1、Designation: C922 14Standard Specification forSintered Gadolinium Oxide-Uranium Dioxide Pellets1This standard is issued under the fixed designation C922; 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 forgadolinium oxide-uranium dioxide pellets
3、. 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 reactor s
4、ystems. 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 oxi
5、de-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 comm
6、ercial 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 the
7、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 allinternational
8、, 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 pr
9、ecautionary 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 andhealth
10、 practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C753 Specification for Nuclear-Grade, Sinterable UraniumDioxide PowderC859 Terminology Relating to Nuclear MaterialsC888 Specification for Nuclear-Grade Gadolinium Oxide(Gd2O3)
11、 PowderC968 Test Methods for Analysis of Sintered GadoliniumOxide-Uranium Dioxide PelletsC996 Specification for Uranium Hexafluoride Enriched toLess Than 5 %235UE105 Practice for Probability Sampling of Materials2.2 ANSI Standard:3ANSI/ASME NQA-1 Quality Assurance Requirements forNuclear Facility Ap
12、plications2.3 U.S. Government Documents:4Code of Federal Regulations (Latest Edition), Title 10, Part50, Domestic Licensing of Production and UtilizationFacilitiesCode of Federal Regulations, Title 10, Part 71, Packagingand Transportation of Radioactive Material1This specification is under the juris
13、diction of ASTM Committee C26 onNuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.02 on Fueland Fertile Material Specifications.Current edition approved Jan. 1, 2014. Published February 2014. Originallyapproved in 1983. Last previous edition approved in 2008 as C922 08. DOI:10.
14、1520/C0922-14.2For 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 to the standards Document Summary page onthe ASTM website.3Available from American National Standards Ins
15、titute (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 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.gpo.gov/fdsys/browse/collectionCfr.action?collectionCode-CFR.Copyright A
16、STM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Code of Federal Regulations, Title 49, Part 173, ShippersGeneral Requirements for Shipments and PackagingsRegulatory Guide 1.126, An Acceptable Model and RelatedStatistical Methods for theAnalysis
17、of Fuel Densification,current version53. Terminology3.1 DefinitionsFor definitions of terms, refer to Terminol-ogy C859.4. Technical Requirements4.1 Major ConstituentsGadolinium oxide-uranium diox-ide pellets shall be fabricated using major constituents thatmeet the requirements of Specifications C7
18、53 and C888.4.2 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 C968 (latest edition) ordemonstrated equivalent as mutually agreed to betwee
19、n theseller and the buyer.4.2.1 Impurity ContentThe impurity content shall notexceed the individual element 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 U. If an element analysis is r
20、eported as “less than”a given concentration, this “less than” value shall be used in thedetermination of total impurities. The thorium measurementsrequired by Table 1 may be waived, provided that the seller canotherwise demonstrate compliance with this specification, forinstance, through the sellers
21、 quality assurance records.4.2.2 StoichiometryThe oxygen-to-metal ratio of sinteredfuel pellets shall be within the range from 1.98 to 2.02.4.2.3 Moisture ContentThe moisture content limit is in-cluded in the total hydrogen limit (see Table 1).4.2.4 Gd2O3ConcentrationThe gadolinium oxide(Gd2O3) conc
22、entration shall be as specified in the purchaseorder.4.3 Nuclear Requirements:4.3.1 Isotopic Content: For (U,Gd)O2pellets with an isoto-pic content of235U between that of natural uranium and 5 %,the isotopic limits of Specification C996 shall apply, unlessotherwise agreed upon between the buyer and
23、the seller. If the236U content is greater than enriched commercial grade UF6requirements, the isotopic analysis requirements of Specifica-tion C996 shall apply. The specific isotopic measurementsrequired by Specification C996 may be waived, provided thatthe seller can otherwise demonstrate complianc
24、e with Specifi-cation C996, for instance, through the sellers quality assurancerecords. A236U content greater than the one specified inSpecification C996 for Commercial grade UF6may be agreedupon between the buyer and the seller.64.3.2 For (U,Gd)O2pellets not having an assay in the rangeset forth in
