1、Designation: C 922 00Standard 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 unre-processed uranium. UO2falling outside these limits cannotnecessarily be regarded as equivalent and may thus needspecial provisions at th
7、e fuel fabrication plant or in the fueldesign.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 allinternationa
8、l, 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 p
9、recautionary 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 andhealt
10、h practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:C 696 Test Methods for Chemical, Mass Spectrometric, andSpectrochemical Analysis of Nuclear-Grade Uranium Di-oxide Powders and Pellets2C 753 Specification for Nuclear-Grade, Si
11、nterable UraniumDioxide Powder2C 859 Terminology Relating to Nuclear Materials2C 888 Specification for Nuclear-Grade Gadolinium Oxide(Gd2O3) Powder2C 968 Test Methods for Analysis of Sintered GadoliniumOxide-Uranium Dioxide Pellets2C 996 Specification for Uranium Hexafluoride Enriched toLess than 5
12、%235U2C 1233 Practice for Determining the Equivalent BoronContent of Nuclear Materials2E 105 Practice for Probability Sampling of Materials32.2 ANSI Standard:NQA-1 Quality Assurance Program Requirements forNuclear Facilities42.3 U.S. Government Documents:Code of Federal Regulations (Latest Edition),
13、 Title 10, Part50, Energy (10 CFR 50) Domestic Licensing of Produc-tion and Utilization Facilities5Code of Federal Regulations, Title 10, Part 71, Packagingand Transportation of Radioactive Material5Code of Federal Regulations, Title 49, Part 173, GeneralRequirements for Shipments and Packaging51Thi
14、s specification is under the jurisdiction of ASTM Committee C-26 onNuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.02 on Fueland Fertile Material Specifications.Current edition approved Jan. 10, 2000. Published March 2000. Originallypublished as C 922 83. Last previous editio
15、n C 922 94.2Annual Book of ASTM Standards, Vol 12.01.3Annual Book of ASTM Standards, Vol 14.02.4Available from the American National Standards Institute, 11 W. 42nd St., 13thFloor, New York, NY 10036.5Available from Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.1C
16、opyright ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.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
17、 C 859.4. Technical Requirements4.1 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
18、sample prepared inaccordance with 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 Content The impurity content shall notexceed the individual element l
19、imit 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 reported as “less than”a given concentration, this “less than” value shall be used in thedetermination of tota
20、l impurities. The thorium measurementsrequired 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 wi
21、thin the range from 1.98 to 2.02.4.2.3 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,
22、Gd)O2pellets with an isotopic content 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
23、requirements of Specification C 996 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.236U contentgreater than
24、one specified in Specification C 996 for Commer-cial grade UF6may be agreed between the buyer and the sellersince it is not a safety concern.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 selle
25、r.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 parametersincluding surface finish.4.4.2 Pellet Density The density of sintered pellets shallbe as s
26、pecified 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 determinedas agreed upon between the buyer and the seller.8Densitymeasurements shall be made by the method stated in Specifi-cation
27、C 753 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 behavior ofgadolinium oxide-uranium dioxide fuel pellets may be affectedby the grain size and pore mor
28、phology. These characteristicsshall be mutually agreed 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 specification mutually agreed uponbetween the buyer and the seller. The c
29、haracteristics 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 some combination there of, or any other charac-teristic representative of the homogeneity of the pe
30、llets) shallbe defined by agreement between the buyer and the seller, andtheir values shall be as specified.4.4.5 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 m
31、ethods include a visual (13) comparisonwith pellet standards or other methods, for example, loadabilitytests, approved 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 Pellet6Availab
32、le form U.S. Nuclear Regulatory Commission, Washington, DC 20555.Attention: Director, Division 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 G
33、rade UF6, shall be based on fuel performanceevaluation.8X-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.Bo
34、th 8.33 g/cc and 7.41 g/cc values for the density of Gd2O3have been used for thisinterpolation.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
35、sources) 1.3Iron 500Nickel 250Nitrogen 75Silicon 500Thorium 10C 9222Ends12 the pellet length.(2) Circumferential Cracks13 of the pellet circumference.4.4.5.2 ChipsThe limits for chips (missing material) areas follows:(1) Cylindrical Surface Chips(a)Cylindrical Surface Areathe total area of all chips
36、 shall beless than 5% of the pellet cylindrical surface area.(b)Maximum Linear Dimension30% of the pellet length.(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 visual
37、ly free of loose chips, macroscopicinclusions, and foreign material such as oil and grinding 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
38、 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) conformance to the thermalstability test as specified in US NRC Regulatory GuideNUREG 1.126 or (b)
39、by adequate correlation of manufacturingprocess 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 gadolinium oxide-uranium dioxide powder lot using oneset of process parameters.5.2 The identity of a pellet lot sha
40、ll be retained throughoutprocessing without mixing with other established lots.5.3 Conformance 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, weigh,
41、 and handle the sample under conditions whichassure that the sample is representative of the lot. Samplingplans to meet acceptance criteria shall be mutually agreed uponbetween the buyer and the seller. Practice E 105 is referencedas a guide.6.2 The buyer or his representative shall have the option
42、totake a representative sample of pellets from each pellet lot forthe purpose of determining chemical, nuclear, or physicalproperties.6.3 The lot sample shall be of sufficient size to performquality assurance testing by the seller, referee tests in the eventthey become necessary, and, when required,
43、 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 be identified clearly andretained by the seller until the l
44、ot 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 to the requirements of Section4. All testing shall be conducted by techniques mutually agreedupon between the buyer and the seller.7.2
45、The seller shall provide to the buyer documentationcertifying that the pellets meet all requirements of Section 4.7.3 When requested by the buyer, the seller shall makeavailable records of all data obtained from tests to certify thatpellets meet the requirements of Section 4.7.4 Lot AcceptanceAccept
46、ance 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 material propertiesmeeting the requirements of Section 4 or Section 4 as modifiedby contract documentation
47、.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 bepackaged in sealed containers to prevent loss or damage, orboth, of material and contamination f
48、rom airborne or containermaterials. The exact size and type of packaging shall bemutually agreed upon between the buyer and the seller.8.2 Each container in 8.1 shall bear labels on the lid and sidethat include the following information:8.2.1 Sellers name,8.2.2 Material in container,8.2.3 Lot number
49、,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 agreed uponbetween the buyer and the seller when specified in the purchaseorder. Code of Federal Regulations Title 10, Part 50, AppendixB and NQA-1 are referenced as guides.10. Keywords10.1 burnable poiso
