1、Designation: C996 15Standard Specification forUranium Hexafluoride Enriched to Less Than 5 %235U1This standard is issued under the fixed designation C996; 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.1. Scope1.1 This specification covers nuclear grade uraniumhexafluoride (UF6) that either has been processed through anenrichment plant, or has be
3、en produced by the blending ofHighly Enriched Uranium with other uranium to obtain ura-nium of any235U concentration below 5 % and that is intendedfor fuel fabrication. The objectives of this specification aretwofold: (1) To define the impurity and uranium isotope limitsfor Enriched Commercial Grade
4、 UF6so that, with respect tofuel design and manufacture, it is essentially equivalent toenriched uranium made from natural UF6; and (2) To definelimits for Enriched Reprocessed UF6to be expected if Repro-cessed UF6is to be enriched without dilution with CommercialNatural UF6. For such UF6, special p
5、rovisions, not definedherein, may be needed to ensure fuel performance and toprotect the work force, process equipment, and the environ-ment.1.2 This specification is intended to provide the nuclearindustry with a standard for enriched UF6that is to be used inthe production of sinterable UO2powder f
6、or fuel fabrication.In addition to this specification, the parties concerned mayagree to other appropriate conditions.1.3 The scope of this specification does not comprehen-sively cover all provisions for preventing criticality accidentsor requirements for health and safety or for shipping. Obser-va
7、nce of this specification does not relieve the user of theobligation to conform to all applicable international, federal,state, and local regulations for processing, shipping, or in anyother way using UF6(see, for example,TID-7016, DP-532, andDOE O474.1).1.4 The values stated in SI units are to be r
8、egarded as thestandard. The values given in parentheses are for informationonly.2. Referenced Documents2.1 ASTM Standards:2C761 Test Methods for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and RadiochemicalAnalysis ofUranium HexafluorideC787 Specification for Uranium Hexafluoride for Enri
9、ch-mentC859 Terminology Relating to Nuclear MaterialsC1052 Practice for Bulk Sampling of Liquid UraniumHexafluorideC1703 Practice for Sampling of Gaseous UraniumHexafluorideE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 ANSI/ASME Standards:3ASME
10、 NQA-1 QualityAssurance Requirements for NuclearFacility ApplicationsANSI N14.1 Nuclear MaterialsUranium HexafluoridePackaging for Transport2.3 U.S. Government Documents:Inspection, Weighing, and Sampling of Uranium Hexafluo-ride Cylinders, Procedure for Handling and Analysis ofUranium Hexafluoride,
11、 Vol. 1, DOE Report ORO-671-1,latest revision4Nuclear Safety Guide, U.S. NRC Report TID-7016, Rev. 2,1978Clarke, H. K., Handbook of Nuclear Safety, DOE ReportDP-5324Code of Federal Regulations, Title 10, Part 50, (AppendixB)41This specification is under the jurisdiction of ASTM Committee C26 onNucle
12、ar Fuel Cycle and is the direct responsibility of Subcommittee C26.02 on Fueland Fertile Material Specifications.Current edition approved July 1, 2015. Published July 2015. Originally approvedin 1983. Last previous edition approved in 2010 as C996 10. DOI: 10.1520/C0996-15.2For referenced ASTM stand
13、ards, 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 Institute (ANSI), 25 W. 43rd St.,4th Floor,
14、 New York, NY 10036.4Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.4 Other Document:The UF6Man
15、ual: Good Handling Practices for UraniumHexafluoride, United States Enrichment Corporation Re-port USEC-651, latest revision53. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 Terms shall be defined in accordance with Terminol-ogy C859 except for the following:3.1.2 Commercial Na
16、tural UF6UF6from natural unirra-diated uranium (containing 0.711 6 0.004 g235U per 100 g U).3.1.2.1 DiscussionIt is recognized that some contamina-tion with reprocessed uranium may occur during routineprocessing. This is acceptable provided that the UF6meets therequirements for Commercial Natural UF
17、6as specified inSpecification C787.3.1.3 Reprocessed UF6any UF6made from uranium thathas been exposed in a neutron irradiation facility and subse-quently chemically separated from the fission products andtransuranic isotopes so generated.3.1.4 Highly Enriched Uraniumany form of uraniumhaving a235U c
18、ontent of 20 % or greater.3.1.5 Enriched Commercial Grade UF6UF6enrichedfrom Commercial Natural UF6or Derived Enriched UF6thatmeets the specification limits for Enriched Commercial GradeUF6.3.1.6 Enriched Reprocessed UF6UF6enriched from Re-processed UF6, any mixture of Reprocessed UF6and Commer-cial
19、 Natural UF6or Derived Enriched UF6, exceeding theapplicable limits of Sections 4 and 5 for Enriched CommercialGrade UF6. The wide range of irradiation levels, cooling times,reprocessing, conversion, and enrichment processes, and fuelcycle choices for combination with unirradiated UF6, togetherwith
20、the varying acceptance limits of different fuel fabricationfacilities, make it not practical to specify the exact radionuclidecomposition of Enriched Reprocessed UF6.3.1.7 Derived Enriched UF6any UF6obtained from theblending of Highly Enriched Uranium with any other uranium.3.2 For enriched UF6trans
21、actions, “buyer” usually repre-sents the electric power utility company or the fuel fabricator,and “seller” usually represents the isotopic enrichment facility.4. Safety, Health Physics, and Criticality Requirements4.1 The UF6concentration shall not be less than 99.5 g UF6per 100 g of sample in orde
22、r to limit the potential hydrogencontent for nuclear criticality safety.4.2 The total absolute vapor pressure shall not exceed thevalues given below:380 kPa at 80C (55 psia at 176F), or517 kPa at 93C (75 psia at 200F), or862 kPa at 112C (125 psia at 235F)Additionally, if a measurement is taken over
23、solid UF6, thevapor pressure shall not exceed the values given below:50 kPa at 20C (7 psia at 68F), or69 kPa at 35C (10 psia at 95F)The purpose of the pressure check is to limit the hydrogenfluoride, air, or other volatile components that might causeoverpressure when heating the shipping container,
24、such as toobtain a liquid sample or withdraw the contents.4.2.1 If the temperature differs from 20C or 35C, atemperature correction must be performed which takes thechange in vapor pressure of UF6into account. For example, anacceptable correction would be that the pressure must remainbelow PUF6(T) +
25、 39.3 kPa, where PUF6(T) is the vapor pressureof pure UF6over solid at temperature T and PUF6(T) is givenaccording to Log PUF6= 12.77 (2562.46/T), with P in PascalandTinK.6Other methods or equations to assure that thepressure limits above are met are acceptable provided thatvalidated temperature com
26、pensation is made.4.3 The total hydrocarbon, chlorocarbon, and partially sub-stituted halohydrocarbon content shall not exceed 0.01 mol %of the UF6. The reason for the exclusion of these materials isto prevent a vigorous reaction with UF6upon heating. It isessential that contamination of the UF6cont
27、ainers, such as byvacuum pump oil, be prevented since it is not practical toobtain a sample without heating the UF6.An alternative meansof demonstrating compliance with this requirement, other thanby direct measurement, may be agreed upon between theparties concerned.4.3.1 Measures should be taken t
28、o minimize contaminationby hydrocarbons, chlorocarbons and halohydrocarbons in thereceiving cylinder before filling.4.3.2 Also, it is good practice to minimize contact ofhydrocarbon, chlorocarbon, and partially substituted halohy-drocarbon during UF6 processing.4.3.3 If UF6has been liquefied, either
29、 during filling orduring sampling of the final shipping container, compliancecan be assumed. If the UF6has not been liquefied, compliancemust be demonstrated. An alternative means of demonstratingcompliance with this requirement, other than by directmeasurement, may be agreed upon between the partie
30、s con-cerned.4.3.4 For fully substituted chlorofluorocarbons, a maximumlimit may be agreed upon between the parties concerned.4.4 For Enriched Commercial Grade UF6meeting the re-quirements of Section 5,(1) the gamma activity from fissionproducts is expected to be below the detection limits of themea
31、surement methodology; and (2) the alpha activity fromneptunium and plutonium is expected to be below the detectionlimits of commonly used measurement methodology. There-fore unless otherwise agreed upon between the buyer andseller, measurements are not required, except for DerivedEnriched UF6resulti
32、ng from blending with reprocessed ura-nium.4.5 For Enriched Reprocessed UF6, the gamma radiationfrom fission products shall not exceed 4.4 105MeVBq/kgU(4.4 105MeV/sec kgU).5Available from United States Enrichment Corporation, 6903 Rockledge Drive,Bethesda, MD 20817.6Comprehensive Nuclear Materials,
33、Volume 2, The U-F System, Ed. R.J.M.Konings, p. 209, Elsevier 2012.C996 1524.5.1 For Enriched Reprocessed UF6, the alpha activityfrom neptunium and plutonium shall be less than 3300 Bq/kgU(200 000 dpm/kgU).5. Chemical, Physical, and Isotopic Requirements5.1 Both Enriched Commercial Grade UF6and Enri
34、chedReprocessed UF6must meet the specification criteria except asdifferentiated in 4.4, 4.5, 5.4, and 5.5. For certain isotopes,including artificially created radioactive species, two groups oflimits are set. Limits for Enriched Commercial Grade UF6areset so as to have no special impact on the use o
