1、Designation: C1346 19Standard Practice forDissolution of UF6from P-10 Tubes1,2This standard is issued under the fixed designation C1346; 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 () 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 The values stated in SI units are to be regarded asstan
3、dard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and de
4、ter-mine the applicability of regulatory limitations prior to use.For specific safeguard and safety precaution statements, seeSection 9.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principle
5、s for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3C761 Test Methods for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and RadiochemicalAnal
6、ysis ofUranium HexafluorideC787 Specification for Uranium Hexafluoride for Enrich-mentC859 Terminology Relating to Nuclear MaterialsC996 Specification for Uranium Hexafluoride Enriched toLess Than 5 %235UD1193 Specification for Reagent Water3. Terminology3.1 Definitions:3.1.1 For definitions of term
7、s relating to the nuclear fuelcycle, refer to Terminology C859.4. Summary of Practice4.1 UF6samples intended for analysis are packaged in P-10tubes to prevent sublimation and reaction with moisture in theair. The P-10 tube assembly (Fig. 1) consists of a Polychloro-trifluoroethylene (PCTFE) tube con
8、taining the UF6, a PCTFEgasket to cover the tubes opening, and a nut and plug (Monelor SS) to seal the gasket to the tube.4.2 The UF6tube is weighed, cooled in liquid nitrogen, andquickly opened and immersed in water for dissolution. Thepieces of the tubes assembly are removed from the resultingsolu
9、tion, rinsed, dried, reassembled, and weighed. The solutionis dried for gravimetric conversion to U3O8, or diluted to anappropriate concentration for dispensing into aliquots forsubsequent analysis.5. Significance and Use5.1 Uranium hexafluoride is a basic material used to preparenuclear reactor fue
10、l. To be suitable for this purpose the materialmust meet criteria for uranium content, isotopic compositionand metallic impurities in Specification C787 and C996. Thispractice results in the complete dissolution of the sample foruranium and impurities analysis, and determination of isotopicdistribut
11、ion by mass spectrometry as described in, for example,Test Methods C761.6. Apparatus6.1 Steam bath, in a hood, if optional step 10.2.13 is used.6.2 Vacuum oven, if option 2 of 10.2.14 is used. The ovenshould be adjustable to 80C at an absolute pressure of 3 103Pa.6.3 Dewar flask, wide-mouth.6.4 Vise
12、, small lab-bench model or similar type of holder.6.5 Wrench,1516 in.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 Feb. 1, 2019. Published February 2019. Originall
13、yapproved in 1996. Last previous edition approved in 2014 as C1346 08 (2014).DOI: 10.1520/C1346-19.2Polychlorotrifluoroethylene P-10 tubes are widely accepted by the industry forsubsample collection and subsequent UF6quality analyses or dispatch to thecustomer. The procedure for subsample collection
14、 and dissolution can also be usedfor other types of subsample tubes, for example, P-20, P-80 or P-100, in that casethe amount of water has to be adjusted to ensure complete hydrolisation of UF6andavoid excessive heat evolution.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orc
15、ontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international st
16、andard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.16.6
17、 Plastic clamping forceps, 12 to 13 cm long, with aclaw-like bent tip, to securely hold the cylindrical PCTFE tube.NOTE 1These forceps are not commercially available. Bend the endsof a straight-tip forceps by heating over a moderate flame, shaping, andmaintaining the shape until cool.6.7 TFE-fluoroc
18、arbon-coated spatula, 0.5- to 1-cm wide atits flat end, optional.6.8 Platinum or PCTFE rod, optional.6.9 Platinum dishes or plastic beakers with compatible HFresistance (typically PolyEthylene; PE), large enough to con-tain a completely submerged P-10 tube.6.10 Copper wires, optional. The wires shou
19、ld be flexibleand looped at one end to loosely fit around the PCTFE tubewithout allowing the flare nut to pass through.6.11 Desiccator, optional.6.12 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 samplin
20、g error.7. Interferences7.1 The weight of the PCTFE tube is affected by atmo-spheric humidity. Keep the P-10 tube assembly in a desiccatorbetween weighings until constant weight is attained.7.2 The capacity of the UF6tube (a maximum of approxi-mately 13.0 g UF6) limits the number and size of the ali
21、quotsthat can be obtained from each tube. See analytical proceduresfor their requirements.8. Reagents8.1 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 Reagen
22、ts of the American Chemical Society wheresuch specifications are available.4Other grades 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.8.2 Liquid nitrogen.8.3 Deionized dist
23、illed water in accordance with Specifica-tion D1193, approximately 50 to 100 cm3per sample.8.4 Ethanol or other suitable, volatile organic solvent.9. Hazards9.1 Uranium hexafluoride (UF6) is radioactive, toxic, andhighly reactive especially with reducing substances and mois-ture. Appropriate laborat
24、ory facilities, materials ofconstruction, and techniques shall be utilized when handlingUF6.9.2 Follow all safety procedures for handling uranium andUF6provided by the facility. Review the Safety Data Sheet(SDS) for UF6prior to performing the procedure.9.3 Perform dissolutions in a laboratory hood.
25、Hoods shouldbe regularly inspected for proper air flow.9.4 When released to the atmosphere, gaseous UF6reactswith moisture to produce HF gas and toxic UO2F2particulates.Use sufficient ventilation or respiratory protection to avoidbreathing fumes. Use appropriate personal protective equip-ment such a
26、s gloves, eye, and face protection.9.5 Hydrofluoric acid is a highly corrosive acid that canseverely burn skin, eyes, and mucous membranes. Hydroflu-oric acid differs from other acids because the fluoride ionreadily penetrates the skin, causing destruction of deep tissuelayers. Unlike other acids th
27、at are rapidly neutralized, hydro-fluoric acid reactions with tissue may continue for days if leftuntreated. Familiarization and compliance with the Safety DataSheet (SDS) is essential.9.6 Use gloves designed for use with cryogenic substances,and wear goggles or a face shield when handling bulkquant
28、ities of liquid nitrogen.10. Procedure10.1 Preparation:10.1.1 Wipe the outside of the tube with a lintless tissuemoistened with a suitable, volatile organic solvent (forexample, ethanol) and allow to air-dry. Allow the tube to standovernight to equilibrate with room air, or place the P-10 tube ina d
29、essicator for at least one hour.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical 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.,
30、and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 1 Example of a P-10 Sample TubeC1346 192NOTE 3P-10 tubes can occasionally exhibit some discoloration due totrace amounts of impurities. These tubes can be used for further analyses
31、provided that these subsequent analyses confirm compliance with theimpurity limits as stated in Specification C787 and C996. Discolorationcould necessitate further investigation into the causes.10.1.2 Using a 4- or 5- decimal place balance, weigh thesample tube to constant weight. Identify this init
32、ial massweight as Wg.10.1.3 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).10.2 Dissolution:10.2.1 Wearing cryogenic gloves and a face shield orgoggles, fill the Dewar with liquid nitroge
33、n, optionally coveredwith a lid such as aluminum foil during transport, and place itin the hood.10.2.2 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 fittings. Secure the wireby bending it over th
34、e top edge of the Dewar flask. Cover theDewar flask with aluminum foil or other suitable covering.10.2.3 Option 2Submerge the entire P-10 tube into theliquid nitrogen. The Dewar flask may be covered with alumi-num foil or other suitable covering.10.2.4 Leave the tube suspended in liquid nitrogen for
35、 atleast ten minutes. Immediately before removing the tube, pourapproximately 50 to 100 cm3distilled deionized water into aplatinum dish or PE beaker.NOTE 4The volume of distilled deionized water must be sufficient tocover the opening in the P-10 tube.NOTE 5For steps 10.2.5 through 10.2.9, try to mi
36、nimize elapsed timewhile maximizing care in handling.10.2.5 Wearing cryogenic gloves remove the P-10 tube fromthe liquid nitrogen. Quickly position the tube vertically in thevise, with the fittings on top.10.2.6 Use a wrench to loosen the plug. Remove the plugand place it in a stainless steel beaker
37、 or plastic dish or on aplastic cover.10.2.7 Gently push (the flat end of a TFE-fluorocarbonspatula, may be used) the PCTFE tube upward through the nutuntil just enough of the tube emerges to securely grasp thePCTFE tube. Hold the gasket gently but firmly in place with agloved index finger.10.2.8 Pu
38、ll the tube through its nut, and lay it on its side ina platinum dish or PE beaker containing the distilled, deionizedwater. Either a platinum or PCTFE rod and bent-tip forceps, orthe rod alone, or the forceps alone may be used, as necessary,to dislodge the gasket and facilitate the flow of water in
39、to thetube.10.2.9 Remove the nut from the vise and place it in thestainless steel beaker or plastic dish or on the plastic cover withthe plug.10.2.10 With the tips of the bent-tips forceps partiallyopened, push the gasket up on the wall of the platinum dish orPE beaker. As the gasket emerges above t
40、he solution, grasp itsecurely with the forceps.10.2.11 Carefully rinse the gasket and forceps with distilleddeionized water into the solution and place the gasket in thestainless steel beaker or plastic dish or on the plastic cover withthe fittings.10.2.12 Place the platinum dish in the hood for at
41、least 2 to4 h to ensure that dissolution is complete. (Dissolution iscomplete when yellow solution completely fills the tube.) Aplastic cover may be placed on the platinum dish or PE beakerat this time.NOTE 6In order to reduce the volume of the of the solution, theplatinum dish (with P-10 tube) can
42、be placed in a heating apparatus forapprox. 1 h after the dissolution appears to be complete. Remove theplatinum dish from the heating apparatus and allow to cool to ambienttemperature before proceeding with 10.2.13.10.2.13 After dissolution appears to be complete, carefullyremove the empty tube fro
43、m the solution using either thebent-tip clamping forceps or PCTFE rod, as appropriate, andrinse the tube with distilled deionized water into the solution.Do not splash. Place the tube in the stainless steel beaker orplastic dish or on the plastic cover with the fittings and gasket.10.2.14 Option 1Al
44、low the emptied tube to air-dry over-night. Place the parts in a desiccator for at least one hour toremove adsorbed water, then reassemble.10.2.15 Option 2Place the P-10 tube parts in a vacuumoven at 80C and at an absolute pressure of3103Pa for 2 h.Remove the P-10 tube parts from the vacuum oven and
45、 allowthe tube to come to ambient temperature (2 h minimum), thenreassemble.10.2.16 Weigh the tube to constant weight using the samebalance as in 10.1.2. Record all weights. Identify the finalweight as Wt.10.2.17 The solution from 10.2.13 may either be dried forgravimetric conversion to U3O8, or tra
46、nsferred to an appropri-ate container for dilution and subsampling for chemical orisotopic analysis.11. Calculations11.1 Buoyancy Corrections:11.1.1 Weight of UF6dissolved (Wc), corrected for airbuoyancy and cover gas, in grams.5, 6Wc5 20.0058!11.00047!Wg2 Wt! (1)where:Wg= weight of P-10 tube contai
47、ning UF6, in grams, andWt= weight of empty P-10 tube, in grams.NOTE 7This buoyancy correction applies to the sample tube in Fig. 1.The constants in the equation may differ for different sample tubes.12. Keywords12.1 dissolution; P-10 tube; uranium hexafluoride; uraniumhexafluoride dissolution5Hedge,
48、 W. D., “Empirical Cover Gas Correction, Sample Freezing Time, andAir Buoyancy Adjustment for the Analysis of Uranium in Uranium Hexafluoride,”Report K-2051, Oak Ridge Gaseous Diffusion Plant, Martin Marietta EnergySystems, Inc., Oak Ridge, TN, July 31, 1985.6Hedge, W. D., “Composite Net UF6Weight D
49、ata,” 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.C1346 193ASTM 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 any such patent rights, and the riskof infringement of such rights,
