1、Designation: C1346 08 (Reapproved 2014)Standard 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
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 practice covers the dissolution of UF6from a P-10tube to provide solutions for analysis.1.2 The values stated in SI units are to
3、be regarded asstandard. 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 and health practices and
4、determine the applica-bility of regulatory limitations prior to use. For specificsafeguard and safety precaution statements, see Section 8.2. Referenced Documents2.1 ASTM Standards:3C761 Test Methods for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and RadiochemicalAnalysis ofUranium Hexaf
5、luorideC787 Specification for Uranium Hexafluoride for Enrich-mentC996 Specification for Uranium Hexafluoride Enriched toLess Than 5 %235UD1193 Specification for Reagent Water3. Summary of Practice3.1 UF6samples intended for analysis are packaged in P-10tubes to prevent sublimation and reaction with
6、 moisture in theair. The P-10 tube assembly (Fig. 1) consists of a Polychloro-trifluoroethylene (PCTFE) tube containing the UF6, a PCTFEgasket to cover the tubes opening, and a nut and plug (Monelor SS) to seal the gasket to the tube.3.2 The UF6tube is weighed, cooled in liquid nitrogen, andquickly
7、opened and immersed in water for dissolution. Thepieces of the tubes assembly are removed from the resultingsolution, rinsed, dried, reassembled, and weighed. The solutionis dried for gravimetric conversion to U3O8, or diluted to anappropriate concentration for dispensing into aliquots forsubsequent
8、 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 compositionand metallic impurities in Specification C787 and C996. Thispractice results in t
9、he complete dissolution of the sample foruranium and impurities analysis, and determination of isotopicdistribution by mass spectrometry as described in, for example,Test Methods C761.5. Apparatus5.1 Steam bath, in a hood, if optional step 9.2.13 is used.5.2 Vacuum oven, if option 2 of 9.2.14 is use
10、d. The ovenshould be adjustable to 80C at an absolute pressure of 3 103Pa.5.3 Dewar flask, wide-mouth.5.4 Vise, small lab-bench model or similar 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 PCTFE tube.NOT
11、E 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.5.7 TFE-fluorocarbon-coated spatula, 0.5- to 1-cm wide atits flat end, optional.5.8 Platinum or PCTFE rod, optional.5.9 Platinum dish
12、es or plastic beakers with compatible HFresistance (typically PolyEthylene; PE), large enough to con-tain a completely submerged P-10 tube.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.Cur
13、rent edition approved Jan. 1, 2014. Published February 2014. Originallyapproved in 1996. Last previous edition approved in 2008 as C1346 08. DOI:10.1520/C1346-08R14.2Polychlorotrifluoroethylene P-10 tubes are widely accepted by the industry forsubsample collection and subsequent UF6quality analyses
14、or dispatch to thecustomer. The procedure for subsample collection 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 r
15、eferenced 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 Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, W
16、est Conshohocken, PA 19428-2959. United States15.10 Copper wires, optional. The wires should be flexibleand looped at one end to loosely fit around the PCTFE tubewithout allowing the flare nut to pass through.5.11 Desiccator, optional.5.12 Balance, 100-g capacity, readable to at least 0.1 mg,prefera
17、bly 0.01 mg.NOTE 2Use of a balance with lower sensitivity will negatively impacton sampling error.6. Interferences6.1 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.6.2 The capacity of
18、the UF6tube (a maximum of approxi-mately 13.0 g UF6) limits the number and size of the aliquotsthat can be obtained from each tube. See analytical proceduresfor their requirements.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is in
19、tended thatall reagents conform to the specifications of the Committee onAnalytical Reagents 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
20、 without lesseningthe accuracy of the determination.7.2 Liquid nitrogen.7.3 Deionized distilled water in accordance with Specifica-tion D1193, approximately 50100 cm3per sample.7.4 Ethanol or other suitable, volatile organic solvent.8. Hazards8.1 Since UF6materials are radioactive, toxic, and highly
21、reactive, especially with reducing substances and 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 wh
22、ohandle radioactive materials should be familiar 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 la
23、boratory hood. Hoods shouldbe regularly inspected 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. T
24、hecorrosive nature of HF and UF6can cause skin burns 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
25、for use with cryogenic substances,and wear goggles or a face shield when handling bulkquantities of liquid nitrogen.9. Procedure9.1 Preparation:9.1.1 Wipe the outside of the tube with a lintless tissuemoistened with a suitable, volatile organic solvent (forexample, ethanol) and allow to air-dry. All
26、ow the tube to standovernight to equilibrate with room air, or place the P-10 tube ina dessicator for at least one hour.NOTE 3P-10 tubes can occasionally exhibit some discoloration due totrace amounts of impurities. These tubes can be used for further analysesprovided that these subsequent analyses
27、confirm compliance with theimpurity limits as stated in Specification C787 and C996. Discolorationcould necessitate further investigation into the causes.9.1.2 Using a 4- or 5- decimal place balance, weigh thesample tube to constant weight. Identify this initial massweight as Wg.9.1.3 To reduce any
28、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, optionally coveredwith a lid such as alum
29、inum foil during transport, and place itin the hood.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 fittings. Secure the wireby bending it over the top edge of the Dewar flask. Cover theDewar
30、 flask with aluminum foil or other suitable covering.9.2.3 Option 2Submerge the entire P-10 tube into theliquid nitrogen. The Dewar flask may be covered with alumi-num foil or other suitable covering.9.2.4 Leave the tube suspended in liquid nitrogen for at leastten minutes. Immediately before removi
31、ng the tube, pour4Reagent 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., and the United
32、States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 1 Example of a P-10 Sample TubeC1346 08 (2014)2approximately 50100 cm3distilled deionized water into aplatinum dish or PE beaker.NOTE 4The volume of distilled deionized water must be sufficient t
33、ocover the opening in the P-10 tube.NOTE 5For steps 9.2.5 through 9.2.9, try to minimize elapsed timewhile 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 fittings on top.9.2.6 Use a wr
34、ench to loosen the plug. Remove the plug andplace it in a stainless steel beaker or plastic dish or on a plasticcover.9.2.7 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.
35、 Hold the gasket gently but firmly in place with agloved index finger.9.2.8 Pull the tube through its nut, and lay it on its side in aplatinum 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
36、 used, as necessary,to dislodge the gasket and facilitate the flow of water into thetube.9.2.9 Remove the nut from the vise and place it in thestainless steel beaker or plastic dish or on the plastic cover withthe plug.9.2.10 With the tips of the bent-tips forceps partiallyopened, push the gasket up
37、 on the wall of the platinum dish orPE beaker. As the gasket emerges above the solution, grasp itsecurely with the 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 plastic dish or on the plastic
38、 cover withthe 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.)Aplastic covermay be placed on the platinum dish or PE beaker at this time.NOTE 6In order to reduce the
39、volume of the of the solution, theplatinum dish (with P-10 tube) can 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 9.2.13.9.2.13 After dis
40、solution appears to be complete, carefullyremove the empty tube from 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 o
41、n the plastic cover with the fittings and gasket.9.2.14 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.9.2.15 Option 2Place the P-10 tube parts in a vacuumoven at 80C and at an absolute pressure of3
42、103Pa for 2 h.Remove the P-10 tube parts from the vacuum oven and allowthe tube to come to ambient temperature (2 h minimum), thenreassemble.9.2.16 Weigh the tube to constant weight using the samebalance as in 9.1.2. Record all weights. Identify the finalweight as Wt.9.2.17 The solution from 9.2.13
43、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 grams.5,6Wc5 20.0
44、058!11.00047!Wg2 Wt! (1)where:Wg= weight of P-10 tube containing UF6, in grams, andWt= weight of empty P-10 tube, in grams.NOTE 7This buoyancy correction applies to the sample tube in Fig. 1.The constants in the equation may differ for different sample tubes.11. Keywords11.1 dissolution; P-10 tube;
45、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 any such patent ri
46、ghts, 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 invited either fo
47、r 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 received a fair hearin
48、g 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) of this standard ma
49、y 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).5Hedge, 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.