35、f this materialin existing facilities. For Enriched Reprocessed UF6, higherlimits are indicated to correspond with Specification C787, andlower limits may be agreed upon by the buyer and selleraccording to the composition of the feed material presented forenrichment.5.2 The UF6content shall be repor
36、ted as gUF6/100 gsample.5.3 The following impurities shall not exceed these values:Element g/gUBoron 4Silicon 250For fully substituted chlorofluorocarbons a maximum limitmay be agreed upon between the parties concerned.5.4 Enriched Commercial Grade UF6shall comply with thelimits given in 5.5. For ev
37、aluating Enriched Commercial GradeUF6, the measured concentration of236U will be used as anindicator for contamination with reprocessed uranium, on theassumption that there is no opportunity for contamination withirradiated uranium that has not been processed to remove themajority of fission product
38、s. Uranium isotopic concentrationsshall be determined and reported for234U,235U, and236U.5.5 RadionuclidesThe following values represent limitsobtainable from the enrichment of UF6feed materials at thecorresponding limits of Specification C787. For purposes ofdetermining conformance with these limit
39、s, the observedvalues shall be rounded to the nearest significant digit indicatedin accordance with the rounding method of Practice E29. Forexample, for234U in Enriched Commercial Grade UF6theobserved value would be rounded to the nearest 0.1 103g234U/g235U.Enriched Commercial Grade UF6Enriched Repr
40、ocessed UF6232U 0.0001 g/gU, see 5.5.1, 5.5.2, and 5.5.3 0.050 g/gU, see Note 1234U 11.0103g/g235U, see Note 2 2000 g/gU, see Note 1236U 250 g/gU, see 5.5.3 see Note 199Tc 0.01 g/gU, see 5.5.4 5 g/gU, see Note 15.5.1 If the236U measurement result is less than 125 g/gU,then measurement of232U is not
41、required unless agreed uponbetween the buyer and seller.5.5.2 If the236U measurement result is greater than 125 butless than 250 g/gU, then measurement and reporting of232Uis required for routine acceptance of the UF6.5.5.3 The buyer may consider acceptance of the lot above250 g/gU on the basis of t
42、he total significance of all themeasured levels of radionuclides to determine the suitabilityfor intended use in the fuel fabrication and irradiation. Ifthe236U measurement result is greater than 250 g/gU, thenmeasurement of232U and notification of results before ship-ment are required.5.5.4 The buy
43、er and seller may agree to waive the require-ment to measure99Tc, provided that adequate capability tomeet the99Tc limit for Enriched Commercial grade UF6can bedemonstrated through quality assurance records. Such recordsshall include the results of the sellers periodic measurementsof99Tc in the UF6.
44、NOTE 1Enrichment of Reprocessed UF6feed material at the limit ofSpecification C787 could be expected to reach these limits. Defining theselimits does not imply that any fuel fabrication plant designed for EnrichedCommercial Grade UF6could handle Enriched Reprocessed UF6withoutdilution with Enriched
45、Commercial Grade UF6and other special precau-tions. With respect to the variability of Reprocessed UF6from various fuelhistories and the demands that would be placed on the fuel fabricators andusers, it could be necessary for the seller and buyer to agree on lowerlimits after enrichment than implied
46、 by Specification C787 feed limits.NOTE 2A234U content greater than 10.0 103g/g235U shall requireagreement in advance between the parties (for example, supplier, receiver)to accept the material. It is recognized that some applications may notallow for the limit in the table due to licensing, regulat
47、ory, or contractuallimitations.6. Sampling6.1 A representative sample of sufficient size to performtests prescribed shall be taken while the material is liquid andhomogeneous. Relevant sample procedures are given in Prac-tice C1052, USEC Report USEC-651, and DOE Report ORO-671-1.6.2 Alternatively, i
48、f the cylinder is filled in the gas phase, arepresentative sample may be taken during the transfer accord-ing to Practice C1703. It will have to be demonstrated that Gassampling is equivalent to Liquid sampling as representative ofthe bulk material in cylinder. Otherwise, the use of thisalternative
49、technique should be agreed between buyer andseller.6.3 All samples shall be clearly identified including thesellers lot number. It shall be stated whether samples havebeen taken in liquid or gas phase and whether they have beentaken during or after filling.6.4 All containers used for a lot shall be positively identifiedas containing material from a particular homogeneous lot.7. Test Methods for Chemical and Isotopic Analysis7.1 Chemical and isotopic analysis shall conform to TestMethods C761, or demonstrated equivalent, as mutually
