1、Designation: C776 17Standard Specification forSintered Uranium Dioxide Pellets for Light Water Reactors1This standard is issued under the fixed designation C776; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis specification is intended to provide the nuclear industry with a general standard for uraniumdioxide (UO2) pellets for lig
3、ht water reactor use. It recognizes the diversity of manufacturing methodsby which UO2pellets are produced and the many special requirements for chemical and physicalcharacterization which may be imposed by the operating conditions to which the pellets will besubjected in different light water react
4、ors. Therefore, it is anticipated that the purchaser maysupplement this specification with additional requirements for specific applications.1. Scope1.1 This specification is for finished sintered UO2pellets. Itapplies to UO2pellets containing uranium (U) of any235Uconcentration for use in nuclear r
5、eactors.1.2 This specification recognizes the presence of repro-cessed U in the fuel cycle and consequently defines isotopiclimits for UO2pellets made from commercial grade UO2. Suchcommercial grade UO2is defined so that, regarding fuel designand manufacture, the product is essentially equivalent to
6、 thatmade from unirradiated U. UO2falling outside these limitscannot necessarily be regarded as equivalent and may thusneed special provisions at the fuel fabrication plant or in thefuel design.1.3 This specification does not include (a) provisions forpreventing criticality accidents, (b) requiremen
7、ts for health andsafety, (c) avoidance of hazards, or (d) shipping precautionsand controls. Observance of this specification does not relievethe user of the obligation to be aware of and conform to allfederal, state, and local regulations pertaining to possessing,shipping, processing, or using sourc
8、e or special nuclear mate-rial. Examples of U.S. Government documents are Code ofFederal Regulations (Latest Edition), Title 10, Part 50, Title 10,Part 70, Title 10, Part 71, and Title 49, Part 173.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are inc
9、luded in thisstandard.1.5 The following precautionary caveat pertains only to thetechnical requirements portion, Section 4, of this specification:This standard does not purport to address all of the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard
10、 to establish appropriate safety,health, and environmental practices and determine the appli-cability or regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Prin
11、ciples 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:2C696 Test Methods for Chemical, Mass Spectrometric, andSpectrochemical Analysis of Nuclear-Gr
12、ade Uranium Di-oxide Powders and PelletsC753 Specification for Nuclear-Grade, Sinterable UraniumDioxide PowderC859 Terminology Relating to Nuclear MaterialsC996 Specification for Uranium Hexafluoride Enriched toLess Than 5 %235UC1233 Practice for Determining Equivalent Boron Contentsof Nuclear Mater
13、ialsE105 Practice for Probability Sampling of MaterialsE112 Test Methods for Determining Average Grain Size1This specification is under the jurisdiction of ASTM Committee C26 onNuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.02 on Fueland Fertile Material Specifications.Curre
14、nt edition approved Nov. 1, 2017. Published November 2017. Originallyapproved in 1976. Last previous edition approved in 2011 as C776 06 (2011).DOI: 10.1520/C0776-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual B
15、ook 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 Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recog
16、nized 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.12.2 ASME Standard:3ASME NQA-1 QualityAssurance Requirements for
17、NuclearFacility Applications2.3 U.S. Government Documents:Code of Federal Regulations (Latest Edition), Title 10, Part50 Domestic Licensing of Production and Utilization Fa-cilities4Code of Federal Regulations, Title 10, Part 70 DomesticLicensing of Special Nuclear Material4Code of Federal Regulatio
18、ns, Title 10, Part 71 Packagingand Transportation of Radioactive Material4Code of Federal Regulations, Title 49, Part 173 GeneralRequirements for Shipments and Packaging4Regulatory Guide NUREG 1.126 An Acceptable Model andRelated Statistical Methods for the Analysis of FuelDensification, Rev. 1 Marc
19、h 197853. Terminology3.1 DefinitionsFor definitions of terms, refer to Terminol-ogy C859.4. Technical Requirements4.1 Chemical RequirementsAll chemical analyses shall beperformed on portions of the representative sample prepared inaccordance with Section 6. Analytical chemistry methods usedshall be
20、as stated in Test Methods C696 (latest edition) ordemonstrated equivalent as mutually agreed upon between theseller and the buyer.4.1.1 Uranium ContentThe U content shall be a minimumof 87.7 weight % on a dry weight basis. (Dry weight is definedas the sample weight minus the moisture content.)4.1.2
21、Impurity ContentThe impurity content shall notexceed the individual element limit specified in Table 1 onaUweight basis. The summation of the contribution of each of theimpurity elements listed in Table 1 shall not exceed 1500 g/g.If an element analysis is reported as “less than” a givenconcentratio
22、n, this “less than” value shall be used in thedetermination of total impurities.4.1.3 StoichiometryThe oxygen-to-uranium ratio of sin-tered fuel pellets shall be within the range from 1.99 to 2.02.4.1.4 Moisture ContentThe moisture content limit is in-cluded in the total hydrogen limit (see Table 1)
23、.4.2 Nuclear Requirements:4.2.1 Isotopic Content:4.2.1.1 For UO2pellets with an isotopic content of235Ubelow 5 %, the isotopic limits of Specification C996 shallapply, unless otherwise agreed upon between the buyer and theseller. If the236U content is greater than the Enriched Com-mercial Grade UF6r
24、equirements, the isotopic analysis require-ments of Specification C996 shall apply. The specific isotopicmeasurements required by Specification C996 may be waived,provided that the seller can demonstrate compliance withSpecification C996, for instance, through the sellers qualityassurance records.4.
