Standard Specification for Sintered Uranium Dioxide Pellets

ABSTRACT
This specification covers sintered uranium dioxide pellets containing 235U for use in nuclear reactors. Chemical requirements include uranium content, impurity content, stoichiometry, and moisture content. Maximum concentration limits are specified for impurity elements such as: aluminum, carbon, calcium+magnesium, chlorine, chromium, cobalt, fluorine, hydrogen, iron, nickel, nitrogen, silicon, and thorium. Chemical analyses shall be performed. Nuclear requirements include isotopic content and equivalent boron content. The following are physical characteristics of the material: dimensions, pellet density, grain size and pore morphology, pellet integrity–surface cracks and chips, and cleanliness and workmanship. Fuel pellet irradiation stability shall be estimated. Pellet lot shall be retained throughout processing without mixing with other established lots.
SCOPE
1.1 This specification is for finished sintered uranium dioxide pellets. It applies to uranium dioxide pellets containing uranium of any  235U concentration for use in nuclear reactors.
1.2 This specification recognizes the presence of reprocessed uranium in the fuel cycle and consequently defines isotopic limits for uranium dioxide pellets made from commercial grade UO2. Such commercial grade UO2 is defined so that, regarding fuel design and manufacture, the product is essentially equivalent to that made from unirradiated uranium. UO2 falling outside these limits cannot necessarily be regarded as equivalent and may thus need special provisions at the fuel fabrication plant or in the fuel design.  
1.3 This specification does not include  (a) provisions for preventing criticality accidents or  (b) requirements for health and safety. Observance of this specification does not relieve the user 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. Examples of U.S. Government documents are Code of Federal Regulations (Latest Edition), Title 10, Part 50, Title 10, Part 71, and Title 49, Part 173.
1.4 The following precautionary caveat pertains only to the technical requirements portion, Section 4, of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability or regulatory limitations prior to use.

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ASTM C776-06(2011) - Standard Specification for Sintered Uranium Dioxide Pellets
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:C776 −06 (Reapproved 2011)
Standard Specification for
Sintered Uranium Dioxide Pellets
This standard is issued under the fixed designation C776; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This specification is intended to provide the nuclear industry with a general specification for
uranium dioxide pellets. It recognizes the diversity of manufacturing methods by which uranium
dioxide pellets are produced and the many special requirements for chemical and physical
characterization which may be imposed by the operating conditions to which the pellets will be
subjected in specific reactor systems. Therefore, it is anticipated that the purchaser may supplement
this specification with additional requirements for specific applications.
1. Scope health practices and determine the applicability or regulatory
limitations prior to use.
1.1 This specification is for finished sintered uranium diox-
ide pellets. It applies to uranium dioxide pellets containing
235 2. Referenced Documents
uranium of any U concentration for use in nuclear reactors.
2.1 ASTM Standards:
1.2 This specification recognizes the presence of repro-
C696Test Methods for Chemical, Mass Spectrometric, and
cessed uranium in the fuel cycle and consequently defines
SpectrochemicalAnalysis of Nuclear-Grade Uranium Di-
isotopiclimitsforuraniumdioxidepelletsmadefromcommer-
oxide Powders and Pellets
cialgradeUO .SuchcommercialgradeUO isdefinedsothat,
2 2
C753Specification for Nuclear-Grade, Sinterable Uranium
regarding fuel design and manufacture, the product is essen-
Dioxide Powder
tially equivalent to that made from unirradiated uranium. UO
C859Terminology Relating to Nuclear Materials
falling outside these limits cannot necessarily be regarded as
C996Specification for Uranium Hexafluoride Enriched to
equivalent and may thus need special provisions at the fuel
Less Than 5 % U
fabrication plant or in the fuel design.
C1233Practice for Determining Equivalent Boron Contents
1.3 This specification does not include (a) provisions for
of Nuclear Materials
preventing criticality accidents or (b) requirements for health
E105Practice for Probability Sampling of Materials
andsafety.Observanceofthisspecificationdoesnotrelievethe
2.2 ANSI Standard:
useroftheobligationtobeawareofandconformtoallfederal,
ANSI/ASME NQA-1Quality Assurance Requirements for
state, and local regulations pertaining to possessing, shipping,
Nuclear Facility Applications
processing, or using source or special nuclear material. Ex-
2.3 U.S. Government Documents:
amples of U.S. Government documents are Code of Federal
Code of Federal Regulations (Latest Edition), Title 10,Part
Regulations(LatestEdition),Title10,Part50,Title10,Part71,
50, Energy (10 CFR 50) Domestic Licensing of Produc-
and Title 49, Part 173.
tion and Utilization Facilities
1.4 The following precautionary caveat pertains only to the
Code of Federal Regulations,Title 10, Part 71, Packaging
technical requirements portion, Section 4, of this specification:
and Transportation of Radioactive Material
This standard does not purport to address all of the safety
concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
This specification is under the jurisdiction of ASTM Committee C26 on the ASTM website.
