1、Designation: C1689 08a (Reapproved 2014)Standard Practice forSubsampling of Uranium Hexafluoride1This standard is issued under the fixed designation C1689; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、A 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 is applicable to subsampling uraniumhexafluoride (UF6), using heat liquefaction techniques, frombulk containers, obtain
3、ed in conformance with C1052, intosmaller sample containers, which are required for laboratoryanalyses.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 It is assumed that the liquid UF6being sampled com-prises a single qu
4、ality and quantity of material. This practicedoes not address any special additional arrangement that mightbe required for taking proportional or composite samples.1.4 The number of samples to be taken, their nominalsample weight, and their disposition shall be agreed uponbetween the parties.1.5 The
5、 scope of this practice does not include provisionsfor preventing criticality incidents.1.6 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
6、 and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C787 Specification for Uranium Hexafluoride for Enrich-mentC859 Terminology Relating to Nuclear MaterialsC996 Specification for Uranium Hexafluoride Enriched toLess Than 5 %235UC761 Te
7、st Methods for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and RadiochemicalAnalysis ofUranium HexafluorideC1052 Practice for Bulk Sampling of Liquid UraniumHexafluoride2.2 Other Documents:ANSI N14.1 Uranium Hexafluoride: Packaging for Trans-port3ISO/DIS 7195 Packaging of Uranium Hexafluo
8、ride (UF6)for Transport4USEC-651 The UF6Manual: Good Handling Practices forUranium Hexafluoride, latest revision53. Terminology3.1 Terms shall be defined in accordance with TerminologyC859 except for the following:3.1.1 sample bottlethe vessel (typically a 1S or 2S bottle)into which the sample of UF
9、6is withdrawn from the containerfor transfer to the laboratory, analysis or dispatch to thecustomer.3.1.2 subsample tubethe small vessel (for example, a P10tube6) into which a subsample of UF6is withdrawn from thesample bottle for analysis of UF6quality or dispatch to thecustomer.3.1.3 subsample rig
10、the equipment to perform the transferof liquid UF6from the sample bottle into the subsample tube,typically a vacuum manifold equipped with heating and aliquid nitrogen trap.4. Summary of Practice4.1 Two methods of withdrawing a subsample of UF6aredescribed which differ based on safety requirements n
11、amely: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. 1, 2014. Published February 2014. Originallyapproved in 2008. Last previous edition approved in 2008 as C1
12、689 08a. DOI:10.1520/C1689-08aR14.2For 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 Document Summary page onthe ASTM website.3Available from American Na
13、tional Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.5Available from United States Enrichme
14、nt Corp., 6903 Rockledge Dr., Bethesda,MD 20817, http:/.6Polychlorotrifluoroethylene P10 tubes are widely accepted by the industry forsubsample collection and subsequent UF6quality analyses or dispatch to thecustomer. Other types of subsample tubes, for example P-20, P-80 or P100 , can beused for in
15、ternal subsample collection and processing. Dispatch of these subsampletubes may be agreed upon by buyer and seller and subject to (local) transportregulations.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1(1) homogenizing of liquef
16、ied UF6by agitation before liquidtransfer and (2) homogenizing of liquefied UF6by convectionbefore liquid transfer. The first method involves homogeniza-tion of liquified UF6in a sample bottle by vigorous shaking.Subsequently the sample bottle is inverted and connected to thetop of a heated vacuum-m
17、anifold system, and the subsampletube is attached to the appropriate port of the system. Thesystem is evacuated and the liquid UF6allowed to flow bygravity into the subsample tube. In the second method thesample bottle containing solid UF6is connected to the top of amanifold system, and a subsample
18、tube is attached to theappropriate port of the system.The whole system is enclosed insecondary containment that can be heated (hot-box). Afterevacuation the complete system is heated for specific period(typically 1.5 hr) to allow for complete homogenization ofthe liquid UF6by convection. Subsequentl
19、y the liquid UF6isallowed to flow by gravity either directly or via graduatedvolume into the subsample tube.4.2 For both methods of sampling, the presence of residuesmay have significant implications for the quality of UF6. Forsafety and quality reasons, sample bottles and subsample tubesshall be cl
20、ean, dry, and empty before filling.4.3 Various types of sample bottles and tubes are in use andare described in detail in the applicable national and interna-tional standards, for example, ANSI N14.1 and ISO/DIS 7195.For a given type of sample bottle, the detailed configuration,for example valve ori
21、entation, terminal fittings and the like,may vary. Hence the type and configuration of bottles used forthe withdrawal of samples shall be agreed upon between theparties.5. Significance and Use5.1 Uranium hexafluoride is normally produced and handledin large (typically 1- to 14-ton) quantities and mu
22、st, thereforebe characterized by reference to representative samples. Thesamples are used to determine compliance with the applicablecommercial Specifications C996 and C787 by means of theappropriate test method (for example, Test Method C761 andreferences therein). The quantities involved, physical
23、properties, chemical reactivity, and hazardous nature of UF6are such that for representative sampling, specially designatedequipment must be used and operated in accordance with themost carefully controlled and stringent procedures. This prac-tice indicates appropriate principles, equipment and proc
24、edurescurrently in use for subsampling of liquid UF6. It is used byUF6converters, enrichers and fuel fabricators to review theeffectiveness of existing procedures or to design equipment andprocedures for future use. Other subsampling procedures suchas UF6vapor sampling are not directly representativ
25、e of thechemical quality of liquid UF6.5.2 It is emphasized that this test guide is not meant toaddress conventional or nuclear criticality safety issues.6. Apparatus6.1 Hot Water Bath.6.2 Subsample RigFor Procedure 1 see Fig. 1 and Proce-dure 2 see Fig. 2. Materials of construction in direct contac
26、twith liquid UF6are made from nickel, high nickel alloys, ormaterials having comparable resistance to UF6corrosion.6.3 Gaseous Isotopic Abundance Sample Tube (Fig. 3).NOTE 1All lines are38 in. (9.5 mm) Monel tubing.NOTE 2All valves are Monel diaphragm type valves.NOTE 3The valves and lines are wrapp
27、ed with heating tape to maintain a system temperature of about 80C.NOTE 4Valve 2 is a 3-way valve modified to make it a 4-way valve. When the valve is closed, the polychlorotrifluoroethylene tube is isolated fromthe system, but the lines from valve 1 to valve 3 and to the bulk container are open.FIG
28、. 1 Subsample Rig Used for Procedure 1C1689 08a (2014)26.4 Polychlorotrifluoroethylene Subsample Tube and Clos-ing Disc (Fig. 4)The tube must be of uniform density, freefrom cracks or occlusions and able to withstand temperaturesfrom 195C to +150C. Materials of construction in directcontact with liq
29、uid UF6are made frompolychlorotrifluoroethylene, PTFE/TFE (gaskets), or materialshaving comparable resistance to UF6corrosion.6.5 Flare Nut and PlugFlare nuts and plugs for subsampletube closure, storage and transport can be constructed fromMonel, nickel, high nickel alloys or 316 SS.6.6 Polychlorot
30、rifluoroethylene Knockout Cylinder (Fig. 5),closed with a Cajon M-16 VCR-1 female nut and an M-16VCR-4 male nut or equivalent.NOTE 1Brand names mentioned in this practice are intended to betypical, not limiting.Another brand with comparable characteristics couldperform equally well.6.7 Nickel Filter
31、 Disc, porous, 2m, free of chromium (Fig.6).NOTE 2The filterdisc should weigh approximately 1 g. It should bemade of nickel powder produced from carbonyl nickel and formed by theno pressure sintering method in graphite or ceramic molds.6.8 Gas Sample Cylinder.6.9 Heat SourcesHeat gun (or an equivale
32、nt) and heatlamps.6.10 Dewar Flask, for liquid nitrogen, stainless steel.7. Hazards7.1 Uranium hexafluoride (UF6) is radioactive, toxic andhighly reactive especially in the presence of reducing sub-stances and moisture. Safe techniques must be utilized whenhandling UF6. Suitable handling procedures
33、are described inUSEC-651.7.2 Follow all safety procedures for handling UF6as pro-vided by your facility.7.3 Review Material Safety Data Sheets for UF6and allchemicals associated with this method prior to performance.7.4 Perform subsampling operations in a fume hood that hasbeen verified operable and
34、 has undergone regular inspectionsto ensure proper airflow.7.5 When released to atmosphere, gaseous UF6reacts withmoisture to produce HF gas and UO2F2particulates (a whiteamorphous solid) and becomes readily visible as a white cloud.The corrosive nature of HF and UF6can result in skin burnsNOTE 1All
35、 lines in direct contact with liquid UF6are38 in. (9.5 mm) Monel tubing.NOTE 2All other lines are in. (9.5 mm) 316 SS tubing.NOTE 3Valves 13 are Monel below sealed valves that can be operated from outside the hotbox.NOTE 4Valves 48 are 316 SS below sealed valves.NOTE 5Flange connections are equipped
36、 with helicoflex (high pressure) gaskets.FIG. 2 Subsample Rig Used for Procedure 2C1689 08a (2014)3and lung impairment. Medical evaluation is mandatory afterFIG. 3 Isotopic Abundance Sample Tube.FIG. 4 Example of a Polychlorotrifluoroethylene Subsample TubeC1689 08a (2014)4contact with HF or UF6. Wh
37、en water-soluble UO2F2is inhaledor ingested in large quantities it can be toxic to the kidneys.FIG. 5 Example of a Polychlorotrifluoroethylene Knock-out TubeFIG. 6 Filter Disc Unit for Determination of Soluble and Insoluble ChromiumC1689 08a (2014)58. Principles8.1 The essential purpose of the sampl
38、e is to be represen-tative of the bulk material for the purpose of determiningcompliance with the applicable material specification. Toensure that the sample is representative for this purpose, certainprinciples, as described below, must be observed.8.2 Special attention must be given to ensuring th
39、at the bulkmaterial, from which the sample is withdrawn, is homoge-neous. In practice, the low viscosity, and hence easy mobilityof liquid UF6facilitates the process of homogenization by theaction of convection currents within the bulk upon heating. Itis necessary to determine and establish for each
40、 set ofsubsampling equipment the physical conditions, normally acombination of the minimum time and temperature for whichliquefied uranium hexafluoride is held, which guaranty homo-geneity of the bulk UF6.8.3 Uranium hexafluoride is very reactive and corrosive. Itreacts readily with water, atmospher
41、ic moisture and manyorganic materials. For reasons of safety and to avoidcontamination, precautions must be taken to avoid contact withsuch materials. The subsampling equipment and subsampletube are therefore fabricated to appropriate high standards ofvacuum integrity, and components in direct conta
42、ct with liquidUF6are made from nickel, high nickel alloys, or materialshaving comparable resistance to UF6corrosion. The formationof an inert fluoride layer is often an important feature of UF6corrosion resistance, and hence internal surfaces are generallyconditioned with a suitable fluorinating age
43、nt, sometimes UF6itself.8.4 Cross-contamination may occur between subsequentsamples taken using the same equipment, and appropriateprecautions must be taken to prevent this. It is thereforerecommended that, before taking definitive samples, the equip-ment is flushed through with an aliquot of the ma
44、terial to besampled. This is normally accomplished by taking an initialvolume which is then rejected and not used for definitiveanalysis. Alternative procedures to prevent cross-contamination are possible and should be validated individu-ally.8.5 If sample bottles are taken for an analytical need su
45、ch asliquid UF6subsampling for P10 tubes or liquid UF6transfer forFTIR quantification, it is recommended, in order to minimizethe gas phase contribution to the sample bottle, to fill the bottlewith more than 10 % of its total volume.9. Subsampling Schemes for UF6Specification Analyses9.1 The number
46、and type of subsamples taken from asample bottle (typically 1S or 2S bottle) depends both on thesampling requirements (natural UF6, enriched UF6and particu-lar agreements between buyer and seller) and the availableequipment. Below are some typical examples of analyses thatcan be performed and their
47、appropriate subsample tubes.9.2 Uranium isotopic abundance analyses can be performedusing a isotopic abundance sample tube (Fig. 3, uraniumcontent appr. 4 g), a polychlorotrifluoroethylene tube (P10, Fig.4, UF6 content7g)oralternatively measured directly in thegas phase using the 1S or 2S sample bot
48、tle.9.3 For uranium purity determination a polychlorotrifluoro-ethylene tube (P10, Fig. 4) containing7gofUF6can beused.9.4 Determination of (metallic) impurities, for example B,Si, Tc, Cl, Br, etc., can be performed using a polychlorotrif-luoroethylene tube (P-10, Fig. 4,UF6content7g).9.5 Soluble an
49、d insoluble chromium analyses can be per-formed using a nickel filter disc (Fig. 6) and a polychlorotrif-luoroethylene tube (UF6content 15-20 g).9.6 Subsampling for hydro-, chloro-, and halohydrocarbonanalysis can be performed using a gas sample cylinder 9.99103Pa. Alternatively the analysis can be performed directlyon the 1S or 2S sample bottle.9.7 In order to achieve the typically required detectionlimits for the determination impurities in reprocessed UF6(Pu,Np,232U, -activity of fission products), larger amounts of UF6are req
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