ASTM_C_1108_-_12.pdf

Designation:C110812Standard Test Method forPlutonium by Controlled-Potential Coulometry1This standard is issued under the fixed designation C1108;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 describes the determination of dis-solved plutonium from unirradiated nuclear-grade(that is,high-purity)materials by controlled-potential coulometry.Controlled-potential coulometry may be performed in a choiceof supporting electrolytes,such as 0.9 M HNO3,1 M HClO4,1M HCl,5 M HCl,and 0.5 M H2SO4.Limitations on the use ofselected supporting electrolytes are discussed in Section 5.Optimum quantities of plutonium for this procedure are 5 to 20mg.1.2 Plutonium-bearing materials are radioactive and toxic.Adequate laboratory facilities,such as gloved boxes,fumehoods,controlled ventilation,etc.,along with safe techniquesmust be used in handling specimens containing these materials.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 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:2C859 Terminology Relating to Nuclear MaterialsC1009 Guide for Establishing and Maintaining a QualityAssurance Program forAnalytical Laboratories Within theNuclear IndustryC1068 Guide for Qualification of Measurement Methods bya Laboratory Within the Nuclear IndustryC1128 Guide for Preparation of Working Reference Materi-als for Use in Analysis of Nuclear Fuel Cycle MaterialsC1156 Guide for Establishing Calibration for a Measure-ment Method Used to Analyze Nuclear Fuel Cycle Mate-rialsC1168 Practice for Preparation and Dissolution of PlutoniumMaterials for AnalysisC1210 Guide for Establishing a Measurement System Qual-ity Control Program for Analytical Chemistry Laborato-ries Within the Nuclear IndustryC1297 Guide for Qualification of Laboratory Analysts forthe Analysis of Nuclear Fuel Cycle MaterialsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Summary of Test Method3.1 In a controlled-potential coulometric measurement,thesubstance being determined reacts at a stationary electrode,thepotential of which is maintained at such a value that unwantedelectrode reactions are precluded under the prevailing experi-mental conditions.Those substances which have reduction-oxidation(redox)potentials near that of the ion being deter-mined constitute interferences.Electrolysis current decreasesexponentially as the reaction proceeds,until constant back-ground current is obtained.Detailed discussions of the theoryand applications of this technique have been published(1,2,3,4,5,6).3The control-potential adjustment technique(7)can beused to terminate the electrolysis of the specimen at constantbackground current without exhaustive electrolysis with con-siderable reduction in operating time.Use of the control-potential adjustment technique requires that the coulometerintegrator be capable of operations in a bipolar mode and thatthe plutonium-containing solution be of high purity,that is,nuclear grade.3.2 Plutonium(IV)is reduced to Pu(III)at a working elec-trode maintained at a potential more negative than the formalredox potential.Plutonium(III)is oxidized to Pu(IV)at apotential more positive than the formal redox potential.Thequantity of plutonium electrolyzed is calculated from the netnumber of coulombs required for the electrolysis,according toFaradays law.Corrections for incomplete reaction,derivedfrom the Nernst equation,must be applied for electrolysis ofthe sample aliquot(7,8).1This 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 July 1,2012.Published July 2012.Originally approvedin 1988.Last previous edition approved in 2006 as C1108 99(2006).DOI:10.1520/C1108-12.2For 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.3The boldface numbers in parentheses refer to the list of references at the end ofthis test method.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 W 5Qs2 Qb!MnFf(1)where:W=grams of plutonium,Qs=coulombs required by the electrolysis,Qb=coulombs of background current,M=gram-atomic weight of plutonium(must be adjustedfor isotop