1、Designation: C 922 08Standard Specification forSintered Gadolinium Oxide-Uranium Dioxide Pellets1This standard is issued under the fixed designation C 922; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis specification is intended to provide the nuclear industry with a general specification forgadolinium oxide-uranium dioxide pell
3、ets. It recognizes the diversity of manufacturing methods bywhich gadolinium oxide-uranium dioxide pellets are produced and the many special requirements forchemical and physical characterization that may be imposed by the operating conditions to which thepellets will be subjected in specific reacto
4、r systems. 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 gadoliniumoxide-uranium dioxide pellets for use in light-water reactors. Itapplies to gadolinium
5、oxide-uranium dioxide pellets contain-ing uranium of any235U concentration and any concentrationof gadolinium oxide.1.2 This specification recognizes the presence of repro-cessed uranium in the fuel cycle and consequently definesisotopic limits for gadolinium oxide-uranium dioxide pelletsmade from c
6、ommercial grade UO2. Such commercial gradeUO2is defined so that, regarding fuel design and manufacture,the product is essentially equivalent to that made from unirra-diated uranium. UO2falling outside these limits cannot neces-sarily be regarded as equivalent and may thus need specialprovisions at t
7、he fuel fabrication plant or in the fuel design.1.3 This specification does not include (1) provisions forpreventing criticality accidents or (2) requirements for healthand safety. Observance of this specification does not relieve theuser of the obligation to be aware of and conform to allinternatio
8、nal, federal, state, and local regulations pertaining topossessing, shipping, processing, or using source or specialnuclear material. Examples of U.S. Governmental documentsare Code of Federal Regulations (Latest Edition), Title 10, Part50, Title 10, Part 71, and Title 49, Part 173.1.4 The following
9、 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 to establish appropriate safety andhea
10、lth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 753 Specification for Nuclear-Grade, Sinterable UraniumDioxide PowderC 859 Terminology Relating to Nuclear Materials3C 888 Specification for Nuclear-Grade Gadolinium Oxide
11、(Gd2O3) PowderC 968 Test Methods for Analysis of Sintered GadoliniumOxide-Uranium Dioxide PelletsC 996 Specification for Uranium Hexafluoride Enriched toLess Than 5 %235UE 105 Practice for Probability Sampling Of Materials2.2 ANSI Standard:4ANSI/ASME NQA-1 Quality Assurance Requirements forNuclear F
12、acility Applications2.3 U.S. Government Documents:5Code of Federal Regulations (Latest Edition), Title 10, Part50, Energy (10 CFR 50) Domestic Licensing of Produc-tion and Utilization FacilitiesCode of Federal Regulations, Title 10, Part 71, Packagingand Transportation of Radioactive MaterialCode of
13、 Federal Regulations, Title 49, Part 173, GeneralRequirements for Shipments and Packaging1This 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 edition approve
14、d Jan. 1, 2008. Published February 2008. Originallyapproved in 1983. Last previous edition approved in 2000 as C 922 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer
15、 to the standards Document Summary page onthe ASTM website.3Withdrawn.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.5Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mai
16、l 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.Copyright by ASTM Intl (all rights reserved); Wed Nov 5 02:32:10 EST 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to Li
17、cense Agreement. No further reproductions authorized.Regulatory Guide NUREG 1.126, An Acceptable Modeland Related Statistical Methods for the Analysis of FuelDensification, Rev. 1 March 197863. Terminology3.1 DefinitionsFor definitions of terms, refer to Terminol-ogy C 859.4. Technical Requirements4
18、.1 Major ConstituentsGadolinium oxide-uranium diox-ide pellets shall be fabricated using major constituents thatmeet the requirements of Specifications C 753 and C 888.4.2 Chemical RequirementsAll chemical analyses shall beperformed on portions of the representative sample prepared inaccordance with
19、 Section 6. Analytical chemistry methods usedshall be as stated in Test Methods C 968 (latest edition) ordemonstrated equivalent as mutually agreed to between theseller and the buyer.4.2.1 Impurity ContentThe impurity content shall notexceed the individual element limit specified in Table 1 on auran
