1、Designation: C 1346 02Standard Practice forDissolution of UF6from P-10 Tubes1This standard is issued under the fixed designation C 1346; 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 parenth
2、eses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the dissolution of UF6from a P-10tube to provide solutions for analysis.1.2 This standard does not purport to address all of thesa
3、fety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificsafeguard and safety precaution statements, see Section 8.2.
4、 Referenced Documents2.1 ASTM Standards:C 761 Test Methods for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and Radiochemical Analysis ofUranium Hexafluoride2C 787 Specification for Uranium Hexafluoride for Enrich-ment23. Summary of Practice3.1 UF6samples intended for analysis are packaged
5、 in P-10tubes to prevent sublimation and reaction with moisture in theair. The P-10 tube assembly (Fig. 1) consists of a fluorothenetube containing the UF6, a fluorothene gasket to cover thetubes opening, and a Monel nut and plug to seal the gasket tothe tube.3.2 The UF6tube is weighed, cooled in li
6、quid nitrogen, andquickly opened and immersed in ice-cold water for dissolution.The pieces of the tubes assembly are removed from theresulting solution, rinsed, dried, reassembled, and weighed.The solution is dried for gravimetric conversion to U3O8,ordiluted to an appropriate concentration for disp
7、ensing intoaliquants for subsequent analysis.4. Significance and Use4.1 Uranium hexafluoride is a basic material used to preparenuclear reactor fuel. To be suitable for this purpose the materialmust meet criteria for uranium content, isotopic composition,metallic impurities, hydrocarbon, and partial
8、ly substitutedhalohydrocarbon content in Specification C 787. This practiceresults in the complete dissolution of the sample for uraniumand impurities analysis, and determination of isotopic distribu-tion by thermal ionization mass spectrometry as described inTest Methods C 761. Highly volatile impu
9、rities should bedetermined directly on UF6.5. Apparatus5.1 Steam bath, in a hood, if optional step 9.2.13 is used.5.2 Vacuum oven, if option 2 of 9.2.16 is used. The ovenshould be adjustable to 80C at a pressure of -29 in. of Hg.5.3 Dewar flask, wide-mouth.5.4 Vise, small lab-bench model or similar
10、type of holder.5.5 Wrench,1516 in.5.6 Plastic clamping forceps, 12 to 13 cm long, with aclaw-like bent tip, to securely hold the cylindrical fluorothenetube.NOTE 1These forceps are not commercially available. Bend the endsof a straight-tip forceps by heating over a moderate flame, shaping, andmainta
11、ining the shape until cool.5.7 TFE-fluorocarbon-coated spatula, 0.5- to 1-cm wide atits flat end, optional.5.8 Platinum or fluorothene rod, optional.5.9 Platinum dishes, large enough to contain a completelysubmerged P-10 tube.5.10 Copper wires, optional. The wires should be flexibleand looped at one
12、 end to loosely fit around the fluorothene tubewithout allowing the Monel flare nut to pass through.1This practice is under the jurisdiction of ASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved Jan. 10, 2002. Pu
13、blished April 2002. Originallypublished as C 134696. Last previous edition C 1346962Annual Book of ASTM Standards, Vol 12.01.NOTE 1This figure is from page 10 of the reference in Footnote 4.FIG. 1 P-10 Sample Tube1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, P
14、A 19428-2959, United States.5.11 Desiccator. optional.5.12 Balance, $100-g capacity, readable to at least 0.1 mg,preferably 0.01 mg.NOTE 2Use of a balance with lower sensitivity will negatively impacton sampling error.6. Interferences6.1 The weight of the fluorothene tube is affected byatmospheric h
15、umidity. Keep the P-10 tube assembly in adesiccator between weighings until constant weight is attained.6.2 The capacity of the UF6tube (a maximum of approxi-mately 13.0 g UF6) limits the number and size of the aliquantsthat can be obtained from each tube. See analytical proceduresfor their requirem
16、ents.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.3Other gra