25、2.1.2 For UO2pellets not having an assay in the range setforth in 4.2.1.1, the isotopic requirements shall be as agreedupon between the buyer and the seller.4.2.2 Equivalent Boron ContentFor light water reactoruse, the total equivalent boron content (EBC) shall not exceed4.0 g/g on a U basis. The to
26、tal EBC is the sum of theindividual EBC values. For purpose of EBC calculation B, Gd,Eu, Dy, Sm, and Cd shall be included in addition to elementslisted in Table 1. The method of performing the calculationshall be as indicated in Practice C1233. For fast reactor use, theabove limitation on EBC does n
27、ot apply.4.3 Physical Characteristics:4.3.1 DimensionsThe dimensions of the pellet and theirtolerances shall be specified by the buyer. These shall includediameter, length, perpendicularity, and, as agreed upon be-tween the buyer and seller, other parameters including end-faceconfiguration and surfa
28、ce finish. The diameter can be deter-mined by three (3) multiple-point measurements at a minimum:middle and the two extremities of the pellet. Length measure-ments shall be made between the furthest extremities of thepellet on the land area.4.3.2 Pellet DensityThe density and tolerance of sinteredpe
29、llets shall be as specified by the buyer. The theoreticaldensity (TD) for UO2shall be considered as 10.96 g/cm3.Density measurements shall be made by the method stated inSpecification C753 (for the geometric method), by an immer-sion density technique, or by demonstrated equivalent methodas mutually
30、 agreed upon between the buyer and the seller, orcombinations thereof.4.3.3 Grain Size and Pore Size DistributionBecause thereis no unique structure for ensuring satisfactory performance,the pellet grain size and pore size distribution shall be mutuallyagreed upon between the buyer and the seller. T
31、he mean grainsize can be measured as described in Test Method E112 orequivalent.4.3.4 Pellet IntegrityPellets shall be inspected and sortedto criteria which maintain adequate fuel performance andensure general pellet integrity during subsequent handling.3Available from American Society of Mechanical
32、 Engineers (ASME), ASMEInternational Headquarters, Two Park Ave., New York, NY 10016-5990, http:/www.asme.org.4Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.5Available from U.S. Nuclea
33、r Regulatory Commission, Washington, DC 20555.Attention: Director, Division of Document Control.TABLE 1 Impurity Elements and Maximum Concentration LimitsElementMaximum ConcentrationLimit (g/g U)Aluminum (Al) 250Carbon (C) 100Calcium (Ca) + magnesium (Mg) 200Chlorine (Cl) 25Chromium (Cr) 250Cobalt (
34、Co) 100Fluorine (F) 15Hydrogen (H, total from all sources) 1.3Iron (Fe) 500Nickel (Ni) 250Nitrogen (N) 75Silicon (Si) 500Thorium (Th) 10C776 172Acceptable inspection methods include lateral surface inspec-tion using automated equipment, a visual (1) comparison withpellet standards, or other methods,
35、 as mutually agreed uponbetween the buyer and the seller. Surface defects to beinspected for include chips, cracks, pits, end-capping, lips,inclusions, unground surfaces, blisters, spots/discoloration, andprotrusions. Specific acceptance criteria and limits relative tothe above characteristics shall
36、 be mutually agreed upon be-tween the buyer and seller.4.3.5 Cleanliness and WorkmanshipThe surfaces of fin-ished pellets shall be visually free of macroscopic inclusionsand foreign material such as oil and grinding media.4.4 IdentificationPellets may be identified as to enrich-ment by either markin
37、g or coding.4.5 Irradiation Stability (Densification)An estimate of thefuel pellet irradiation stability shall be obtained (maximumdensification anticipated) unless adequate allowance for sucheffects is factored into the fuel rod design. The estimate of thestability shall consist of either (a) confo
