1、Designation: C1853 17Standard Test Method forThe Determination of Carbon (Total) Content in Mixed Oxide(U, Pu)O2) Sintered Pellets by Direct Combustion-InfraredDetection Method1This standard is issued under the fixed designation C1853; the number immediately following the designation indicates the y
2、ear 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 This test method is an alternative to Test Method C69
3、8for the determination of carbon in nuclear grade sintered mixedoxide (MOX) fuel pellets. The method for the determination ofcarbon presented in Test Method C698 consists of combustingcarbon contained in MOX pellets with oxygen in a high-frequency induction furnace and detecting the resulting carbon
4、dioxide using a thermal conductivity cell. The method for thedetermination of carbon presented in this test method consistsof combusting carbon contained in MOX pellets with oxygenin a high-frequency induction furnace and subsequent detectionof the resulting carbon dioxide (CO2) using a non-dispersi
5、veinfrared detector (NDIR). Sulfur oxide is stripped from thecarrier gas stream by a cellulose filter prior to the detection ofCO2.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard may involve hazardous mater
6、ial,operations, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user of this standard toconsult and establish appropriate safety and health practicesand determine the applicability of regulatory limit
7、ations priorto 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 T
8、echnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C698 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 N
9、uclear-Grade Plutonium DioxidePowder for Light Water ReactorsC833 Specification for Sintered (Uranium-Plutonium) Diox-ide Pellets for Light Water ReactorsC859 Terminology Relating to Nuclear MaterialsC1068 Guide for Qualification of Measurement Methods bya Laboratory Within the Nuclear IndustryC1408
10、 Test Method for Carbon (Total) in Uranium OxidePowders and Pellets By Direct Combustion-Infrared De-tection Method2.2 ISO Standards:3ISO 21614 Nuclear Fuel Technology Determination ofCarbon Content of UO2, (U,Gd)O2and (U, Pu)O2Pow-ders and Sintered Pellets Combustion in a High-Frequency Induction F
11、urnace Infrared Absorption Spec-trometry3. Terminology3.1 For definitions of terms used in this test method but notdefined herein, refer to terminology relating to nuclear mate-rials in Terminology C859.3.2 Definitions of Terms Specific to This Standard:3.2.1 MOXnuclear fuel composed of a mixture of
12、 uraniumand plutonium oxides (U, Pu)O2).1This test method is under the jurisdiction of ASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved June 1, 2017. Published June 2017. DOI: 10.1520/C1853-17.2For referenced A
13、STM 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.3Available from International Organization for Standardization (ISO), ISOCentr
14、al Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,Geneva, Switzerland, http:/www.iso.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally r
15、ecognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.2 sinteringthe process of forming a solid mass ofmateria
16、l by heat or pressure, or both, without melting it to thepoint of liquefaction.3.2.3 reference materialnon-matrix matched materialtraceable to a reference material from a national standards bodysuch as the U.S. National Institute for Standards and Technol-ogy (NIST) or equivalent; matrix matched ref
17、erence materialsfor MOX pellets are not available.3.3 Acronyms:3.3.1 NDIRNon Dispersive Infrared Detector.3.3.2 THCTotal Hydrocarbon4. Summary of Test Method4.1 The method consists of crushing a MOX pellet, weigh-ing an approximately 1 g fragment of the pellet into a cruciblewith an accelerator and
18、combustion of the carbon contained inthe sample under a stream of high pressure oxygen in ahigh-frequency induction furnace followed by detection of thecarbon dioxide by a non-dispersive infrared (NDIR) cell.During combustion of the sample, the carbon and sulfurcomponents are oxidized to release car
19、bon monoxide (CO),carbon dioxide (CO2) and sulfur dioxide (SO2). These sampleimpurities are swept by the oxygen (O2) carrier gas through aseries of filters to remove dust and water and then the gasesflow through an oxidation furnace (PtSiO2).All CO is oxidizedto CO2and SO2is oxidized to SO3. The SO3
