1、Designation: C776 06 (Reapproved 2011)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 revisi
2、on, the year of last revision. 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 specificationstandardfor
3、 uranium dioxide pellets.(UO2) pellets for light water reactor use. It recognizes the diversity ofmanufacturing methods by which uraniumUO2 dioxide pellets are produced and the many specialrequirements for chemical and physical characterization which may be imposed by the operatingconditions to whic
4、h the pellets will be subjected in specific reactor systems. different light waterreactors. Therefore, it is anticipated that the purchaser may supplement this specification withadditional requirements for specific applications.1. Scope1.1 This specification is for finished sintered uraniumUO2 dioxi
5、de pellets. It applies to uraniumUO2 dioxide pellets containinguranium (U) of any 235U concentration for use in nuclear reactors.1.2 This specification recognizes the presence of reprocessed uraniumU in the fuel cycle and consequently defines isotopiclimits for uraniumUO2 dioxide pellets made from c
6、ommercial grade UO2. Such commercial grade UO2 is defined so that, regardingfuel design and manufacture, the product is essentially equivalent to that made from unirradiated uranium.U. UO2 falling outsidethese limits cannot necessarily be regarded as equivalent and may thus need special provisions a
7、t the fuel fabrication plant or inthe fuel design.1.3 This specification does not include ( (a)a) provisions for preventing criticality accidents or accidents, ( (b)b) requirementsfor health and safety. safety, (c) avoidance of hazards, or (d) shipping precautions and controls. Observance of this sp
8、ecificationdoes not relieve the user of the obligation to be aware of and conform to all federal, state, and local regulations pertaining topossessing, shipping, processing, or using source or special nuclear material. Examples of U.S. Government documents are Codeof Federal Regulations (Latest Edit
9、ion), 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 as standard. No other units of measurement are included in this standard.1.5 The following precautionary caveat pertains only to the technical requirements porti
10、on, Section 4, of this specification: Thisstandard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the userof this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the applica
11、bilityor regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the Worl
12、d Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C696 Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Uranium DioxidePowders and PelletsC753 Specification for Nuclear-Grade, Sinterable Uranium Dio
13、xide Powder1 This specification is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.02 on Fuel and FertileMaterial Specifications.Current edition approved June 1, 2011Nov. 1, 2017. Published June 2011November 2017. Originally app
14、roved in 1976. Last previous edition approved in 20062011 asC776 06.C776 06 (2011). DOI: 10.1520/C0776-06R11.10.1520/C0776-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information,
15、refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all
16、 changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-295
17、9. United States1C859 Terminology Relating to Nuclear MaterialsC996 Specification for Uranium Hexafluoride Enriched to Less Than 5 % 235UC1233 Practice for Determining Equivalent Boron Contents of Nuclear MaterialsE105 Practice for Probability Sampling of MaterialsE112 Test Methods for Determining A
18、verage Grain Size2.2 ANSIASME Standard:3ANSI/ASMEASME NQA-1 Quality Assurance Requirements for Nuclear Facility Applications2.3 U.S. Government Documents:Code of Federal Regulations (Latest Edition), Title 10, Part 50 Part 50, Energy (10 CFR 50) Domestic Licensing of Productionand Utilization Facili
19、ties4Code of Federal Regulations, Title 10, Part 70 Domestic Licensing of Special Nuclear Material4Code of Federal Regulations, Title 10, Part 71 Title 10, Part 71, Packaging and Transportation of Radioactive Material4Code of Federal Regulations, Title 49, Part 173 Title 49, Part 173, General Requir
20、ements for Shipments and Packaging4Regulatory Guide NUREG 1.126 An Acceptable Model and Related Statistical Methods for the Analysis of Fuel Densification,Rev. 1 March 197853. Terminology3.1 DefinitionsFor definitions of terms, refer to Terminology C859.4. Technical Requirements4.1 Chemical Requirem
21、entsAll chemical analyses shall be performed on portions of the representative sample prepared inaccordance with Section 6. Analytical chemistry methods used shall be as stated in Test Methods C696 (latest edition) ordemonstrated equivalent as mutually agreed upon between the seller and the buyer.4.
22、1.1 Uranium ContentThe uraniumU content shall be a minimum of 87.7 weight % on a dry weight basis. (Dry weight isdefined as the sample weight minus the moisture content.)3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, Society of Mechanical Engineers (ASME),
23、ASME International Headquarters,Two Park Ave., New York, NY 10036, http:/www.ansi.org.10016-5990, http:/www.asme.org.4 Available 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.5 Available from U
24、.S. Nuclear Regulatory Commission, Washington, DC 20555. Attention: Director, Division of Document Control.TABLE 1 Impurity Elements and Maximum Concentration LimitsElement Maximum ConcentrationLimit (g/g U)Aluminum 250Carbon 100Calcium + magnesium 200Chlorine 25Chromium 250Cobalt 100Fluorine 15Hydr
25、ogen (total from all sources) 1.3Iron 500Nickel 250Nitrogen 75Silicon 500Thorium 10TABLE 1 Impurity Elements and Maximum Concentration LimitsElement Maximum ConcentrationLimit (g/g U)Aluminum (Al) 250Carbon (C) 100Calcium (Ca) + magnesium (Mg) 200Chlorine (Cl) 25Chromium (Cr) 250Cobalt (Co) 100Fluor
26、ine (F) 15Hydrogen (H, total from all sources) 1.3Iron (Fe) 500Nickel (Ni) 250Nitrogen (N) 75Silicon (Si) 500Thorium (Th) 10C776 1724.1.2 Impurity ContentThe impurity content shall not exceed the individual element limit specified in Table 1 on a uraniumUweight basis. The summation of the contributi
27、on of each of the impurity elements listed in Table 1 shall not exceed 1500 g/g.If an element analysis is reported as “less than” a given concentration, this “less than” value shall be used in the determinationof total impurities.4.1.3 StoichiometryThe oxygen-to-uranium ratio of sintered fuel pellet
28、s shall be within the range from 1.99 to 2.02.4.1.4 Moisture ContentThe moisture content limit is included in the total hydrogen limit (see Table 1).4.2 Nuclear Requirements:4.2.1 Isotopic Content:4.2.1.1 For UO2 pellets with an isotopic content of 235U between that of natural uranium and below 5 %,
29、 the isotopic limits andradionuclide analytical requirements of Specification C996 shall apply, unless otherwise agreed upon between the buyer and thesellerseller If the 236U content is greater than the Enriched Commercial Grade UF6 requirements, the isotopic analysisrequirements of Specification C9
30、96 shall apply. The specific isotopic measurements required by Specification C996 may bewaived, provided that the seller can demonstrate compliance with Specification C996, for instance, through the sellers qualityassurance records.4.2.1.2 For UO2 pellets not having an assay in the range set forth i
31、n 4.2.1.1, the isotopic requirements shall be as agreed uponbetween the buyer and the seller.4.2.2 Equivalent Boron ContentFor thermal light water reactor use, the total equivalent boron content (EBC) shall not exceed4.0 g/g on a uraniumU basis. The total EBC is the sum of the individual EBC values.
