ASTM_C_791_-_12.pdf

Designation:C79112Standard Test Methods forChemical,Mass Spectrometric,and SpectrochemicalAnalysis of Nuclear-Grade Boron Carbide1This standard is issued under the fixed designation C791;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 These test methods cover procedures for the chemical,mass spectrometric,and spectrochemical analysis of nuclear-grade boron carbide powder and pellets to determine compli-ance with specifications.1.2 The analytical procedures appear in the following order:SectionsTotal Carbon by Combustion in an Inductive Furnace andInfrared Measurement7 16Total Boron by Titrimetry and ICP OES17 27Isotopic Composition by Mass Spectrometry28 32Pyrohydrolysis33 40Chloride by Constant-Current Coulometry41 49Chloride and Fluoride by Ion-Selective Electrode50 58Water by Constant-Voltage Coulometry and Weight Loss onDrying59 62Metallic Impurities63 and 64Soluble Boron by Titrimetry and ICP OES65 79Free Carbon by a Coulometric Method80 892.Referenced Documents2.1 ASTM Standards:2C750 Specification for Nuclear-Grade Boron Carbide Pow-derC751 Specification for Nuclear-Grade Boron Carbide PelletsD1193 Specification for Reagent Water3.Significance and Use3.1 Boron carbide is used as a control material in nuclearreactors.In order to be suitable for this purpose,the materialmust meet certain criteria for assay,isotopic composition,andimpurity content.These methods are designed to show whetheror not a given material meets the specifications for these itemsas described in Specifications C750 and C751.3.1.1 An assay is performed to determine whether thematerial has the specified boron content.3.1.2 Determination of the isotopic content of the boron ismade to establish whether the content is in compliance with thepurchasers specifications.3.1.3 Impurity content is determined to ensure that themaximum concentration limit of certain impurity elements isnot exceeded.4.Reagents4.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused,provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.4.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water conformingto Specification D1193.5.Safety Precautions5.1 Many laboratories have established safety regulationsgoverning the use of hazardous chemicals and equipment.Theusers of these methods should be familiar with such safetypractices.6.Sampling6.1 Criteria for sampling this material are given in Specifi-cations C750 and C751.TOTAL CARBON BY COMBUSTION IN ANINDUCTIVE FURNACE AND INFRAREDMEASUREMENT7.Scope7.1 This method covers the determination of total carbon innuclear-grade boron carbide in either powder or pellet form.1These test methods are under the jurisdiction of ASTM Committee C26 onNuclear Fuel Cycle and are the direct responsibility of Subcommittee C26.03 onNeutron Absorber Materials Specifications.Current edition approved June 1,2012.Published July 2012.Originally approvedin 1975.Last previous edition approved in 2011 as C791 11.DOI:10.1520/C0791-12.2For 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.3Reagent Chemicals,American Chemical Society Specifications,AmericanChemical Society,Washington,DC.For suggestions on the testing of reagents notlisted by the American Chemical Society,see Analar Standards for LaboratoryChemicals,BDH Ltd.,Poole,Dorset,U.K.and the United States Pharmacopeia andNational Formulary,U.S.Pharmacopeial Convention,Inc.(USPC),Rockville,MD.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 8.Summary of Test Method8.1 The sample and added combustion accelerators(mostly tungsten-and iron-granules)are heated in an inductivefurnace under oxygen atmosphere.The high-frequency field ofthe furnace couples with electrically conductive components ofsample and combustion accelerators.The sample is heated totemperatures not lower than 1400C and the total carboncontent of the sample is released as carbon dioxide and,partially,as carbon monoxide.The reaction gas is passedthrough a gas-treatment train to ensure that any carbonmonoxide formed is converted to carbon dioxide and to removedust and moisture.The reaction gas is then transferred to theinfrared absorption cell of the analyzer.T