NuclearFuelCycleandisthedirectresponsibilityofSubcommitteeC26.02onFuel Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
and Fertile Material Specifications. 4th Floor, New York, NY 10036, http://www.ansi.org.
Current edition approved June 1, 2011. Published June 2011. Originally AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments,
approved in 1976. Last previous edition approved in 2006 as C776–06. DOI: 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
10.1520/C0776-06R11. www.access.gpo.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C776−06 (2011)
Code of Federal Regulations,Title 49, Part 173, General andtheseller .Thespecificisotopicmeasurementsrequiredby
Requirements for Shipments and Packaging SpecificationC996maybewaived,providedthatthesellercan
Regulatory Guide NUREG 1.126AnAcceptable Model and demonstrate compliance with Specification C996, for instance,
Related Statistical Methods for the Analysis of Fuel through the seller’s quality assurance records.
Densification, Rev. 1 March 1978 4.2.1.2 For UO pellets not having an assay in the range set
forth in 4.2.1.1, the isotopic requirements shall be as agreed
3. Terminology
upon between the buyer and the seller.
4.2.2 Equivalent Boron Content—For thermal reactor use,
3.1 Definitions—For definitions of terms, refer to Terminol-
the total equivalent boron content (EBC) shall not exceed 4.0
ogy C859.
µg/g on a uranium basis. The total EBC is the sum of the
individualEBCvalues.ForpurposeofEBCcalculationB,Gd,
Eu, Dy, Sm, and Cd shall be included in addition to elements
TABLE 1 Impurity Elements and Maximum Concentration Limits
listed in Table 1 below. The method of performing the
Maximum Concentration
Element
calculation shall be as indicated in Practice C1233. For fast
Limit (µg/g U)
reactor use, the above limitation on EBC does not apply.
Aluminum 250
Carbon 100
4.3 Physical Characteristics:
Calcium + magnesium 200
4.3.1 Dimensions—The dimensions of the pellet shall be
Chlorine 25
Chromium 250
specified by the buyer. These shall include diameter, length,
Cobalt 100
perpendicularity, and, as required, other geometric parameters
Fluorine 15
including surface finish.
Hydrogen (total from all sources) 1.3
Iron 500
4.3.2 Pellet Density—Thedensityofsinteredpelletsshallbe
Nickel 250
as specified by the buyer. The theoretical density for UO of
Nitrogen 75
natural isotopic content shall be considered as 10.96 g/cm .
Silicon 500
Thorium 10
Density measurements shall be made by the geometric method
stated in the Specification C753Annex, an immersion method
or by a demonstrated equivalent method as mutually agreed
upon between the buyer and the seller.
4.3.3 Grain Size and Pore Morphology—The performance
4. Technical Requirements
of UO fuel pellets may be affected by the grain size and pore
4.1 Chemical Requirements—Allchemicalanalysesshallbe
morphology. These characteristics shall be mutually agreed
performedonportionsoftherepresentativesamplepreparedin
upon between the buyer and the seller.
accordance with Section 6.Analytical chemistry methods used
4.3.4 Pellet Integrity—Pellets shall be inspected to criteria
shall be as stated in Test Methods C696 (latest edition) or
which maintain adequate fuel performance and ensure that
demonstrated equivalent as mutually agreed upon between the
excessive breakage will not occur during fuel-rod loading.
seller and the buyer.
Acceptabletestmethodsincludeavisual(1×)comparisonwith
4.1.1 Uranium Content—The uranium content shall be a
pellet standards or other methods, for example, loadability
minimumof87.7weight%onadryweightbasis.(Dryweight
tests, approved by both the buyer and the seller.
is defined as the sample weight minus the moisture content.)
4.3.4.1 Surface Cracks—The suggested limits for surface
4.1.2 Impurity Content—The impurity content shall not
cracks are defined as follows:
exceed the individual element limit specified in Table 1 on a
(1) Axial Cracks, including those leading to the Pellet
uranium weight basis. The summation of the co
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