ASTM_D_8091_-_21.pdf

Designation:D809121Standard Guide forImpregnation of Graphite with Molten Salt1This standard is issued under the fixed designation D8091;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 covers procedures for the impregnation ofgraphite with molten salt under a consistent pressure andtemperature.Such procedures are necessary if the user wishesto prepare graphite specimens for testing that represent mate-rial that has been exposed to a molten salt environment in amolten salt nuclear reactor.The user will need to ensure thatimpregnation temperature and pressure conditions reflect thosepertaining to the molten salt environment,noting that theproperties of the material will change once it becomes irradi-ated.NOTE1The term impregnation is used throughout this guide as this isthe correct term for the described process.Other terms such as infiltrationand intrusion may be encountered by the user in other texts and the termintrusion is commonly used to describe penetration of open porosity ingraphite in a molten salt reactor environment.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisguide.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:2B923 Test Method for Metal Powder Skeletal Density byHelium or Nitrogen PycnometryC559 Test Method for Bulk Density by Physical Measure-ments of Manufactured Carbon and Graphite ArticlesD7775 Guide for Measurements on Small Graphite Speci-mens3.Terminology3.1 Definitions:3.1.1 impregnation pressure(PI),nthe differential pres-sure between the cover gas pressure and the pore pressure ofthe graphite specimen.3.1.1.1 DiscussionIf the impregnation starts at a porepressure of atmospheric pressure,the impregnation pressure isthe gauge pressure of the cover gas;if the impregnation startsat a pore pressure of“0”(vacuum),the impregnation pressureis the gauge pressure plus atmospheric pressure.For a porepressure between 0 and atmospheric pressure,the impregnationpressure is(gauge pressure+atmospheric pressure porepressure).3.1.2 impregnation temperature(TI),nthe system tem-perature before the graphite specimen has been immersed inthe molten salt.3.2 Definitions of Terms Specific to This Standard:3.2.1 Parameter Do,na measure of the extent of penetra-tion of the graphite porosity by the molten salt expressed interms of the open pore volume of the specimen.3.2.1.1 DiscussionIf there was no damage to the micro-structure of the graphite during impregnation,then parameterDobased upon open pore volume would be unity at saturation.This parameter is applicable when damage to the graphitemicrostructure during impregnation is absent or low.Mercuryporosimetry studies indicate that the threshold pressure formicrostructural damage is 13.8 MPa to 20.0 MPa(2000 psi to3000 psi).3,4This threshold should be used as a guide by userswhen evaluating Do.At high impregnation pressures,closedporosity may be broken into by the molten salt and parameter1This 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 July 1,2021.Published July 2021.Originally approvedin 2016.Last previous edition approved in 2016 as D8091 16.DOI:10.1520/D8091-21.2For 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.3Dickinson,J.M.,Shore,J.W.,“Observations Concerning the Determination ofPorosities in Graphites,”Carbon,Vol 6,1968,pp.937941.4Baker,D.J.,Morris,J.B.,“Structural Damage in Graphite Occurring duringPore Size Measurements by High Pressure Mercury,”Carbon,Vol 9,1971,pp.687690.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization e