1、Designation: C776 06 (Reapproved 2011)Standard Specification forSintered Uranium Dioxide Pellets1This 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 revision. A
2、 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 specification foruranium dioxide pellets. It recognizes
3、the diversity of manufacturing methods by which uraniumdioxide pellets 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 specific reactor systems. Therefore, it is anticip
4、ated that the purchaser may supplementthis specification with additional requirements for specific applications.1. Scope1.1 This specification is for finished sintered uranium diox-ide pellets. It applies to uranium dioxide pellets containinguranium of any235U concentration for use in nuclear reacto
5、rs.1.2 This specification recognizes the presence of repro-cessed uranium in the fuel cycle and consequently definesisotopic limits for uranium dioxide pellets made from commer-cial grade UO2. Such commercial grade UO2is defined so that,regarding fuel design and manufacture, the product is essen-tia
6、lly equivalent to that made from unirradiated uranium. UO2falling outside these limits cannot necessarily be regarded asequivalent and may thus need special provisions at the fuelfabrication plant or in the fuel design.1.3 This specification does not include (a) provisions forpreventing criticality
7、accidents or (b) requirements for healthand safety. Observance of this specification does not relieve theuser of the obligation to be aware of and conform to all federal,state, and local regulations pertaining to possessing, shipping,processing, or using source or special nuclear material. Ex-amples
8、 of U.S. Government documents are Code of FederalRegulations (Latest Edition), Title 10, Part 50, Title 10, Part 71,and Title 49, Part 173.1.4 The following precautionary caveat pertains only to thetechnical requirements portion, Section 4, of this specification:This standard does not purport to add
9、ress all of the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability or regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C696 Test Methods
10、 for Chemical, Mass Spectrometric, andSpectrochemical Analysis of Nuclear-Grade 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 %
11、235UC1233 Practice for Determining Equivalent Boron Contentsof Nuclear MaterialsE105 Practice for Probability Sampling of Materials2.2 ANSI Standard:3ANSI/ASME NQA-1 Quality Assurance Requirements forNuclear Facility Applications2.3 U.S. Government Documents:Code of Federal Regulations (Latest Editi
12、on), Title 10, Part50, Energy (10 CFR 50) Domestic Licensing of Produc-tion and Utilization Facilities4Code of Federal Regulations, Title 10, Part 71, Packagingand Transportation of Radioactive Material4Code of Federal Regulations, Title 49, Part 173, GeneralRequirements for Shipments and Packaging4
13、Regulatory Guide NUREG 1.126 AnAcceptable Model andRelated Statistical Methods for the Analysis of Fuel1This 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.Current e
14、dition approved June 1, 2011. Published June 2011. Originallyapproved in 1976. Last previous edition approved in 2006 as C776 06. DOI:10.1520/C0776-06R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMS
15、tandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4Available from U.S. Government Printing Office Superintendent of Documents,732
16、N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Densification, Rev. 1 March 197853. Terminology3.1 DefinitionsFor definitions of terms, refer to Termi
17、nol-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 as stated in Test Methods C696 (latest edition) ordemonstrated equivalent as
18、 mutually agreed upon between theseller and the buyer.4.1.1 Uranium ContentThe uranium content shall be aminimum of 87.7 weight % on a dry weight basis. (Dry weightis defined as the sample weight minus the moisture content.)4.1.2 Impurity ContentThe impurity content shall notexceed the individual el
19、ement limit specified in Table 1 on auranium weight basis. The summation of the contribution ofeach of the impurity elements listed in Table 1 shall not exceed1500 g/g. If an element analysis is reported as “less than” agiven concentration, this “less than” value shall be used in thedetermination of
20、 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).4.2 Nuclear Requirements:4.2.1 Isotopic Content:4.2.1.1 For U
21、O2pellets with an isotopic content of235Ubetween that of natural uranium and 5 %, the isotopic limitsand radionuclide analytical requirements of Specification C996shall apply, unless otherwise agreed upon between the buyerand the seller6. The specific isotopic measurements required bySpecification C
22、996 may be waived, provided that the seller candemonstrate compliance with Specification C996, for instance,through the sellers quality assurance records.4.2.1.2 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 an
23、d the seller.4.2.2 Equivalent Boron ContentFor thermal reactor use,the total equivalent boron content (EBC) shall not exceed 4.0g/g on a uranium basis. The total 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 eleme
24、ntslisted in Table 1 below. The method of performing thecalculation shall be as indicated in Practice C1233. For fastreactor use, the above limitation on EBC does not apply.4.3 Physical Characteristics:4.3.1 DimensionsThe dimensions of the pellet shall bespecified by the buyer. These shall include d
25、iameter, length,perpendicularity, and, as required, other geometric parametersincluding surface finish.4.3.2 Pellet DensityThe density of sintered pellets shallbe as specified by the buyer. The theoretical density for UO2ofnatural isotopic content shall be considered as 10.96 g/cm3.Density measureme
26、nts shall be made by the geometric methodstated in the Specification C753 Annex, an immersion methodor by a demonstrated equivalent method as mutually agreedupon between the buyer and the seller.4.3.3 Grain Size and Pore MorphologyThe performanceof UO2fuel pellets may be affected by the grain size a
27、nd poremorphology. These characteristics shall be mutually agreedupon between the buyer and the seller.4.3.4 Pellet IntegrityPellets shall be inspected to criteriawhich maintain adequate fuel performance and ensure thatexcessive breakage will not occur during fuel-rod loading.Acceptable test methods