20、is trapped in acellulose column and the CO2and carrier gas stream flowthrough a selective NDIR detector. Analyzers are oftenequipped with two NDIR cells, one for the detection of carbonand one for sulfur, but this practice describes only the detectionof carbon. The simultaneous detection of carbon a
21、nd sulfur canhowever be performed without impact to the performance ofthis test method, but in this case the cellulose column is notused.4.2 The detector signal plotted against time is a function ofthe concentration of the CO2in the carrier gas. The area belowthe curve (integral) corresponds to the
22、total amount of carbonin the sample. The peak is integrated by the software and theconcentration is calculated taking into account the calibrationfactor, the blank analysis, and the sample weight. The calibra-tion of the analyzer is made by means of a reference material.Blank values are obtained fro
23、m analyzing the pre-ignitedcrucibles with no sample and an accelerator, which is added foroptimum combustion. The blank results are stored. The finalsample result is corrected by the blank value and the results areexpressed in g carbon/g MOX.5. Significance and Use5.1 MOX is used as a nuclear-reacto
24、r fuel. This test methodis designed to determine whether the carbon content of thepellets meet the requirements of the fuel specification. Ex-amples of these requirements are given in Specification C833.5.2 This method is suitable for all sintered MOX pelletscontaining up to 12 weight % PuO2when the
25、 UO2and PuO2meet the requirements of Specifications C753 and C757. Themethod uncertainty is related to the concentration of the carbonin the sample. At lower concentrations, the relative uncertaintyincreases. At carbon contents close to the typical carboncontent specification limit (100 g carbon/gU+
26、Pumetal) themethod uncertainty is on the order of 5 %, but exact methodperformance is difficult to determine due to the lack of matrixmatched certified reference material.6. Interferences6.1 The carbon detectors in the gas analyzer system areselective. The wavelength of detection is chosen to specif
27、icallydetect only carbon dioxide. Furthermore, after the samplecombustion the carrier gas containing the carbon dioxide andother potentially interfering impurities (sulfur, water, and smallparticulate matter) pass through a series of filters and purifyingreagents that remove these impurities from th
28、e carrier gasstream leaving only CO2in the stream at the detector. If theMOX pellets are made from UO2and PuO2that meet therequirements of Specification C753 and C757, all interferencesare eliminated by the purification system.6.2 The crucibles and accelerator chemicals, if they containcarbon, will
29、yield erroneously high results for the sample. Theanalytical method requires the use of pre-ignited crucibles andrunning blanks with accelerator chemical in pre-ignited cru-cible to reduce and correct for the blanks in the results forsamples.6.3 The O2carrier gas could contain water, hydrocarbonsand
30、 CO2and is filtered prior to injection in the samplecombustion chamber to remove these potentially interferingcomponents.6.4 Weighing accuracy of the samples is critical to themethod. If the balance meets the specification in 7.1,iscalibrated in accordance with manufacturers guidance, and ischecked
31、by procedure, the potential for the balance to be asource of error is insignificant.6.5 High levels of halides can damage the NDIR detectorcells. Halides are not typically present in high concentrations insintered MOX fuel pellets and therefore no specific filter isnecessary for removal of halides.7
32、. Apparatus7.1 Analytical Balance, with precision 60.1 mg.7.2 Crucibles, expendable alumina or similar refractorymaterial. The crucible must be pre-ignited at a temperature of900C or higher for a time sufficient to produce constant blankvalues.7.3 Muffle Furnace or Tube Furnace, capable of attaining
33、temperature of 900C, for pre-igniting crucibles.7.4 Desiccator, used to store the pre-ignited crucibles.7.5 Pellet Crusher, used to fragment the pellets.7.6 Carbon Analyzer, consisting of an induction-heatedfurnace suitable for operation at 1600 to 1700C, an NDIR formeasuring carbon dioxide, and aux
34、iliary purification systems.7.6.1 Typical detector range (8 g carbon/gU+Pumetal 1000 g carbon/gU+Pumetal).7.7 Aluminum Foil, used to wrap the ceramic crucibles afterpre-ignition to decrease impurity reabsorption.C1853 1727.8 Tongs and Forceps, for handling crucibles and lids.7.9 Stainless Steel Scoo
