1、Designation:C145700(Reapproved 2010)1Standard Test Method forDetermination of Total Hydrogen Content of Uranium OxidePowders and Pellets by Carrier Gas Extraction1This standard is issued under the fixed designation C1457;the number immediately following the designation indicates the year oforiginal
2、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.1NOTEEditorial corrections were made throughout in June 2010.1.Scope1.1 This test meth
3、od applies to the determination of hydro-gen in nuclear-grade uranium oxide powders and pellets todetermine compliance with specifications.Gadolinium oxide(Gd2O3)and gadolinium oxide-uranium oxide powders andpellets may also be analyzed using this test method.1.2 This standard describes a procedure
4、for measuring thetotal hydrogen content of uranium oxides.The total hydrogencontent results from absorbed water,water of crystallization,hydro-carbides and other hydrogenated compounds which mayexist as fuels impurities.1.3 This test method covers the determination of 0.05 to 200g of residual hydrog
5、en.1.4 This test method describes an electrode furnace carriergas combustion system equipped with a thermal conductivitydetector.1.5 The preferred system of units is micrograms hydrogenper gram of sample(g/g sample)or micrograms hydrogen pergram of uranium(g/g U).1.6 The values stated in SI units ar
6、e to be regarded asstandard.No other units of measurement are included in thisstandard.1.7 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
7、 determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C753 Specification for Nuclear-Grade,Sinterable UraniumDioxide PowderC776 Specification for Sintered Uranium Dioxide PelletsC888 Specification for Nuclear-Grade Gadolinium Oxide(Gd2O3)Powde
8、rC922 Specification for Sintered Gadolinium Oxide-UraniumDioxide Pellets3.Summary of Test Method3.1 The total hydrogen content is determined using a hy-drogen analyzer.The hydrogen analyzer is based on the carriergas method using argon or nitrogen as carrier gas.The actualconfiguration of the system
9、 may vary with vendor and model.3.2 The samples to be analyzed are dropped into a preheatedgraphite crucible,and then,heated up to a temperature of morethan 1700C in a graphite crucible.At that temperaturehydrogen,oxygen,nitrogen,and carbon monoxide(oxygen isconverted to CO when it reacts with the c
10、rucible)are released.The release gas is purified in the carrier gas stream byoxidation and absorption columns.The hydrogen is separatedby chromatographic means and analyzed in a thermal conduc-tivity detector.4.Significance and Use4.1 Uranium dioxide is used as a nuclear-reactor fuel.Gadolinium oxid
11、e is used as an additive to uranium dioxide.Inorder to be suitable for this purpose,these materials must meetcertain criteria for impurity content.This test method isdesigned to determine whether the hydrogen content meetsSpecifications C753,C776,C888,and C922.1This test method is under the jurisdic
12、tion ofASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved June 1,2010.Published June 2010.Originallyapproved in 2000.Last previous edition approved in 2005 as C1457 00(2005).DOI:10.1520/C1457-00R10E01.2For refere
13、nced 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohoc
14、ken,PA 19428-2959.United States1 5.Interferences5.1 Contamination of carrier gas,crucibles,or samples withextraneous sources of hydrogen may cause a positive bias.Ablank correction will help to minimize the bias from carrier gasand crucibles.Interference from adsorbed hydrogen onsamples may be elimi
15、nated by keeping the sample in an inertatmosphere or vacuum.5.2 The purification system typically associated with therecommended combustion and detection equipment is de-signed to minimize other expected sources of interferences,such as sulfur,halogens,carbon monoxide,carbon dioxide,andwater.5.2.1 T
16、he nitrogen and hydrogen peaks are close togetherand must be well-separated to prevent falsely high result fromthe nitrogen.The molecular sieve must be sufficiently long toseparate the peaks and must be changed when the columnbecomes loaded with contaminants that prevent proper peakseparation.5.3 The temperature of 17001800C must be reached.Ifnot,the decomposition of the released water to hydrogen andcarbon monoxide may not be complete.The temperature willdepend upon the instrument and type of g