1、Designation: C 787 06Standard Specification forUranium Hexafluoride for Enrichment1This standard is issued under the fixed designation C 787; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in pa
2、rentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers uranium hexafluoride (UF6)intended for feeding to an enrichment plant. Included arespecifications for UF6derived from un
3、irradiated natural ura-nium and UF6derived from irradiated uranium that has beenreprocessed and converted to UF6for enrichment and subse-quent reuse. The objectives of this specification are twofold:(1) To define the impurity and uranium isotope limits forCommercial Natural UF6feedstock so that the
4、correspondingenriched uranium is essentially equivalent to enriched uraniummade entirely from virgin natural UF6; and (2) To defineadditional limits for Reprocessed UF6(or any mixture ofReprocessed UF6and Commercial Natural UF6). For suchUF6, special provisions may be needed to ensure that no extrah
5、azard arises to the work force, process equipment, or theenvironment.1.2 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-vance of this specification does not relieve the us
6、er of theobligation to conform to all international, federal, state, andlocal regulations for processing, shipping, or in any other wayusing UF6(see, for example, TID-7016, DP-532, ORNL-NUREG-CSD-6, and DOE O 474.1).1.3 The values stated in SI units are to be regarded as thestandard. The values give
7、n in parentheses are for informationonly.2. Referenced Documents2.1 ASTM Standards:2C 761 Test Methods for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and Radiochemical Analysis ofUranium HexafluorideC 859 Terminology Relating to Nuclear Materials3C 996 Specification for Uranium Hexafluor
8、ide Enriched toLess Than 5 %235UC 1052 Practice for Bulk Sampling of Liquid UraniumHexafluorideC 1295 Test Method for Gamma Energy Emission fromFission Products in Uranium Hexafluoride and UranylNitrate Solution2.2 ANSI Standard:N14.1 Packaging of Uranium Hexafluoride for Transport42.3 U.S. Governme
9、nt Documents:Inspection, Weighing, and Sampling of Uranium Hexafluo-ride Cylinders, Procedures for Handling and Analysis ofUranium Hexafluoride, Vol. 1, Department of EnergyReport ORO-671-1, latest revision5The UF6Manual: Good Handling Practices for UraniumHexafluoride, United States Enrichment Corp
10、oration Re-port USEC-651, latest revision6Nuclear Safety Guide, U.S. Nuclear Regulatory CommissionReport TID-7016, Rev. 2, 1978, and ORNL-NUREG-CSD-65Clarke, H. K., Handbook of Nuclear Safety, Department ofEnergy Report DP-5325Control and Accountability of Nuclear Materials, DOEDirective O 474.153.
11、Terminology3.1 Definitions of Terms Specific to This StandardTermsshall be defined in accordance with Terminology C 859, exceptfor the following:3.1.1 Commercial Natural UF6UF6from natural unirra-diated uranium (containing 0.711 6 0.004 g235U per 100 g U).3.1.1.1 DiscussionIt is recognized that some
12、 contamina-tion with reprocessed uranium may occur during routine1This specification is under the jurisdiction 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, 2006. Publishe
13、d February 2006. Originallyapproved in 1976. Last previous edition approved in 2003 as C 787 03e2.2For 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 Docu
14、ment Summary page onthe ASTM website.3Withdrawn.4Available from American National Standards Institute, 11 W. 42nd St., 13thFloor, New York, NY 10036.5Available from Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.6Available from United States Enrichment Corporation,
15、 6903 Rockledge Drive,Bethesda, MD 20817.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.processing. This is acceptable provided that the UF6meets therequirements for Commercial Natural UF6.3.1.2 Reprocessed UF6any UF6made from urani
16、um thathas been exposed in a neutron irradiation facility and subse-quently chemically separated from the fission products andtransuranic isotopes so generated.3.1.2.1 DiscussionThe requirements for Reprocessed UF6given in this specification are intended to be typical ofreprocessed spent fuel that h
17、as achieved burnup levels of up to50,000 MWD/Metric tonne days per tonne of uranium in lightwater reactors and has been cooled for ten years after dis-charge. It is recognized that different limits would be necessaryto accommodate different fuel histories.4. Safety, Health Physics, and Criticality R
18、equirements4.1 The UF6concentration shall be not less than 99.5 g UF6per 100 g of sample in order 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
