ASTM C787-2011 Standard Specification for Uranium Hexafluoride for Enrichment《浓缩用六氟化铀标准规格》.pdf

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1、Designation: C787 11Standard Specification forUranium Hexafluoride for Enrichment1This standard is issued under the fixed designation C787; 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 pare

2、ntheses indicates the year of last reapproval. Asuperscript epsilon () 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 unirr

3、adiated 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 cor

4、respondingenriched 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 extrahaza

5、rd 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 user

6、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 given i

7、n parentheses are for informationonly.2. Referenced Documents2.1 ASTM Standards:2C761 Test Methods for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and Radiochemical Analysis ofUranium HexafluorideC859 Terminology Relating to Nuclear MaterialsC996 Specification for Uranium Hexafluoride Enr

8、iched toLess Than 5 %235UC1052 Practice for Bulk Sampling of Liquid UraniumHexafluorideC1295 Test Method for Gamma Energy Emission fromFission Products in Uranium Hexafluoride and UranylNitrate SolutionC1703 Practice for Sampling of Gaseous UraniumHexafluoride2.2 ANSI Standard:N14.1 Packaging of Ura

9、nium Hexafluoride for Transport32.3 U.S. Government 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 revision4The UF6Manual: Good Handling Practices for U

10、raniumHexafluoride, United States Enrichment Corporation Re-port USEC-651, latest revision5Nuclear Safety Guide, U.S. Nuclear Regulatory CommissionReport TID-7016, Rev. 2, 1978, and ORNL-NUREG-CSD-64Clarke, H. K., Handbook of Nuclear Safety, Department ofEnergy Report DP-5324Control and Accountabili

11、ty of Nuclear Materials, DOEDirective O 474.143. Terminology3.1 Definitions of Terms Specific to This StandardTermsshall be defined in accordance with Terminology C859, exceptfor the following:3.1.1 Commercial Natural UF6UF6from natural unirra-diated uranium (containing 0.711 6 0.004 g235U per 100 g

12、 U).3.1.1.1 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 UF6.1This specification is under the jurisdiction of ASTM Committee C26 onNuclear Fuel Cyc

13、le and is the direct responsibility of Subcommittee C26.02 on Fueland Fertile Material Specifications.Current edition approved June 1, 2011. Published July 2011. Originally approvedin 1976. Last previous edition approved in 2006 as C787 06. DOI: 10.1520/C0787-11.2For referenced ASTM standards, visit

14、 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, 11 W. 42nd St., 13thFloor, New York, NY 100

15、36.4Available from Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.5Available from United States Enrichment Corporation, 6903 Rockledge Drive,Bethesda, MD 20817.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, Unit

16、ed States.3.1.2 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.3.1.2.1 DiscussionThe requirements for Reprocessed UF6given in this specification are i

17、ntended to be typical ofreprocessed spent fuel that has achieved burnup levels of up to50 000 Megawatt days per tonne of uranium in light waterreactors and has been cooled for ten years after discharge. It isrecognized that different limits would be necessary to accom-modate different fuel histories

18、.4. Safety, Health Physics, and Criticality Requirements4.1 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

19、 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 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 pre

20、ssure check is to limit the hydrogenfluoride, 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 exc

21、eed 0.01 mol %of the UF6. The reason for the exclusion of these materials isto prevent a vigorous reaction with UF6upon heating or withstronger-fluorinating agents which may be present in enrich-ment plants. It is essential that contamination of the UF6containers, such as by vacuum pump oil, be prev

22、ented since itis not practical to obtain a sample without heating the UF6. Forfully substituted chlorofluorocarbons a maximum limit may beagreed upon between the parties concerned.4.3.1 Measures should be taken to minimize contaminationby hydrocarbons, chlorocarbons, and partially substituted ha-loh

23、ydrocarbons in the receiving cylinder before filling and it isgood practice to minimize such contact during UF6processing.4.3.2 If UF6has been liquefied, either during filling orduring sampling of the final shipping container, compliancecan be assumed. If the UF6has not been liquefied, compliancemus

24、t be demonstrated. An alternative means of demonstratingcompliance with this requirement, other than by direct mea-surement, may be agreed upon between the parties concerned.4.4 For Reprocessed UF6the gamma radiation from fissionproducts shall not exceed 1.1 3 105MeV Bq/kgU (1.1 3 105MeV/sec kgU). T

25、he measurements are made in accordancewith Test Method C1295 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, and to limit thequantity of fission

26、 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 activity from Np and Pu in the cylinder

27、shall 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 sampling from the inflow during the fill

28、ingof 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 beingincluded in this measurement, the

29、 liquid sample must befiltered through a porous nickel filter as described in TestMethods C761.5. Chemical, Physical, and Isotopic Requirements5.1 Plants preparing UF6will have to control the purity ofprocess chemicals and also employ low corrosion equipment tobe successful in meeting the specificat

30、ions 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 evaluatingCommercial Natural UF6, the measu

31、red 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. Providedthat this isotope does not exceed the

32、 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-ride that fails to meet Commercial Nat

33、ural UF6limits wouldrequire further testing to determine its acceptability as Repro-cessed UF6.5.2 The UF6content shall be reported as gUF6/100 g ofsample.5.3 The total of all the following listed elements that formnonvolatile fluorides, having a vapor pressure of 101.3 kPa orless at 300C (1 atm or

34、less at 572F) shall not exceed 300 g/gof uranium:aluminumarsenic iron sodiumbarium lead strontiumberyllium lithium thoriumbismuth magnesium tincadmium manganese zinccalcium nickel zirconiumchromium potassiumcopper silver5.3.1 If the concentration of an impurity element is given asa less-than value (

35、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.C787 1125.4 The volatile component of the following elements shallnot exceed the v

36、alues listed below:Element Value, g/g of uraniumantimony 1arsenic 3 (see Note 1)boron 1bromine 5chlorine 100chromium 10 (see Note 1)molybdenum 2 (see Note 1)niobium 1phosphorus 50ruthenium 1silicon 100tantalum 1titanium 1tungsten 2vanadium 2NOTE 1Total chromium, molybdenum, and arsenic are usually e

37、x-pected to be well below 10g/gU, 2g/gU, and 3g/gU, respectively. If thetotal value of the element (noted hereafter as E(total) is found to be abovethe limit in 5.4, the volatile component may be determined by either of thefollowing techniques as described in Test Method C761:by measuring the insolu

38、ble 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 PracticeC1052) from its original sample container to a new container. Measuringthe Element in the hydrolysed UF6of the

39、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 (for example, suppler, rece

40、iver) 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 62 480.0 (see Note 2)236U 20 8400.05.5.1 It is recognized that variability in natura

41、l 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 C996after enrichment, a234U content of 56 g/gU or less inCommercial Natural UF6is generally required to yield En-ric

42、hed Commercial Grade UF6that does not exceed 10.0 3103g234U/g235U (Specification C996 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 level, but w

43、ill generally comply with the limitin Specification C996 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, enricher)to acce

44、pt 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, and236U unle

45、ss 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 otherwise agreed

46、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 Reprocessed UF6, iso

47、topic concentrations shall bemeasured and reported for232U,234U,235U, and236U.NOTE 2If the234U level (expressed here in wt %) in reprocessed UF6exceeds the following limit: (0.036 3 wt %235U) 0.0004, then in orderto ensure compliance with Specification C996, an acceptance between theparties shall be

48、 required prior to any delivery. For example, for wt %235U= 1 %, then a value above 320 g234U/gU will require an acceptance.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 Comm

49、ercial Natural UF6from verifiable (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 representative 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 C1052, USEC Report USEC-651, and