20、ium weight basis. The summation of the contribution ofeach of the impurity elements listed in Table 1 shall not exceed1500 g/g U. If an element analysis is reported as “less than”a given concentration, this “less than” value shall be used in thedetermination of total impurities. The thorium measurem
21、entsrequired by Table 1 may be waived, provided that the seller canotherwise demonstrate compliance with this specification, forinstance, through the sellers quality assurance records.4.2.2 StoichiometryThe oxygen-to-metal ratio of sin-tered fuel pellets shall be within the range from 1.98 to 2.02.4
22、.2.3 Moisture Content The moisture content limit isincluded in the total hydrogen limit (see Table 1).4.2.4 Gd2O3ConcentrationThe gadolinium oxide(Gd2O3) concentration shall be as specified in the purchaseorder.4.3 Nuclear Requirements:4.3.1 Isotopic Content:For (U,Gd)O2pellets with an isotopic cont
23、ent of235Ubetween that of natural uranium and 5 %, the isotopic limits ofSpecification C 996 shall apply, unless otherwise agreed uponbetween the buyer and the seller. If the236U content is greaterthan enriched commercial grade UF6requirements, the isotopicanalysis requirements of Specification C 99
24、6 shall apply. Thespecific isotopic measurements required by SpecificationC 996 may be waived, provided that the seller can otherwisedemonstrate compliance with Specification C 996, for instance,through the sellers quality assurance records. A236U contentgreater than the one specified in Specificati
25、on C 996 forCommercial grade UF6may be agreed upon between the buyerand the seller.74.3.2 For (U,Gd)O2pellets not having an assay in the rangeset forth in 4.3.1, the isotopic requirements shall be as agreedupon between the buyer and the seller.4.4 Physical Characteristics:4.4.1 DimensionsThe dimensi
26、ons of the pellet shall be asspecified by the buyer. These shall include diameter, length,perpendicularity, and, as required, other geometric parametersincluding surface finish.4.4.2 Pellet DensityThe density of sintered pellets shallbe as specified by the buyer. The theoretical density for UO2ofnat
27、ural isotopic content shall be considered to be 10.96 g/cm3.The theoretical density for the (U,Gd)O2shall be determined asagreed upon between the buyer and the seller.8Densitymeasurements shall be made by the method stated in Specifi-cation C 753 for the geometric method, an immersion densitytechniq
28、ue, or by a demonstrated equivalent method as mutuallyagreed upon between the buyer and the seller.4.4.3 Grain Size and Pore MorphologyThe performanceof (U,Gd)O2fuel pellets may be affected by the grain size andpore morphology. These characteristics shall be mutuallyagreed upon between the buyer and
29、 the seller.4.4.4 Pellet HomogeneityThe homogeneity of Gd2O3inUO2shall be determined for the sintered pellets by a procedureand to a standard and specification mutually agreed uponbetween the buyer and the seller. The characteristics to bemeasured in order to verify this homogeneity (for instance, t
30、hefractions of Gd2O3,UO2, and UO2/Gd2O3solid solutionregions, or the maximum particle size of Gd2O3and UO2particles or any other characteristic representative of thehomogeneity of the pellets) shall be defined by agreementbetween the buyer and the seller, and their values shall be asspecified.4.4.5
31、Pellet Integrity Pellets shall be inspected to criteriawhich maintain adequate fuel performance and ensure thatexcessive breakage will not occur during fuel-rod loading.Acceptable test methods include a visual (13) comparisonwith pellet standards or other methods, for example, loadabilitytests, appr
32、oved by both the buyer and the seller.4.4.5.1 Surface Cracks The suggested limits for surfacecracks are defined as follows:(1) Axial Cracks, including those leading to the PelletEnds12 the pellet length.6Available form U.S. Nuclear Regulatory Commission, Washington, DC 20555.Attention: Director, Div
33、ision of Document Control.7The intent of the C 996 isotopic limits is to indicate possible presence ofreprocessed UF6. Acceptance of (U,Gd)O2pellets with236U content above thatspecified for Enriched Commercial Grade UF6, shall be based on fuel performanceevaluation.8X-ray diffraction studies may be
