1、Designation:C181716Standard Test Method forThe Determination of the Oxygen to Metal(O/M)Ratio inSintered Mixed Oxide(U,Pu)O2)Pellets by Gravimetry1This standard is issued under the fixed designation C1817;the number immediately following the designation indicates the year oforiginal adoption or,in t
2、he 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 practice is an alternative method to Test MethodC698 for the determination of the oxyg
3、en-to-metal atom ratio(O/M)in sintered mixed oxide fuel(MOX)pellets.The methodpresented in Test Method C698 is a one-step thermogravimet-ric method for determining O/M ratio in sintered MOXpowders and pellets.As stated in Test Method C698,thermo-gravimetric methods using a two-step heating cycle are
4、 alsosatisfactory(1,2).2The method presented in this test method isa two-step heating cycle method.This test method is applicableto sintered MOX pellets containing up to 10 weight percentPuO2.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included i
5、n 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 determine the applica-bility of regulatory limitations prior to use.2.R
6、eferenced Documents2.1 ASTM Standards:3C698 Test Methods for Chemical,Mass Spectrometric,andSpectrochemical Analysis of Nuclear-Grade Mixed Ox-ides(U,Pu)O2)C753 Specification for Nuclear-Grade,Sinterable UraniumDioxide PowderC757 Specification for Nuclear-Grade Plutonium DioxidePowder,SinterableC833
7、 Specification for Sintered(Uranium-Plutonium)Diox-ide PelletsC859 Terminology Relating to Nuclear MaterialsC1068 Guide for Qualification of Measurement Methods bya Laboratory Within the Nuclear IndustryC1672 Test Method for Determination of Uranium or Pluto-nium Isotopic Composition or Concentratio
8、n by the TotalEvaporation Method Using a Thermal Ionization MassSpectrometerD1193 Specification for Reagent WaterD1356 Terminology Relating to Sampling and Analysis ofAtmospheres2.2 ISO Standards:4ISO 21484 Nuclear Fuel Technology Determination of theO/M Ratio in MOX Pellets Gravimetric Method First
9、Edition3.Terminology3.1 For definitions of terms used in this test method but notdefined herein,refer to Terminology C859.3.2 Definitions of Terms Specific to This Standard:3.2.1 average of the relative atomic massthe weightedaverage of the relative atomic mass of an element calculated asa function
10、of its isotopic composition.3.2.2 mole fractionthe ratio of the number of molecules(or moles)of a compound or element to the total number ofmolecules(or moles)present(Terminology D1356).3.2.3 MOXnuclear fuel composed of a mixture of uraniumand plutonium oxides(U,Pu)O2).3.2.4 O/Mratio of the oxygen a
11、toms divided by the metalatoms in the sample.3.2.5 relative atomic massa dimensionless physicalquantity,the ratio of the average mass of atoms of an element(from a single given sample or source)to112of the mass of anatom of carbon-12(known as the unified atomic mass unit).3.2.6 scavengingthe process
12、 of pushing a gas out byintroducing a fresh flow in.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 Jan.15,2016.Published February 2016.Originallyapproved in 2015.
13、Last previous edition approved in 2015 as C1817 15.DOI:10.1520/C1817-16.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book
14、of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.4Available from International Organization for Standardization(ISO),1,ch.dela Voie-Creuse,CP 56,CH-1211 Geneva 20,Switzerland,http:/www.iso.org.Copyright ASTM International,100 Barr Harbor Drive,PO Bo
15、x C700,West Conshohocken,PA 19428-2959.United States1 3.2.7 sinteringto increase the bonding in a mass of pow-der or a compact by heating below the melting point of themain constituent.4.Summary of Test Method4.1 The purpose of the analysis is to test the stoichiometryof the MOX pellet by the determ
16、ination of the O/M ratio.Theprinciple of the method is that one or a number of MOX pelletsare heated under a specific set of atmospheric conditions inorder to add or subtract oxygen molecules to the MOX pellets.This process results in an O/M ratio of 2 in the MOX pelletsafter heating.The mass of the oxygen molecules added to orsubtracted from the MOX pellets to achieve an O/M ratio of 2is quantified by weighing the MOX pellets before and after theheating step.Once the difference in mass is known