1、Designation: C 1052 01 (Reapproved 2007)Standard Practice forBulk Sampling of Liquid Uranium Hexafluoride1This standard is issued under the fixed designation C 1052; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、revision. A number in parentheses 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 methods for withdrawing represen-tative samples of liquid uranium hexafluoride (UF6) from bulkquantit
3、ies of the material. Such samples are used for determin-ing compliance with the applicable commercial specification,for example Specification C 787 and Specification C 996.1.2 It is assumed that the bulk liquid UF6being sampledcomprises a single quality and quantity of material. Thispractice does no
4、t address any special additional arrangementsthat might be required for taking proportional or compositesamples, or when the sampled bulk material is being added toUF6residues already in a container (“heels recycle”).1.3 The number of samples to be taken, their nominalsample weight, and their dispos
5、ition shall be agreed uponbetween the parties.1.4 The scope of this practice does not include provisionsfor preventing criticality incidents.1.5 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
6、to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 787 Specification for Uranium Hexafluoride for Enrich-mentC 996 Specification for Uranium Hexafluoride Enriched toLess Than 5 %23
7、5U2.2 Other Documents:USEC-651 Uranium Hexafluoride: A Manual of Good Han-dling Practices3ANSI N14.1 Uranium Hexafluoride: Packaging for Trans-port4ISO/DIS 7195 Packaging of Uranium Hexafluoride (UF6)for Transport43. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 containerthe bu
8、lk vessel either holding or receivingby transfer, the UF6to be sampled; it may consist of, forexample, a fixed vessel in a UF6handling plant or a cylinder tobe used for the transport of UF6.3.1.2 sample bottlethe small vessel into which the sampleof UF6is withdrawn for transfer to the laboratory for
9、 charac-terization.4. Summary of Practice4.1 Two methods of withdrawing a sample are described,namely: (1) direct withdrawal from a filled container and (2)withdrawal from the inlet-line during the filling of a containerby liquid transfer. The first method involves tilting or turningthe container in
10、 such a way that its valve is below the surfaceof the liquefied UF6, and dependent on the equipment, thisrequires that the container holds more than a specified mini-mum quantity of UF6. Liquid UF6is withdrawn into agraduated volume and then transferred to the respective samplebottle(s). In the seco
11、nd method, a small proportion of the UF6flowing from one container to another is withdrawn into agraduated volume and then transferred to the respective samplebottle(s).4.2 For both methods of sampling, the presence of residuesmay have significant implications for the quality of the UF6.For safety a
12、nd quality reasons, containers and bottles shall beclean, dry, and empty before filling.4.3 Various types of sample bottles are in use and aredescribed in detail in the applicable national and internationalstandards, for example, ANSI N14.1 and ISO/DIS 7195. For agiven type of sample bottle, the det
13、ailed configuration, forexample, valve orientation, terminal fittings, and the like, may1This practice is under the jurisdiction of ASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.02 on Fuel andFertile Material Specifications.Current edition approved June
14、 1, 2007. Published July 2007. Originally approvedin 1985. Last previous edition approved in 2001 as C 1052 01.2For 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 s
15、tandards Document Summary page onthe ASTM website.3Available from United States Enrichment Corp., 6903 Rockledge Dr., Bethesda,MD 20817.4Available from American National Standards Institute, 11 W. 42nd St., 13thFloor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C7
16、00, West Conshohocken, PA 19428-2959, United States.vary. Hence, the type and configuration of bottles to be 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) qua
17、ntities and must, therefore,be characterized by reference to representative samples. Thequantities involved, physical properties, chemical reactivity,and hazardous nature of UF6are such that for representativesampling, specially designed equipment must be used andoperated in accordance with the most
18、 carefully controlled andstringent procedures. This practice indicates appropriate prin-ciples, equipment, and procedures currently in use for bulksampling of liquid UF6. It is used by UF6converters, enrichers,and fuel fabricators to review the effectiveness of existingprocedures or as a guide to th
19、e design of equipment andprocedures for future use. Other sampling procedures such asUF6vapor sampling are not directly representative of thequality of liquid UF6.5.2 It is emphasized that this practice is not meant to addressconventional or nuclear criticality safety issues.6. Hazards6.1 Because of
20、 its chemical, radiochemical, and toxic prop-erties, UF6is a hazardous material. Suitable handling proce-dures are described in USEC-651.7. Principles7.1 The essential purpose of the sample is to be represen-tative of the bulk material for the purpose of determiningcompliance with the applicable mat
21、erial specification. Toensure that the sample is representative for this purpose, certainprinciples, as described below, must be observed.7.2 Special attention must be given to ensuring that the bulkmaterial from which the sample is withdrawn is homogeneous,particularly in those circumstances when i
22、t has been preparedby the blending together of materials having different compo-sitions. In practice, the low viscosity, and hence easy mobility,of liquid UF6facilitates the process of homogenization by theaction of convection currents within the bulk upon heating. Itis necessary to determine and es
23、tablish for each set of samplingequipment the physical conditions, normally a combination ofthe minimum time and temperature for which liquefied ura-nium hexafluoride is held, which guarantee homogeneity of thebulk UF6.7.3 Uranium hexafluoride is very reactive and corrosive. Itreacts readily with wa
24、ter, atmospheric moisture, certain metals,and many organic materials. For reasons of safety and to avoidcontamination, precautions must be taken to avoid contact withsuch materials. The sampling equipment is therefore fabricatedto appropriate high standards of vacuum integrity, and compo-nents in di
25、rect contact with UF6are made from nickel,high-nickel alloys, or materials having equivalent resistance toUF6corrosion. The formation of an inert fluoride layer is oftenan important feature of UF6corrosion resistance, and hence,internal surfaces are generally conditioned with a suitablefluorinating
26、agent, sometimes UF6itself.7.4 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
27、 material 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.7.5 If the sample bottles are taken for an analytical
28、needsuch as liquid UF6 subsampling for P10 tubes or liquid UF6transfer for FTIR quantification, it is recommended, in order tominimize the gas phase contribution to the sample bottle, to fillthe bottle with more than 10% of its total volume.8. Procedure for Sampling Directly from FilledContainers (s
29、ee Fig. 1)8.1 The equipment consists of a sample manifold that isconnected directly to the valve of the transport container andhas facilities for connecting one or more sample bottles. Thegraduated volume is appropriately sized so that when filledeither completely or visually to a predetermined leve
30、l it willcontain a known quantity of UF6. The graduated volume mayconsist of the manifold and associated pipework, or mayinclude an additional metering volume (pipette). The equip-ment may be designed to withdraw either single or multiplesample quantities of UF6at each operation. The total graduated
31、volume of the connected equipment (excluding the vacuumsystem) should not exceed the designated maximum fill vol-ume of the connected sample bottles. Certain valves may beremotely operated as necessary. The sampling equipment mustbe heated to prevent solidification of the UF6and may belocated within
32、 the same heated enclosure as the container. Thesample bottles may be heated separately to permit independentcooling, if necessary.8.2 Load the container to be sampled into the heatingenclosure (for example, autoclave) and attach the samplingequipment, including sample bottles. Evacuate and test the
33、equipment to ensure vacuum integrity.FIG. 1 Schematic Arrangement for Sampling Directly from aFilled ContainerC 1052 01 (2007)28.2.1 When local safety regulations permit, a container ofhot, liquid UF6may be loaded into the sampling equipment andthe sample bottles attached.8.3 Heat the bulk UF6for a
34、sufficient period to ensurehomogeneity in accordance with the procedure established forthe equipment (see 7.2). During heating, monitor and check thevapor pressure against the applicable pressure limit (if any) toensure compliance with the relevant specification and mainte-nance of a safe pressure l
35、evel. In case of overpressure, followappropriate procedures.8.4 When the conditions for homogeneity have been met,withdraw the appropriate quantity of liquid UF6into thegraduated volume. This is usually effected by changing theposition of the container in such a way, for example, by tiltingor turnin
36、g, that the UF6flows under the influence of gravityand any differential pressures established within the equip-ment. Restore the container to its original position leaving thegraduated volume filled with liquid UF6. This may be indicatedby the use of suitable temperature sensors or pressure trans-du
37、cers or strain gages.8.5 If the equipment is designed to withdraw a singlesample at each operation, open the appropriate sample valve toallow the UF6to flow into the sample bottle. Isolate the samplebottle from the sampling manifold.8.5.1 The first sample may be used to condition internalsurfaces of
38、 the equipment (see 7.3) by suitable manipulation ofthe vacuum system or rejected to prevent cross-contaminationfrom previously sampled materials or both (see 7.4).8.5.2 Take successive samples by repeating steps 8.4 and8.5 as necessary.8.6 If the equipment is designed to withdraw multiplesamples at
39、 each operation, transfer the samples to the samplebottles by operating the valves associated with the successivesample bottles in the appropriate sequence.8.7 At the completion of sampling, close the container valveand evacuate the sampling equipment through the vacuumsystem to remove residual UF6.
40、8.8 Fill the equipment to atmospheric pressure with dry gasand remove, identify, cap, and weigh the sample bottles. Localsafety regulations may demand that the UF6is allowed to cooland solidify (below atmospheric pressure) before this operationis carried out.9. Procedure for Sampling During Filling
41、of TransportContainers (see Fig. 2)9.1 The equipment consists of a sample manifold that hasfacilities for connecting one or more sample bottles and isconnected to the filling manifold between the main andsecondary (for example, transport) containers. The graduatedvolume is appropriately sized to con
42、tain the quantity of UF6required for a single sample and normally consists of themanifold and associated pipework itself or may include anadditional metering volume (pipette). The total graduatedvolume of the connected equipment (excluding the vacuumsystem) should not exceed the designated maximum f
43、ill vol-ume of the attached sample bottles. Certain valves may beremotely operated as necessary. Heat the sampling equipmentto prevent the solidification of UF6. The sample bottles may becontained in a separate enclosure to permit independent cool-ing if necessary (see 9.6).9.2 Conditions for homoge
44、neity must be met within the UF6main container immediately before the run-off to the secondary(for example, transport) container (see 7.2). This main con-tainer may typically be a plant vessel (for example, condenser)or another larger transport container (mother-container). Incase of the presence of
45、 particles in the UF6, careful attentionshould be taken when choosing the appropriate time forsampling because of rapid sedimentation.9.3 Attach the sampling equipment, including samplebottles, at the relevant location to the UF6runoff line. Evacuateand test the equipment to ensure vacuum integrity.
46、 Isolate thesample bottles from the sample manifold.9.4 Establish liquid transfer of UF6from the main containerto the secondary container.9.5 At an appropriate time, open the sampling valve andwithdraw the required quantity of UF6into the graduatedvolume. This may be indicated by the use of suitable
47、 tempera-ture sensors or pressure transducers or strain gages.9.6 Close the sampling valve and open the first samplebottle valve to transfer the sample. The equipment should bedesigned to allow transfers to take place using the influence ofgravity and differential pressures induced by temperaturegra
48、dients. For this purpose, it may be necessary to cool thereceiving sample bottles.9.6.1 The first sample may be used to condition internalsurfaces of the equipment (see 7.3) by suitable manipulation ofthe vacuum system or rejected to prevent cross-contaminationfrom earlier materials or both (see 7.4
49、).9.7 Isolate the sample bottle from the sampling manifold.FIG. 2 Schematic Arrangement for Sampling During the Filling ofa Transport ContainerC 1052 01 (2007)39.8 If successive samples are to be taken, repeat 9.5 and 9.6.If not, the volume of the pipette should be adapted so that thesample taken is representative of material transferred from themain cylinder.9.9 At the completion of sampling, close all the samplebottle valves. Any residual UF6in the equipment and samplinglines is either blown back using dry gas or is evacuated into aUF6trap. Close the sampling valve and evacuate