19、psia at 200F), or862 kPa at 112C (125 psia at 235F)Additionally, if a measurement is taken over solid UF6, thenthe vapor 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,
20、 air, or other volatile components that might causeoverpressure when heating the shipping container to obtain aliquid sample or withdraw the contents.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
21、exclusion of these materials isto prevent a vigorous reaction with UF6upon heating. It isessential that contamination of the UF6containers, such as byvacuum pump oil, be prevented since it is not practical toobtain a sample without heating the UF6. For fully substitutedchlorofluorocarbons a maximum
22、limit may be agreed uponbetween the parties concerned. An alternative means of dem-onstrating compliance with this requirement, other than bydirect measurement, may be agreed upon between the partiesconcerned.4.4 For Reprocessed UF6the gamma radiation from fissionproducts shall not exceed 1.1 3 105M
23、eV Bq/kgU (1.1 3 105MeV/sec kgU). The measurements are made in accordancewith Test Method C 1295 or equivalent. The purpose of thisrequirement is to limit the gamma dose from fission products towhich plant workers might be exposed to a level less than 20 %of the gamma dose from aged natural uranium,
24、 and to limit thequantity of fission products in effluent from enrichment andfuel fabrication plants.4.5 For Reprocessed UF6, the alpha activity from neptunium(Np) and plutonium (Pu) isotopes may be specified in either oftwo ways as agreed upon between the parties concerned:4.5.1 The total alpha act
25、ivity from Np and Pu in the cylindershall be limited to 25 000 Bq/kgU (1.5 3 106disintegrationsper minute per kilogram of uranium). This criterion is con-cerned with both the volatile components and those that remainon the inner surfaces and in the heel, so it can be measuredpractically only by samp
26、ling from the inflow during the fillingof the shipping container; or4.5.2 The volatile alpha activity from Np and Pu in theliquid sample from the shipping container shall be limited to3300 Bq/kgU (0.2 3 106disintegrations per minute per kilo-gram of uranium). To prevent nonvolatile particles from be
27、ingincluded in this measurement, the liquid sample must befiltered through a porous nickel filter as described in TestMethods C 761.5. Chemical, Physical, and Isotopic Requirements5.1 Plants preparing UF6will have to control the purity ofprocess chemicals and also employ low corrosion equipment tobe
28、 successful in meeting the specifications for most impurities.Both Commercial Natural UF6and Reprocessed UF6will haveto meet the same specification criteria for most elements. Inaddition, Reprocessed UF6must meet additional specificationlimits for artificially created radioactive species. For evalua
29、tingCommercial Natural UF6, the measured concentration of236Uwill be used as an indicator for contamination with reprocesseduranium, on the assumption that there is no opportunity forcontamination with irradiated uranium that has not beenprocessed to remove the majority of fission products. Provided
30、that this isotope does not exceed the concentration limit forCommercial Natural UF6listed in 5.5, the expected concentra-tions of artificial isotopes would be so far below normaldetection limits that measurements to determine compliancewith the separate limits are not appropriate. Uranium hexafluo-r
31、ide that fails to meet Commercial Natural UF6limits wouldrequire further testing to determine its acceptability as Repro-cessed UF6.5.2 The UF6content shall be reported as gUF6/100 ofsample.5.3 The total of all the following listed elements that formnonvolatile fluorides, having a vapor pressure of
32、101.3 kPa orless at 300C (1 atm or less at 572F) shall not exceed 300 g/gof uranium:aluminum iron sodiumarsenic iron sodiumbarium lead strontiumberyllium lithium thoriumbismuth magnesium tincadmium manganese zinccalcium nickel zirconiumchromium potassiumcopper silver5.3.1 If the concentration of an
33、impurity element is given asa less-than value (this is a concentration expressed as being lessthan the lower detection limit of the analytical method), thisless-than value shall be taken as the concentration of thatelement in determining the total impurity content.5.4 The volatile component of the f
34、ollowing elements shallnot exceed the values listed below:Element Value, g/g of uraniumantimony 1arsenic 3 (see Note 1)boron 1bromine 5C787062chlorine 100chromium 10 (see Note 1)molybdenum 1.4niobium 1phosphorus 50ruthenium 1silicon 100tantalum 1titanium 1tungsten 1.4vanadium 1.4NOTE 1Total chromium