17、des of reagentsmay be used, provided it is first ascertained that the reagent isof sufficiently high purity to permit its use without lesseningthe accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean laboratory-accepteddeminerali
18、zed or deionized water.7.3 Liquid nitrogen.7.4 Water, deionized distilled, cooled to about 4C, approxi-mately 100 mL per sample.7.5 Ethanol or other suitable, volatile organic solvent.8. Hazards8.1 Since UF6materials are radioactive, toxic, and highlyreactive, especially with reducing substances and
19、 moisture,adequate laboratory facilities and fume hoods along with safetechniques must be used in handling samples containing thesematerials. A detailed discussion of all necessary precautions isbeyond the scope of this practice. However, personnel whohandle radioactive materials should be familiar
20、with the safehandling practices of the facility.8.2 Follow all safety procedures for handling uranium andUF6provided by the facility. Review the Material Safety DataSheet (MSDS) for UF6prior to performing the procedure.8.3 Perform dissolutions in a laboratory hood. Hoods shouldbe regularly inspected
21、 for proper air flow.8.4 Gaseous UF6, when released to the atmosphere, reactswith moisture to form HF gas and UO2F2particulate (a whiteamorphous solid that settles on all surfaces). Release of UF6tothe atmosphere is readily visible as a white cloud. Thecorrosive nature of HF and UF6can cause skin bu
22、rns and lungimpairment. Medical evaluation is mandatory for all situationswhere there may have been inhalation or contact with HF orUF6. Water soluble UO2F2, when inhaled or ingested in largequantities, is toxic to the kidneys.8.5 Use gloves designed for use with cryogenic substances,and wear goggle
23、s or a face shield when handling bulkquantities of liquid nitrogen.9. Procedure9.1 Preparation:9.1.1 Check the appearance of the UF6P-10 tube. Reject thetube if it exhibits discoloration of the contents. Wipe theoutside of the tube with a lintless tissue moistened with asuitable, volatile organic so
24、lvent (for example, ethanol) andallow to air-dry. Allow the tube to stand overnight to equili-brate with room air, or place the P-10 tube in a dessicator forat least on hour.9.1.2 Using a 4- or 5- decimal place balance, weigh thesample tube to constant weight. Identify this initial massweight as Wg.
25、9.1.3 To reduce any loss of liquid nitrogen during thedissolution procedure, the Dewar flask and the P-10 tube maybe cooled in a refrigerator prior to use (optional).9.2 Dissolution:9.2.1 Wearing cryogenic gloves and a face shield orgoggles, fill the Dewar with liquid nitrogen and place it in thehoo
26、d and cover with a lid such as aluminum foil duringtransport.9.2.2 Option 1Slip the P-10 tube into a loop of copperwire. Holding on to the end of the wire, lower the tube into theliquid nitrogen without submerging the Monel fittings. Securethe wire by bending it over the top edge of the Dewar flask.
27、Cover the Dewar flask with aluminum foil or other suitablecovering.9.2.3 Option 2Submerge the entire P-10 tube into theliquid nitrogen. Cover the Dewar flask with aluminum foil orother suitable covering.9.2.4 Leave the tube suspended in liquid nitrogen for at leastten minutes. Immediately before rem
28、oving the tube, pourapproximately 50 100 mL ice-cold (approximately 4C)distilled deionized water into a platinum dish.NOTE 3The volume of ice-cold distilled deionized water must besufficient to cover the opening in the P-10 tube.NOTE 4For steps 9.2.5 through 9.2.9, try to minimize elapsed timewhile
29、maximizing care in handling.9.2.5 Wearing cryogenic gloves remove the P-10 tube fromthe liquid nitrogen. Quickly position the tube vertically in thevise, with the Monel fittings on top.9.2.6 Use a wrench to loosen the Monel plug. Remove theplug and place it in a stainless steel beaker or plastic dis
30、h or ona plastic cover.9.2.7 Gently push (the flat end of a TFE-fluorocarbonspatula, may be used) the fluorothene tube upward through thenut until just enough of the tube emerges to securely grasp thefluorothene tube. Hold the gasket gently but firmly in placewith a gloved index finger.9.2.8 Pull th