38、rmance to the thermalstability test as specified in the applicable US NRC RegulatoryGuide NUREG 1.126, or (b) equivalent test or qualificationmethod as agreed upon between the buyer and the seller. Suchmethods typically consist of resintering the pellets at around1700C for a minimum of 24 hours and
39、calculating the densitychange. The mean density change must be positive and belowa certain threshold to be accepted, for example less than 2 % ofthe TD. Pellet density determination shall be performed asindicated in 4.3.2.5. Lot Requirements5.1 A pellet lot is defined as a group of pellets made from
40、 asingle UO2powder lot as defined in Specification C753 usingone set of process parameters.5.2 The identity of a pellet lot shall be retained throughoutprocessing without mixing with other established lots.5.3 Conformance to this specification shall be establishedfor each pellet lot.6. Sampling6.1 U
41、O2pellets may be hygroscopic and retain water afterexposure to a moist atmosphere. Sampling and handling thesample shall be done under conditions which assure that thesample is representative of the lot. Practice E105 is referencedas a guide.6.2 The buyer shall have the option to take a representati
42、vesample of pellets from each pellet lot for the purpose ofdetermining chemical, nuclear, or physical properties.6.3 The lot sample shall be of sufficient size to performquality assurance testing and referee testing in the event itbecomes necessary, and, when required, acceptance testing atthe buyer
43、s plant.6.4 The lot sample for acceptance testing at the buyersplant, when required, shall be packaged in a separate container,clearly identified by lot number, and shall be shipped precedingthe shipment or with the lot.6.5 The referee sample shall be clearly identified andretained by the manufactur
44、er per requirements established bythe buyer.7. Testing and Certification7.1 The seller shall sample pellets as described in Section 6to assure conformance of the pellet lot to the requirements ofSection 4. All testing shall be conducted by techniques mutu-ally agreed to between the buyer and the sel
45、ler (and manufac-turer if different from the seller).7.2 The seller shall provide to the buyer documentationcertifying that the pellets meet all the requirements of Section4.7.3 For a time period to be agreed upon by the buyer and theseller, the seller shall maintain and make available uponrequest a
46、ll results used to certify that pellets meet the require-ments of Section 4.7.4 Lot AcceptanceAcceptance testing may be performedby the buyer on either the sample provided by the seller or ona sample taken at the buyers plant. Acceptance shall be on apellet lot basis and shall be contingent upon the
47、 materialproperties meeting the requirements of Section 4, or modifiedSection 4 by contract documentation.7.5 RefereeThe buyer and seller shall agree to a thirdparty as a referee in the event of a dispute in analytical results.8. Packaging and Shipping8.1 UO2pellets shall be packaged in sealed conta
48、iners toprevent loss or damage of material and contamination fromairborne or container materials. The exact size and type ofpackaging shall be mutually agreed upon between the buyerand the seller.8.2 Each container in 8.1 shall bear labels on the lid and sidethat include the required information to
49、satisfy the appropriatetransportation and regulatory requirements, including as aminimum the following:8.2.1 Sellers name,8.2.2 Material in container,8.2.3 Lot number,8.2.4 U enrichment,8.2.5 Gross, tare, net oxide weights,8.2.6 U weight,8.2.7 Purchase order number, and8.2.8 Container ( ) of ( ) (total number of containers).9. Quality Assurance9.1 Quality assurance requirements shall be agreed uponbetween the buyer and the seller when specified in the purchaseorder. Code of Federal Regulations Title 10, Part 50,AppendixB and ASME NQA-1 are refer