25、 4.3.1, the isotopic requirements shall be as agreedupon between the buyer and the seller.4.4 Physical Characteristics:4.4.1 DimensionsThe dimensions of the pellet shall be asspecified by the buyer. These shall include diameter, length,perpendicularity, and, as required, other geometric parametersin
26、cluding surface finish.4.4.2 Pellet DensityThe density of sintered pellets shall beas specified by the buyer. The theoretical density for UO2ofnatural 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 an
27、d the seller.7Densitymeasurements shall be made by the method stated in Specifi-cation C753 for the geometric method, an immersion densitytechnique, 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
28、,Gd)O2fuel pellets may be affected by the grain size andpore morphology. These characteristics shall be mutuallyagreed upon between the buyer and the seller.4.4.4 Pellet HomogeneityThe homogeneity of Gd2O3inUO2shall be determined for the sintered pellets by a procedureand to a standard and specifica
29、tion mutually agreed uponbetween the buyer and the seller. The characteristics to bemeasured in order to verify this homogeneity (for instance, thefractions of Gd2O3,UO2, and UO2/Gd2O3solid solutionregions, or the maximum particle size of Gd2O3and UO2particles or any other characteristic representat
30、ive of thehomogeneity of the pellets) shall be defined by agreementbetween the buyer and the seller, and their values shall be asspecified.4.4.5 Pellet IntegrityPellets shall be inspected to criteriawhich maintain adequate fuel performance and ensure thatexcessive breakage will not occur during fuel
31、-rod loading.Acceptable test methods include a visual (1) comparison withpellet standards or other methods, for example, loadabilitytests, approved by both the buyer and the seller.4.4.5.1 Surface CracksThe suggested limits for surfacecracks are defined as follows:5Available from U.S. Nuclear Regula
32、tory Commission, Washington, DC 20555.Attention: Director, Division of Document Control, http:/www.nrc.gov.6The intent of the C996 isotopic limits is to indicate possible presence ofreprocessed UF6. Acceptance of (U,Gd)O2pellets with236U content above thatspecified for Enriched Commercial Grade UF6,
33、 shall be based on fuel performanceevaluation.7X-ray diffraction studies may be 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
34、/cm3and 7.41 g/cm3values for the density of Gd2O3have been used forthis interpolation.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)
35、1.3Iron 500Nickel 250Nitrogen 75Silicon 500Thorium 10C922 142(1) Axial Cracks, including those leading to the PelletEnds12 the pellet length.(2) Circumferential Cracks13 of the pellet circumfer-ence.4.4.5.2 ChipsThe limits for chips (missing material) are asfollows:(1) Cylindrical Surface Chips(a)Cy
36、lindrical 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 betweenthe buyer and t
37、he 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 grinding media.4.6
38、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 allowance for sucheffec
39、ts 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 Guide1.126 or (b ) by adequate correlation of manufacturing processor microstructure to in-reactor behavior, or both.5. Lot R
40、equirements5.1 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 Conformance to this spe
41、cification 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 lot. Practice E105 is
42、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 sample shall be of sufficient size to performquality assurance testing by the seller, referee t
43、ests 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. The referee sample shall
44、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 shall be conducted by techn
45、iques 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 make available uponrequ
46、est 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 be contingent upon the m
47、aterial 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 dioxide pellets shall bep
48、ackaged 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 th
49、e 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,8.2.5 Nominal gadolinium oxide (Gd2O3) concentration,weight %,8.2.6 Distinctive cautionary marking for presence of aneutron absorber,8.2.7 Gross, tare, and net oxide weights,8.2.8 Uranium weight,8.2.9 Purchase order number, and8.2.10 Container ( ) of ( ).9. Quality Assurance9.1 Quality assurance requirements shall be agree