35、ps and Spatulas, for handling pelletfragments, accelerator, and reference materials.8. Reagents and Materials8.1 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 A
36、nalytical Reagents of the American Chemical Society,where such specifications are available.4Other 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.8.2 Sodium Hydroxide (NaOH) on a
37、Fibrous SupportCaptures CO2.8.3 Magnesium Perchlorate (Mg(ClO4)2Removes H2O.8.4 Platinized Silica (PtSiO2)Oxidizes any generated COand SO2to CO2and SO3.8.5 Cellulose Trap Packing (Surgical Grade Cotton orEquivalent)Traps SO3.8.6 Quartz WoolFor dust traps and to plug the reagenttubes.8.7 Accelerators
38、Use to achieve complete combustion ofthe samples. Copper metal, tungsten, tin-tungsten mixture,copper oxide, granular tin, and high purity iron chip accelera-tors for increased combustion temperature. These materials areavailable in appropriate purity and form from carbon analyzervendors. The criter
39、ion for satisfactory results is the absence ofsignificant additional carbon release upon recombustion of thespecimen.8.8 Silica GelDesiccant for the desiccator.8.9 Oxygen Carrier Gas99.999 % purity with inlet pres-sure 350 to 500 kPa (g) or as specified by the manufacturer.9. Reference Materials9.1
40、The calibration of the analyzer is made by measuringmaterials with carbon content in the range of concentrationexpected in the MOX pellet traceable to a reference materialfrom a national standards body such as the U.S. NationalInstitute for Standards and Technology (NIST) or equivalent.Suitable non-
41、matrix matched materials traceable to a referencematerial in steel matrices (steel pins, steel rings, steel granules,and steel powder) ranging from 5 to 1500 g carbon/g sampleare available and have been found satisfactory. Matrix matchedreference materials for MOX pellets are not available.10. Preca
42、utions10.1 Because of the toxicity of plutonium, all operationsshould be performed within an approved glove box fitted withappropriate filters to contain any small particle of plutonium.Adetailed discussion of the necessary precautions is beyond thescope of this test method. Personnel involved in th
43、ese analysesshould be familiar with safe handling practices.10.2 The furnace, sample tube, and sample crucibles areheated to 1600C. Extreme care must be exercised to avoidburns or injury by quartz in a glove box and to avoid breachingthe primary confinement boundary. Care should be taken toavoid con
44、tacting gloves with hot surfaces. Typically these hotsurfaces are guarded and inaccessible during the heatingprocess and therefore do not pose a risk to the operator.10.3 Exercise appropriate caution when working with com-pressed gases.10.4 This procedure uses hazardous chemicals. Use appro-priate p
45、recautions for handling corrosives, oxidizers, andgases.11. Preparation and Verification of Apparatus Prior toSample Analysis11.1 Turn on the analyzer and set the operating controls ofthe instrument system according to the operating instructionsfor the specific equipment used.11.2 Verification of th
46、e GasesCarrier gas flow and systempressure are two essential parameters that must be controlled toensure satisfactory performance of the instrument. Most ana-lyzers are equipped with pressure regulation and electronicflow control.11.2.1 Ensure that the regulator valve is set to the correctvalue for
47、the oxygen line per manufacturersrecommendations.11.2.2 The following gas pressure parameters should bechecked during the analysis and are often automatically moni-tored by the gas analyzer software: gas pressure when thefurnace is opening, gas pressure during leak test and gas flowduring analysis.1
48、1.3 Verification of the ReagentsChange instrument col-umn packing and reagents as recommended by manufacturer.11.3.1 The sodium hydroxide changes color from dark tolight gray due to the reaction with CO2. It should be replacedwhen approximately half of the reagent tube has turned to alight gray colo
49、r.11.3.2 The cellulose should be replaced when approxi-mately13 of it has turned to a brown or black color.11.3.3 Replace the magnesium perchlorate when approxi-mately half of the contents of the reagent tube have beenconsumed due to absorbed water.11.3.4 The platinized silica in the oxidation furnace regen-erates itself in the oxygen carrier gas. However, due to possiblecontamination it should be replaced approximately semi-annually, or based on use.11.3.5 At regular intervals and at each replace of thereagents, the O-rings at the reagent tube