32、 For purpose of EBC calculation B, Gd,Eu, Dy, Sm, and Cd shall be included in addition to elements listed in Table 1 below. . The method of performing the calculationshall be as indicated in Practice C1233. For fast reactor use, the above limitation on EBC does not apply.4.3 Physical Characteristics
33、:4.3.1 DimensionsThe dimensions of the pellet and their tolerances shall be specified by the buyer. These shall includediameter, length, perpendicularity, and, as required, other geometric parameters including surface finish.agreed upon between thebuyer and seller, other parameters including end-fac
34、e configuration and surface finish. The diameter can be determined by three(3) multiple-point measurements at a minimum: middle and the two extremities of the pellet. Length measurements shall be madebetween the furthest extremities of the pellet on the land area.4.3.2 Pellet DensityThe density and
35、tolerance of sintered pellets shall be as specified by the buyer. The theoretical density(TD) for UO2 of natural isotopic content shall be considered as 10.96 g/cm3. Density measurements shall be made by the geometricmethod stated in the Specification C753 Annex, (for the geometric method), by an im
36、mersion method density technique, or by ademonstrated equivalent method as mutually agreed upon between the buyer and the seller.seller, or combinations thereof.4.3.3 Grain Size and Pore MorphologySize DistributionThe performance of UOBecause there is no2 fuel pellets may beaffected by the unique st
37、ructure for ensuring satisfactory performance, the pellet grain size and pore morphology. Thesecharacteristics size distribution shall be mutually agreed upon between the buyer and the seller. The mean grain size can bemeasured as described in Test Method E112 or equivalent.4.3.4 Pellet IntegrityPel
38、lets shall be inspected and sorted to criteria which maintain adequate fuel performance and ensure thatexcessive breakage will not occur during fuel-rod loading. Acceptable test methods include general pellet integrity duringsubsequent handling. Acceptable inspection methods include lateral surface
39、inspection using automated equipment, a visual (1)comparison with pellet standards, or other methods, for example, loadability tests, approved by both as mutually agreed uponbetween the buyer and the seller. Surface defects to be inspected for include chips, cracks, pits, end-capping, lips, inclusio
40、ns,unground surfaces, blisters, spots/discoloration, and protrusions. Specific acceptance criteria and limits relative to the abovecharacteristics shall be mutually agreed upon between the buyer and seller.4.3.4.1 Surface CracksThe suggested limits for surface cracks are defined as follows:(1) Axial
41、 Cracks, including those leading to the Pellet Ends12 the pellet length.(2) Circumferential Cracks13 of the pellet circumference.4.3.4.2 ChipsThe limits for chips (missing material) are as follows:(1) Cylindrical Surface Chips(a)Cylindrical Surface Areathe total area of all chips shall be less than
42、5 % of the pellet cylindrical surface area.(b)Maximum Linear Dimensionthe maximum linear dimension shall be established to maintain adequate fuel performance in theintended application and shall be agreed upon between the buyer and the seller.(2) Pellet Ends13 of the pellet end surface (may be inspe
43、cted as 13 of missing circumference at the pellet end).4.3.5 Cleanliness and WorkmanshipThe surfacesurfaces of finished pellets shall be visually free of macroscopic inclusionsand foreign material such as oil and grinding media.4.4 IdentificationPellets may be identified as to enrichment by either m
44、arking or coding.4.5 Irradiation Stability (Densification)An estimate of the fuel pellet irradiation stability shall be obtained (maximumdensification anticipated) unless adequate allowance for such effects is factored into the fuel rod design. The estimationestimateof the stability shall consist of
45、 either (a) conformance to the thermal stability test as specified in the applicable US NRC RegulatoryGuide NUREG 1.126, or (b) by adequate correlation of manufacturing process or microstructure to in-reactor behavior, orC776 173both.equivalent test or qualification method as agreed upon between the
46、 buyer and the seller. Such methods typically consist ofresintering the pellets at around 1700C for a minimum of 24 hours and calculating the density change. The mean density changemust be positive and below a certain threshold to be accepted, for example less than 2 % of the TD. Pellet density dete
47、rminationshall be performed as indicated in 4.3.2.5. Lot Requirements5.1 A pellet lot is defined as a group of pellets made from a single uraniumUO2 dioxide powder lot as defined in SpecificationC753 using one set of process parameters.5.2 The identity of a pellet lot shall be retained throughout pr
48、ocessing without mixing with other established lots.5.3 Conformance to this specification shall be established for each pellet lot.6. Sampling6.1 UraniumUO2 dioxide pellets may be hygroscopic and retain sufficient water after exposure to a moist atmosphere. Samplingand handling the sample shall be d
49、one under conditions which assure that the sample is representative of the lot. Practice E105is referenced as a guide.6.2 The buyer shall have the option to take a representative sample of pellets from each pellet lot for the purpose of determiningchemical, nuclear, or physical properties.6.3 The lot sample shall be of sufficient size to perform quality assurance testing at the sellers plant, and referee testing in theevent it becomes necessary, and, when required, acceptance testing at the buyers plant.6.4 The lot sample for acceptance te
