ASTM_C_1636_-_13.pdf

Designation:C163613Standard Guide for theDetermination of Uranium-232 in Uranium Hexafluoride1This standard is issued under the fixed designation C1636;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 method covers the determination of232U in ura-nium hexafluoride by alpha spectrometry.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 to determine theapplicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C787 Specification for Uranium Hexafluoride for Enrich-mentC996 Specification for Uranium Hexafluoride Enriched toLess Than 5%235UC1163 Practice for Mounting Actinides for Alpha Spectrom-etry Using Neodymium FluorideC1284 Practice for Electrodeposition of the Actinides forAlpha SpectrometryC1474 Test Method for Analysis of Isotopic Composition ofUranium in Nuclear-Grade Fuel Material by QuadrupoleInductively Coupled Plasma-Mass SpectrometryD1193 Specification for Reagent WaterD3084 Practice for Alpha-Particle Spectrometry of WaterD3648 Practices for the Measurement of Radioactivity2.2 Other StandardsDIN 25711 Determination of the232U isotopic content inuranium containing nuclear fuel solutions by spectrom-etry.3ISO218473 NuclearFuelTechnologyAlphaSpectrometryPart 3:Determination of uranium-232 inuranium and its compounds.3.Terminology3.1 Definitions:3.1.1 region-of-interest(ROI)the channels,or region,inthe alpha spectra in which the counts due to a specificradioisotope appear on a functioning calibrated alpha spec-trometry system.3.1.2 Reagent blankDI water processed the same as thesamples;used in the determination of the minimum detectableactivity.4.Summary of Guide4.1 An aliquot of hydrolyzed uranium hexafluoride equiva-lent to 60 micrograms of uranium is converted to a nitric acidsystem and the uranium is extracted onto a solid phaseextraction column.The daughters of uranium decay productsare rinsed from the column and the uranium is then selectivelyeluted.The uranium is reduced and then coprecipitated withneodymium fluoride.Test Method C1163 provides furtherinformation on the use of neodymium fluoride to prepareactinide mounts for alpha spectrometry.The sample is thencounted by alpha spectrometry,and the232U is calculatedbased on the observed activities of the uranium isotopes in thealpha spectra.4.2 While this guide does not present details on electrode-position as an alternative to neodymium fluoride precipitationfor the preparation of a mount for alpha spectrometry PracticeC1284 does present details on that option.4.3 Alternate separation chemistry approaches may befound in the literature.It is the responsibility of the user of suchalternativeseparationapproachestovalidatethereeffectiveness,especially the removal of potentially interferingthorium isotopes(section 6.1).5.Significance and Use5.1 The method is applicable to the analysis of materials todemonstrate compliance with the specifications set forth inSpecifications C787 and C996.Some other specifications maybe expressed in terms of mass of232U per mass of only238U(see ISO 218473:2007).1This guide is under the jurisdiction of ASTM Committee C26 on Nuclear FuelCycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.Current edition approved Jan.1,2013.Published January 2013.Originallyapproved in 2006.Last previous edition approved in 2006 as C1636 06a.DOI:10.1520/C1636-13.2For 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.3Deutsches Institut fr Normung e.V.,Berlin,Germany(www.din.de).Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Interferences6.1 Incomplete removal of228Th could possibly interferewith the232U determination.Method DIN 25711 addresses thepotential capability for this method to eliminate this potentialinterference.6.2 Since only the relative amount of232U,relative to totaluranium,is being determined in this method there is no impactto chemical loss in the separation or sample mounting chem-istry.Therefore,unlike most alpha spectrometry methods,noyield tracer is necessary or useful.6.3 The alpha emission energies of235U and236U arerelatively close.Thus there is the potential for overlap ofcounts from one isotope into the ROI of the other.Where thealpha spectrometry system(section 7.1)provide