35、 and total arsenic are usually expected to bewell below 10g/gU and 3g/gU, respectively. If the total value of theelement (noted hereafter as E(total) is found to be above the limit in 5.4,the volatile component may be determined by either of the followingtechniques as described in Test Method C 761:
36、by measuring the insoluble component of the Element, and deducing thevolatile component by: Evolatile!5 Etotal!2 Enonvolatile!5 Etotal!2Einsoluble!or, by vapor transfer of a sample UF6(taken according to PracticeC 1052) from its original sample container to a new container. Measuringthe Element in t
37、he hydrolysed UF6of the new container will yield thevolatile component of the Element initially present, providing the transferhas been made in the vapor phase Evolatile!5 Etotal!2 Enonvolatile!5Eafter gas transfer!If E(total)exceeds the value in 5.4, then agreement in advance betweenthe parties (fo
38、r example, suppler, receiver) shall be required to accept thematerial.5.5 Minor IsotopesThese items shall not exceed the limitsgiven as micrograms per gram of total uranium (g/gU).Commercial Natural UF6Reprocessed UF6232U 0.00001 0.005234U 62 480.0236U 20 8400.05.5.1 It is recognized that variabilit
39、y in natural uraniumdoes occur and affects the234U level.234U levels in the rangeof 5662 g/gU have been identified in a small part of naturaluranium production. For compliance with Specification C 996after enrichment, a234U content of 56 g/gU or less inCommercial Natural UF6is generally required to
40、yield En-riched Commercial Grade UF6that does not exceed 10.0 3103g234U/g235U (Specification C 996 requires agreement inadvance between the parties to accept Enriched CommercialGrade UF6above 10.0 3 103g234U/g235U).A234U content of5762 g/gU will yield Enriched Commercial Grade UF6thatmay exceed this
41、 level, but will generally comply with the limitin Specification C 996 of 11.0 3 103g234U/g235U. Therefore,prior to any delivery of Commercial Natural UF6containing234U above 56 g/gU,the234U level shall be reported and shall require agreement inadvance between the parties (for example, converter, en
42、richer)to accept the material.5.5.2 Values at or below the above limit for232UinCommercial Natural UF6may be assumed without measure-ment provided that it can be demonstrated that the materialmeets the236U limits.5.5.3 For Commercial Natural UF6, isotopic concentrationsshall be reported for234U,235U
43、, and236U unless it can beotherwise demonstrated that the UF6conforms to the appro-priate isotopic specifications (for example, through the sellersquality assurance records). For Commercial Natural UF6fromverifiable virgin natural uranium sources the analysis of236Uisnot normally required unless oth
44、erwise agreed upon betweenthe buyer and seller.5.5.4 Unirradiated UF6at any235U concentration other thanthat of Commercial Natural UF6might be delivered as feedmaterial if this is acceptable to the enricher. Renegotiation ofthe impurity limits may be needed under these circumstances.5.5.5 For Reproc
45、essed UF6, isotopic concentrations shall bemeasured and reported for232U,234U,235U, and236U.5.6 Technetium99Tc shall not exceed the following limitsgiven as micrograms per gram of total uranium (g/gU).Commercial Natural UF6Reprocessed UF699Tc 0.001 0.5005.6.1 For Commercial Natural UF6from verifiabl
46、e (forexample, through the sellers quality assurance records) virginnatural uranium sources, the analysis of99Tc is not normallyrequired unless otherwise agreed upon between the buyer andseller.5.6.2 For Reprocessed UF6the concentration of99Tc shallbe measured and reported.6. Sampling6.1 A represent
47、ative sample of sufficient size to perform thetests prescribed shall be taken while the material is liquid andhomogeneous. Relevant sample procedures are given in Prac-tice C 1052, USEC Report USEC-651, and DOE ReportORO-671-1.6.2 All samples shall be clearly identified including thesellers lot numb
48、er.6.3 All containers used for a lot shall be positively identifiedas containing material from a particular homogeneous lot.7. Methods of Chemical and Isotopic Analysis7.1 Chemical and isotopic analysis shall conform to TestMethods C 761, or demonstrated equivalent, as mutuallyagreed upon between th
49、e buyer and seller.8. Packaging, Handling, and Shipping8.1 Procedures for packaging, handling, and shipping UF6are given in ANSI N14.1, USEC Report USEC-651, and DOEReport ORO-671-1, or appropriate national or internationalprocedures.8.2 Cylinders used for Reprocessed UF6traffic shall not beused for Commercial Natural UF6unless decontaminatedinternally before filling with Commercial Natural UF6. Theheels in cylinders that have contained Reprocessed UF6maycontain significant levels of gamma emitters such as232Udaughters. The resulting gam