34、used to establish the theoretical density of(U,Gd)O2. In lieu of x-ray diffraction data, the theoretical density of the (U,Gd)O2pellets is often taken as the molar interpolation of the values for UO2and Gd2O3.Both 8.33 g/cc and 7.41 g/cm3values for the density of Gd2O3have been used forthis interpol
35、ation.TABLE 1 Impurity Elements and Maximum Concentration LimitsElement Maximum Concentration Limit (g/g U)Aluminum 250Carbon 100Calcium + magnesium 200Chlorine 25Chromium 250Fluorine 15Hydrogen (total from all sources) 1.3Iron 500Nickel 250Nitrogen 75Silicon 500Thorium 10C922082Copyright by ASTM In
36、tl (all rights reserved); Wed Nov 5 02:32:10 EST 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.(2) Circumferential Cracks13 of the pellet circumfer-ence.4.4.5.2 ChipsThe limits for chips (missing material) areas follows:(1) Cylindrical S
37、urface Chips(a)Cylindrical Surface Areathe total area of all chips shall beless than 5% of the pellet cylindrical surface area.(b)Maximum Linear Dimensionthe maximum linear dimen-sion shall be established to maintain adequate fuel performancein the intended application and shall be agreed upon betwe
38、enthe buyer and the seller.(2) Pellet Ends13 of the pellet end surface (may beinspected as13 of missing circumference at the pellet end).4.5 Cleanliness and WorkmanshipThe surface of finishedpellets shall be visually free of loose chips, macroscopicinclusions, and foreign material such as oil and gr
39、inding media.4.6 Identification Pellets may be identified as to enrich-ment and gadolinia concentration by either marking or coding.4.7 Irradiation Stability (Densification)An estimate of thefuel pellet irradiation stability shall be obtained (maximumdensification anticipated) unless adequate allowa
40、nce 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 manufacturingprocess or microstructure to in-reactor beha
41、vior, or both.5. Lot Requirements5.1 A pellet lot is defined as a group of pellets made from asingle gadolinium oxide-uranium dioxide powder lot using oneset of process parameters.5.2 The identity of a pellet lot shall be retained throughoutprocessing without mixing with other established lots.5.3 C
42、onformance to this specification shall be establishedfor each pellet lot.6. Sampling6.1 Exposure of gadolinium oxide-uranium dioxide pelletsto moist or oxidizing atmospheres may cause detectable errors.Sample and handle the sample under conditions which assurethat the sample is representative of the
43、 lot. Practice E 105 isreferenced 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 sample shall be of sufficient size to performquality assurance testing b
44、y the seller, referee tests in the eventthey become necessary, and, when required, acceptance testingby the buyer.6.4 The lot sample for acceptance testing by the buyer,when required, shall be packaged in a separate container,clearly identified by lot number, and shipped preceding or withthe lot. Th
45、e referee sample shall be identified clearly andretained by the seller until the lot has been accepted formallyby the buyer.7. Testing and Certification7.1 The seller shall test the sample described in Section 6 toensure conformance of the pellet lot to the requirements ofSection 4. All testing shal
46、l be conducted by techniques mutu-ally agreed upon between the buyer and the seller.7.2 The seller shall provide to the buyer documentationcertifying that the pellets meet all requirements of Section 4.7.3 For a time period to be agreed upon by the buyer and theseller, the seller shall maintain and
47、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 by the seller or ona sample taken at the buyers plant. Acceptance shall be on alot basis and shall b
48、e contingent upon the material propertiesmeeting the requirements of Section 4 or as modified bycontract documentation.7.5 RefereeThe buyer and the seller shall agree to a thirdparty as a referee in the event of a dispute in analytical results.8. Packaging and Shipping8.1 Gadolinium oxide-uranium di
49、oxide pellets shall bepackaged in sealed containers to prevent loss or damage ofmaterial and contamination from airborne or container materi-als. The exact size and type of packaging shall be mutuallyagreed upon between the buyer and the seller.8.2 Each container in 8.1 shall bear labels on the lid and sidethat include the required information to 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 Nominal uranium enrichment,8.2
