass prior toreporting.Details of the mass bias correction are presented inAppendix X1.5.Significance and Use5.1 The test method is capable of measuring uraniumisotopic abundances of234U,235U,236U and238U as requiredby Specifications C787 and C996.6.Interferences6.1 Mass BiasElectrostatic repulsion between uraniumions causes a so-called“mass bias”effect.Mass bias isobserved as an enhancement in the number of ions detected atthe collectors from the heavier uranium isotopes relative to thelighter uranium isotopes.A calibration procedure is used tocorrect the mass spectrometer for mass bias.6.2 Adjacent Isotopic PeaksThe abundance sensitivity ofthe ICP-MC-MS at mass 237 is specified to be less than 0.5parts per million of the238U ion beam.The method i