28、 include a visual (13) comparisonwith pellet standards or other methods, for example, loadabilitytests, approved by both the buyer and the seller.4.3.4.1 Surface CracksThe suggested limits for surfacecracks are defined as follows:(1) Axial Cracks, including those leading to the PelletEnds12 the pell
29、et length.(2) Circumferential Cracks13 of the pellet circumfer-ence.4.3.4.2 ChipsThe limits for chips (missing material) areas follows:(1) Cylindrical Surface Chips(a)Cylindrical Surface Areathe total area of all chips shall beless than 5 % of the pellet cylindrical surface area.(b)Maximum Linear Di
30、mensionthe maximum linear dimen-sion shall be established to maintain adequate fuel performancein the intended application and shall be agreed upon betweenthe buyer and the seller.(2) Pellet Ends13 of the pellet end surface (may beinspected as13 of missing circumference at the pellet end).4.3.5 Clea
31、nliness and WorkmanshipThe surface 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 marking or coding.5Available from U.S. Nuclear Regulatory Commission, Wa
32、shington, DC 20555.Attention: Director, Division of Document Control.6A236U content greater than the one specified in Specification C996 forCommercial grade UF6may be acceptable for the intended application since it is nota radiological safety concern. The intent of the C996 isotope limits is to ind
33、icatepossible presence of reprocessed UF6. Acceptance of UO2pellets with a236Ucontent above that specified for Commercial Enriched UF6, shall be based on a fuelperformance evaluation.TABLE 1 Impurity Elements and Maximum Concentration LimitsElementMaximum ConcentrationLimit (g/g U)Aluminum 250Carbon
34、 100Calcium + magnesium 200Chlorine 25Chromium 250Cobalt 100Fluorine 15Hydrogen (total from all sources) 1.3Iron 500Nickel 250Nitrogen 75Silicon 500Thorium 10C776 06 (2011)24.5 Irradiation Stability (Densification)An estimate of thefuel pellet irradiation stability shall be obtained (maximumdensific
35、ation anticipated) unless adequate allowance for sucheffects is factored into the fuel rod design. The estimation ofthe stability shall consist of either (a) conformance to thethermal stability test as specified in US NRC Regulatory GuideNUREG 1.126,or(b) by adequate correlation of manufactur-ing pr
36、ocess or microstructure to in-reactor behavior, or both.5. Lot Requirements5.1 A pellet lot is defined as a group of pellets made from asingle uranium dioxide powder lot as defined in SpecificationC753 using one set of process parameters.5.2 The identity of a pellet lot shall be retained throughoutp
37、rocessing without mixing with other established lots.5.3 Conformance to this specification shall be establishedfor each pellet lot.6. Sampling6.1 Uranium dioxide pellets may be hygroscopic and retainsufficient water after exposure to a moist atmosphere. Sam-pling and handling the sample shall be don
38、e under conditionswhich assure that the sample is representative of the lot.Practice E105 is referenced as a guide.6.2 The buyer shall have the option to take a representativesample of pellets from each pellet lot for the purpose ofdetermining chemical, nuclear, or physical properties.6.3 The lot sa
39、mple shall be of sufficient size to performquality assurance testing at the sellers plant, referee testing inthe event it becomes necessary, and, when required, acceptancetesting at the buyers plant.6.4 The lot sample for acceptance testing at the buyersplant, when required, shall be packaged in a s
40、eparate container,clearly identified by lot number, and shipped preceding or withthe lot. The referee sample shall be clearly identified andretained at the sellers plant until the lot has been formallyaccepted by the buyer.7. Testing and Certification7.1 The seller shall test the sample described in
41、 Section 6 toassure 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 seller.7.2 The seller shall provide to the buyer documentationcertifying that the pellets meet all the requirements of Section
42、4.7.3 For a time period to be agreed upon by the buyer and theseller, the seller shall maintain and make available uponrequest all 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
43、by the seller or ona sample taken at the buyers plant. Acceptance shall be on apellet lot basis and shall be contingent upon the materialproperties meeting the requirements of Section 4 as modifiedby contract documentation.7.5 RefereeThe buyer and seller shall agree to a thirdparty as a referee in t
44、he event of a dispute in analytical results.8. Packaging and Shipping8.1 Uranium dioxide pellets shall be packaged in sealedcontainers to prevent loss or damage of material and contami-nation from airborne or container materials. The exact size andtype of packaging shall be as mutually agreed upon b
45、etweenthe buyer and the seller.8.2 Each container in 8.1 shall bear labels on the lid and sidethat include the required to satisfy the appropriate transporta-tion and regulatory requirements, including as a minimum thefollowing:8.2.1 Sellers name,8.2.2 Material in container,8.2.3 Lot number,8.2.4 Ur
46、anium enrichment,8.2.5 Gross, tare, net oxide weights,8.2.6 Uranium weight,8.2.7 Purchase order number, and8.2.8 Container ( ) of ( ).9. Quality Assurance9.1 Quality assurance requirements shall be agreed uponbetween the buyer and the seller when specified in the purchaseorder. Code of Federal Regul
47、ations Title 10, Part 50, AppendixB and ANSI/ASME NQA-1 are referenced as guides.10. Keywords10.1 nuclear fuel; nuclear fuel pellets; urania; uraniumdioxideC776 06 (2011)3APPENDIX(Nonmandatory Information)X1. PELLET LOADABILITY TESTX1.1 Randomly selected samples (the number of samplesto be establish
48、ed by statistical considerations) shall be sub-jected to an axial load representative of fuel rod loadingconditions at the fabrication plant. Each test sample shallconsist of ten finished pellets. Samples shall be subjected to anaxial load that is 125 % of the maximum load applied duringpellet loadi
49、ng without producing a chip with a maximum lineardimension in excess of that agreed upon between the buyer andseller.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must
