ASTM_D_8093_-_19.pdf

Designation:D809319An American National StandardStandard Guide forNondestructive Evaluation of Nuclear Grade Graphite1This standard is issued under the fixed designation D8093;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.Scope*1.1 This guide provides general tutorial information regard-ing the application of conventional nondestructive evaluationtechnologies(NDE)to nuclear grade graphite.An introductionwill be provided to the characteristics of graphite that definesthe inspection technologies that can be applied and the limita-tions imposed by the microstructure.This guide does notprovide specific techniques or acceptance criteria for end-userexaminations but is intended to provide information that willassist in identifying and developing suitable approaches.1.2 The values stated in SI units are to be regarded as thestandard.1.2.1 ExceptionAlternative units provided in parenthesesare for information only.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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D7219 Specification for Isotropic and Near-isotropicNuclear GraphitesE94 Guide for Radiographic Examination Using IndustrialRadiographic FilmE1025 Practice for Design,Manufacture,and MaterialGrouping Classification of Hole-Type Image Quality In-dicators(IQI)Used for RadiographyE1441 Guide for Computed Tomography(CT)3.Summary of Guide3.1 This guide describes the impact specific material prop-erties have on the application of three nondestructive evalua-tion technologies:Eddy current/electromagentic testing(ET)(surface/near surface interrogation),ultrasonic testing(UT)(volumetric interrogation),radiographic(X-ray)testing(RT)(volumetric interrogation),to nuclear grade graphite.4.Significance and Use4.1 Nuclear grade graphite is a composite material madefrom petroleum or a coal-tar-based coke and a pitch binder.Manufacturing graphite is an iterative process of baking andpitch impregnation of a formed billet prior to finalgraphitization,which occurs at temperatures greater than2500 C.The impregnation and rebake step is repeated severaltimes until the desired product density is obtained.Integral tothis process is the use of isotropic cokes and a forming process(that is,isostatically molded,vibrationally molded,or ex-truded)that is intended to obtain an isotropic or near isotropicmaterial.However,the source,size,and blend of the startingmaterials as well as the forming process of the green billet willimpart unique material properties as well as variations withinthe final product.There will be density variations from thebillet surface inward and different physical properties with andtransverse to the grain direction.Material variations are ex-pected within individual billets as well as billet-to-billet andlot-to-lot.Other manufacturing defects of interest include largepores,inclusions,and cracks.In addition to the materialvariation inherent to the manufacturing process,graphite willexperience changes in volume,mechanical strength,and ther-mal properties while in service in a nuclear reactor along withthe possibility of cracking due to stress and oxidation resultingfrom constituents in the gas coolant or oxygen ingress.Therefore,there is the recognized need to be able to nonde-structively characterize a variety of material attributes such asuniformity,isotropy,and porosity distributions as a means toassure consistent stock material.This need also includes theability to detect isolated defects such as cracks,large pores andinclusions,or distributed material damage such as material lossdue to oxidation.The use of this guide is to acquire a basicunderstanding of the unique attributes of nuclear grade graphite1This guide is under the jurisdiction of ASTM Committee D02 on PetroleumProducts,Liquid Fuels,and Lubricants and is the direct responsibility of Subcom-mittee D02.F0 on Manufactured Carbon and Graphite Products.Current edition approved Nov.1,2019.Published December 2019.Originallyapproved in 2016.Last previous edition approved in 2016 as D8093 16.DOI:10.1520/D8093-19.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume in