1、Designation: C1742 10Standard Test Method forIsotopic Analysis of Uranium Hexafluoride by DoubleStandard Single-Collector Gas Mass Spectrometer Method1This standard is issued under the fixed designation C1742; the number immediately following the designation indicates the year oforiginal adoption or
2、, in the case of revision, the year of last revision. 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 is a quantitative test method applicable to deter-mining the mass percent
3、of uranium isotopes in uraniumhexafluoride (UF6) samples with235U concentrations between0.1 and 5.0 mass %.1.2 This test method may be applicable for the entire rangeof235U concentrations for which adequate standards areavailable.21.3 This test method is for analysis by a gas magnetic sectormass spe
4、ctrometer with a single collector using interpolation todetermine the isotopic concentration of an unknown samplebetween two characterized UF6standards.1.4 This test method is to replace the existing test methodcurrently published in Test Methods C761 and is used in thenuclear fuel cycle for UF6isot
5、opic analyses.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.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
6、establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3C761 Test Methods for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and Radiochemical Analysis ofUranium HexafluorideC787 Spe
7、cification for Uranium Hexafluoride for Enrich-mentC996 Specification for Uranium Hexafluoride Enriched toLess Than 5 %235U2.2 Other Document:USEC-651 Uranium Hexafluoride: A Manual of Good Han-dling Practices, Latest Revisions3. Summary of Test Method3.1 The unknown sample and two standards, whose2
8、35Umass percent bracket that of the unknown, are introduced insequence into the mass spectrometer and measurements aremade that are a function of the mol ratio of235U to the total ofthe other isotopes of uranium. These measurements, togetherwith the known composition of the standards, permit calcula
9、-tion of the235U composition of the sample by linear interpo-lation (1-6).3.2 The symmetrical sequence of sample-standard introduc-tions from low standard, sample, high standard, and thenreversed is designed to minimize biases resulting from instru-ment drift, sample interaction or memory, and the n
10、onlinearityof the relationship between the measured resistance ratios andthe true sample mol ratios. Corrections generally are notrequired for instrument memory.4. Significance and Use4.1 Uranium hexafluoride is a basic material used to preparenuclear reactor fuel. To be suitable for this purpose, t
11、hematerial shall meet the criteria for isotopic composition. Thistest method is designed to determine whether the materialmeets the requirements described in Specifications C787 andC996.4.2 ASTM Committee C26 Safeguards Statement:4.2.1 The material (uranium hexafluoride) to which this testmethod app
12、lies is subject to the nuclear safeguards regulationsgoverning its possession and use. The analytical procedure inthis test method has been designated as technically acceptablefor generating safeguards accountability data.4.2.2 When used in conjunction with the appropriate certi-fied reference mater
13、ials (CRMs), this procedure can demon-strate traceability to the national measurement base. However,1This test method 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 Oct. 1, 2010.
14、Published November 2010. DOI:10.1520/C174210.2This test method applies to the measurement of235U. It would also be able tomeasure minor isotopes using the same principle subject to appropriate validation bythe measurement laboratory.3For referenced ASTM standards, visit the ASTM website, www.astm.or
15、g, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.adherence to
16、this procedure does not automatically guaranteeregulatory acceptance of the regulatory safeguards measure-ments. It remains the sole responsibility of the user of this testmethod to ensure that its application to safeguards has theapproval of the proper regulatory authorities.5. Apparatus5.1 A mass
17、spectrometer is used with the following featuresand capabilities (2-7):5.1.1 An ion source with an accelerating voltage of approxi-mately 1.75kv.5.1.2 The sample inlet system shall have a minimum ofthree points for attachment of standards and samples, thenecessary valves to evacuate the sample lines
18、 and admit theUF6into the ion source, and a variable leak to control the flowof UF6into the ion source.5.1.3 A single ion collector (8) consisting of a high and lowsignal shall be used. The high-side current signal contains acentral slit, preferably adjustable, to permit passage of greaterthan 90 %
19、of the ions of the235U isotope (mass 330). The235U ions passing through the slit is called the low-side currentsignal.5.1.4 The measuring system shall provide a mole ratiomeasurement calculation from the low- and high-current sig-nal. Such a system usually consists of an amplifier and counterfor eac
20、h V-to-F convertor.5.1.5 The resolving power of the instrument should beshould be less than 5 % between Mass 330/333. This resolutionrequirement should be met with the collector slit widthadjusted to pass at least 90 % of the235U ion beam.5.2 Computer control for opening and closing valves, tim-ing
21、sequence and integrations of signals and data acquisitions.6. Procedure6.1 Prepare Sample and Standards:6.1.1 Select a high and low standard that bracket the235Umass percent of the sample.6.1.2 Attach sample and standard containers to the spec-trometer.6.1.3 Open and close the appropriate valves to
22、evacuate theair from the inlet system.6.1.4 Open the sample and standard containers individuallyto remove impurities that may bias the results or interfere withthe ionization. If necessary, freeze the UF6with ice water or amixture of crushed dry ice and isopropyl alcohol to permitlonger venting with
23、out losing large amounts of UF6.6.1.5 Permit the exhaust system to recover.6.1.6 Check to see if impurities have been sufficientlyremoved by introducing UF6into the ion source and observingpressure.6.1.7 If necessary, repeat 6.1.4 to 6.1.6 until samples havebeen sufficiently purified.6.2 Prepare Ins
24、trument:6.2.1 Ensure the instrument parameters are set so the235UF5+ion beam is focused through the slit on the high-sideplate onto the low side plate.6.2.2 Enter standard values and other information if neededfor calculations performed by the computer.6.2.3 For purposes of programming entry sequenc
25、es into thespectrometer, let the low standard be represented by A, theunknown sample by X, and the high standard by B.6.2.4 The most generic sequence to use in interpolating anunknown (X) between two standards is A, X, B or B, X, A.Combining an A, X, B with a B, X, A helps to eliminate bias asa resu
26、lt of residual amounts of UF6in the ion source from theprevious entry. A sequence of AXBBXAis designed to dothis. The data used in the precision and bias statement for thistest method were obtained using this sequence. Other se-quences of BXAAXB; AXBXA;orBXAXBare alsodesigned to help alleviate this
27、bias. Program the desiredsequence.6.2.5 Run the desired number of sequences for the analysis.7. Calculation7.1 For each entry, obtain a ratio of the low-side collectorplate charge (235UF5+) to the high-side collector plate charge(238UF5+,234UF5+, and236UF5+).7.2 For a sequence of A, X, B, B, X, A, f
28、ind the arithmeticmean of the two ratios for A, X, and B. Let:7.2.1 RA= mean of the ratios for the low standard (A),7.2.2 RX= mean of the ratios for the sample (X), and7.2.3 RB= mean of the ratios for the high standard (B).7.3 Calculate the ratio of differences, RD, as follows:RD5 RX2 RA!/RB2 RA! (1
29、)7.4 Calculate the sample mass ratio, HX, using linear inter-polation as follows:HX5 RDHB HA! 1 HA(2)where:HX= mass ratio of235U to the other U isotopes in thesample,HA= mass ratio of235U to the other U isotopes in the lowstandard, andHB= mass ratio of235U to the other U isotopes in the highstandard
30、.7.5 Calculate the mass %235U in the sample as follows:Mass %235U 5 100 Hx/100 1 Hx! (3)8. Precision and Bias8.1 Three characterized UF6isotopic standards were run ascontrol samples for this test method. All standards weretraceable to recognized national standards. The standard des-ignations, functi
31、ons, and reference values are listed in Table 1.8.2 Because of difficulties in movement and ownership ofnuclear materials, the estimate of reproducibility was obtainedby treating the spectrometers as the different laboratories. EachTABLE 1 Reference Materials and Their Assigned ValuesIdentity Functi
32、on235U Mass %ValueAST 122-3 Depleted standard 0.52393ST 128 Normal standard 0.71104ST 26 Enriched standard 4.4601AThe uncertainty in the assigned values, expressed as 3 3 %RSD, is60.066 %.C1742 102of the three standards was analyzed over several years bydifferent analysts using different spectromete
33、rs in the samelaboratory resulting in a total of 30 test results for eachstandard. The one analyst design was impractical because ofthe accumulation of data over such a large period of time. Thecontribution of variation as a result of different analysts wasminimal. Pumping down the instrument and re
34、starting thespectrometer by computer were the basic components of thisvariation.8.3 For each reference material, the mean, repeatabilitystandard deviation (SDr), relative repeatability standard devia-tion (%RSDr), reproducibility standard deviation (SDR), rela-tive reproducibility standard deviation
35、 (%RSDR), repeatabilitylimit, reproducibility limit, and % difference was calculated.The estimated precision results for the three characterized UF6isotopic standards are shown in Table 2. Reproducibility resultswere obtained by treating each of the mass spectrometers asseparate laboratories. This s
36、hould be taken into account whenconsidering the results.8.4 Precision4The precision was calculated based onmass percent units. The repeatability percent RSD (singlespectrometer) was determined to be 0.017 % and was typicallyconsistent for all levels of mass percent. The reproducibilitypercent RSD (b
37、etween spectrometers) was calculated to be0.018 %. The closeness in agreement between the repeatabilityand reproducibility values is expected since statistical analysisconcluded no significant differences between mass spectrom-eter results.8.5 BiasThe observed percent difference was calculatedfor ea
38、ch standard as an indication of bias and the estimatesappear in Table 2. The % difference (averaged over the threestandards) was determined to be -0.009 % indicating an overallaccuracy of 99.991 %.9. Keywords9.1 double standard; isotopic; mass spectrometry; singlecollector uranium hexafluoride4Suppo
39、rting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:C26-1013.C1742 103REFERENCES(1) Kauffman, G. F. and Tabor, C. D., “Isotopic Measurement of Uraniumby Mass Spectrometry,” Proceedings of IAEA Symposium on NuclearMaterial Management, IARG
40、A, Vienna, 1966.(2) Tabor, C. D., “Mass Spectrometric Determination of U-235 in Ura-nium Hexafluoride Using the Double-Standard Interpolative Tech-nique,” TID-7029.(3) Tabor, C. D., “Mass Spectrometry for Uranium Isotopic Measure-ments,” IAEA, Rev. Ser., No. 5, 1960.(4) Kauffman, G. F. and Christoph
41、er, N. F., “Uranium HexafluorideIsotopic Measurements Using an Interpolative Method,” GAT-291,Goodyear Atomic Corp., Portsmouth, OH, Nov. 30, 1960.(5) Kauffman, G. F. and Tabor, C. D., “Precision Mass SpectrometricDetermination of Uranium Isotopic Composition,” GAT-T-664, Good-year Atomic Corp., Por
42、tsmouth, OH, May 21, 1959.(6) Smith, R. L., Shields, W. R., and Tabor, C. D., “An InterpolativeMethod of Assaying UF6with the Isotopic Mass Spectrometer,”GAT-171, Rev. 1, Goodyear Atomic Corp., Portsmouth, OH, May 21,1956.(7) Nier, A. O., “Mass Spectrometer for Isotopic and Gas Analysis,”Review of S
43、cientific Instr., Vol 18, 1947, pp. 398411.(8) Langdon, A. and Kermicle, H. A., “An Automatic, Relative MassSpectrometer for Uranium Isotopes,” K-1444, Union Carbide Corp.,Nuclear Division, Oak Ridge Gaseous Diffusion Plant, Oak Ridge, TN,May 20, 1963.ASTM International takes no position respecting
44、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, are entirely their own responsibility.This standard
45、 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 for revision of this standard or for additional standardsand should be addressed to ASTM International
46、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 hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This
47、 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 may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax),
48、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/).TABLE 2 Precision and Bias Test Results in235U Mass Percent UnitsReference ValuesResults 0.52393235UMass %Control0.7
49、1104235UMass %Control4.46010235UMass %ControlAverage, %Sample size 30 30 30 . . .Mean 0.52391 0.71098 4.45950 . . .SDrA0.000093 0.000147 0.00058 . . .SDRB0.0001 0.000147 0.00058 . . .%RSDrC0.018 0.021 0.013 0.017%RSDRD0.019 0.021 0.013 0.018Repeatability limit, %E0.050 0.059 0.036 0.048Reproducibility limit, %F0.053 0.059 0.036 0.049% DifferenceG-0.0038 -0.0084 -0.0135 -0.009ASDr= repeatability standard deviation (single spectrometer).BSDR= reproducibility standard deviation (different spectrometers).C%RSDr= relative repeatability standard deviation (percent) = 100 (SDr/
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