31、e tube through its Monel nut, and lay it on itsside in a platinum dish containing the ice-cold (approximatley4C) distilled, deionized water. Either a platinum or fluoroth-ene rod and bent-tip forceps, or the rod alone, or the forceps3Reagent Chemicals, American Chemical Society Specifications, Ameri
32、canChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USP
33、C), Rockville,MD.C 13462alone may be used, as necessary, to dislodge the gasket andfacilitate the flow of water into the tube.9.2.9 Remove the nut from the holder and place it in thestainless steel beaker or plastic dish or on the plastic cover withthe plug.9.2.10 With the tips of the bent-tips forc
34、eps partiallyopened, push the gasket up on the wall of the platinum dish. Asthe gasket emerges above the solution, grasp it securely withthe forceps.9.2.11 Carefully rinse the gasket and forceps with distilleddeionized water into the solution and place the gasket in thestainless steel beaker or plas
35、tic dish or on the plastic cover withthe Monel fittings.9.2.12 Place the platinum dish in the hood for at least 24 hto ensure that dissolution is complete. (Dissolution is completewhen yellow solution completely fills the tube.) A plastic covermay be placed on the platinum dish at this time.NOTE 5St
36、eps 9.2.13 and 9.2.14 are optional, but if one is done, bothmust be done.9.2.13 After dissolution appears to be complete, place theplatinum dish (with tube) on a steam bath for1htoreduce thevolume of solution and ensure complete hydrolysis.9.2.14 Remove the platinum dish from the steam bath andallow
37、 to cool to ambient temperature.9.2.15 After dissolution appears to be complete, carefullyremove the empty tube from the solution using either thebent-tip clamping forceps or fluorothene rod, as appropriate,with distilled deionized water into the solution. Do not splash.Place the tube in the stainle
38、ss steel beaker or plastic dish or onthe plastic cover with the Monel fittings and gasket.9.2.16 Option 1Allow the emptied tube to air-dry over-night. Place the parts in a desiccator for at least one hour toremove adsorbed water, then reassemble.9.2.17 Option 2Place the P-10 tube in a vacuum oven at
39、80C and at -29 in. Hg for 2 h. Remove the P-10 tube partsfrom the vacuum oven and allow the tube to come to ambienttemperature (2 h minimu), the reassemble.9.2.18 Weigh the tubeto constant weight using the samebalance as in 9.1.2 . Record all weights. Identify the finalweight as Wt.9.2.19 The soluti
40、on from 9.2.15 may either be dried forgravimetric conversion to U3O8, or transferred to an appropri-ate container for dilution and subsampling for chemical orisotopic analysis.10. Calculations10.1 Buoyancy Corrections:10.1.1 Weight of UF6dissolved (Wc), corrected for airbuoyancy and cover gas, in gr
41、ams.4,5Wc5 20.0058! 1 1.00047! Wg2 Wt! (1)where:Wg= weight of P-10 tube containing UF6, in grams, andWt= weight of empty P-10 tube, in grams.NOTE 6This buoyancy correction applies to the sample tube in Fig. 1.The constants in the equation may differ for different sample tubes.11. Keywords11.1 dissol
42、ution; P-10 tube; uranium hexafluoride; uraniumhexafluoride dissolutionASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of
43、any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are
44、 invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not rece
45、ived a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) o
46、f this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).4Hedge, W. D., “Empirical Cover Gas Correction, Sample Freezing Time, andAir Buoyancy Adjustment for the Analy
47、sis of Uranium in Uranium Hexafluoride,”Report K-2051, Oak Ridge Gaseous Diffusion Plant, Martin Marietta EnergySystems, Inc., Oak Ridge, TN, July 31, 1985.5Hedge, W. D., “Composite Net UF6Weight Data,” Martin Marietta EnergySystems, Inc., Oak Ridge Gaseous Diffusion Plant, ANALIS correspondence to R.E. Simmons, Paducah Gaseous Diffusion Plant; H. H. Sullivan, Oak Ridge GaseousDiffusion Plant; and O. A. Vita, Goodyear Atomic Corporation, May 28, 1986.C 13463
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