1、Designation: C1742 10C1742 17Standard 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 ado
2、ption or, 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 determining the mass p
3、ercent of uranium isotopes in uranium hexafluoride(UF6) samples with 235U concentrations between 0.1 and 5.0 mass %.1.2 This test method may be applicable for the entire range of 235U concentrations for which adequate standards are available.21.3 This test method is for analysis by a gas magnetic se
4、ctor mass spectrometer with a single collector using interpolation todetermine the isotopic concentration of an unknown sample between two characterized UF6 standards.1.4 This test method is to replace the existing test method currently published in Test Methods C761 and is used in the nuclearfuel c
5、ycle for UF6 isotopic analyses.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user
6、of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principl
7、es for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3C761 Test Methods for Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical A
8、nalysis of UraniumHexafluorideC787 Specification for Uranium Hexafluoride for EnrichmentC859 Terminology Relating to Nuclear MaterialsC996 Specification for Uranium Hexafluoride Enriched to Less Than 5 % 235UC1068 Guide for Qualification of Measurement Methods by a Laboratory Within the Nuclear Indu
9、stry2.2 Other Document:USEC-651 Uranium Hexafluoride: A Manual of Good Handling Practices, Latest Revisions3. Terminology3.1 Except as otherwise defined herein, definitions of terms are as given in Terminonlogy C859.4. Summary of Test Method4.1 The unknown sample and two standards, whose 235U mass p
10、ercent bracket that of the unknown, are introduced in sequenceinto the mass spectrometer and measurements are made that are a function of the mol ratio of 235U to the total of the other isotopes1 This test method is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct
11、 responsibility of Subcommittee C26.05 on Methods of Test.Current edition approved Oct. 1, 2010June 1, 2017. Published November 2010June 2017. Originally approved in 2010. Last previous edition approved in 2010 asC1742 10. DOI: 10.1520/C174210.10.1520/C1742-17.2 This test method applies to the measu
12、rement of 235U. It would also be able to measure minor isotopes using the same principle subject to appropriate validation by themeasurement laboratory.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Sta
13、ndardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possibl
14、e to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West
15、Conshohocken, PA 19428-2959. United States1of uranium. These measurements, together with the known composition of the standards, permit calculation of the 235Ucomposition of the sample by linear interpolation (1-6).4.2 The symmetrical sequence of sample-standard introductions from low standard, samp
16、le, high standard, and then reversedis designed to minimize biases resulting from instrument drift, sample interaction or memory, and the nonlinearity of therelationship between the measured resistance ratios and the true sample mol ratios. Corrections generally are not required forinstrument memory
17、.5. Significance and Use5.1 Uranium hexafluoride is a basic material used to prepare nuclear reactor fuel. To be suitable for this purpose, the materialshall meet the criteria for isotopic composition. This test method is designed to determine whether the material meets therequirements described in
18、Specifications C787 and C996.5.2 ASTM Committee C26 Safeguards Statement: Fitness for Purpose of Safeguards and Nuclear Safety ApplicationsMethodsintended for use in safeguards and nuclear safety applications shall meet the requirements specified by Guide C1068 for use in suchapplications.5.2.1 The
19、material (uranium hexafluoride) to which this test method applies is subject to the nuclear safeguards regulationsgoverning its possession and use. The analytical procedure in this test method has been designated as technically acceptable forgenerating safeguards accountability data.5.2.2 When used
20、in conjunction with the appropriate certified reference materials (CRMs), this procedure can demonstratetraceability to the national measurement base. However, adherence to this procedure does not automatically guarantee regulatoryacceptance of the regulatory safeguards measurements. It remains the
21、sole responsibility of the user of this test method to ensurethat its application to safeguards has the approval of the proper regulatory authorities.6. Apparatus6.1 A mass spectrometer is used with the following features and capabilities (2-7):6.1.1 An ion source with an accelerating voltage of app
22、roximately 1.75kv.6.1.2 The sample inlet system shall have a minimum of three points for attachment of standards and samples, the necessaryvalves to evacuate the sample lines and admit the UF6 into the ion source, and a variable leak to control the flow of UF6 into theion source.6.1.3 Asingle ion co
23、llector (8) consisting of a high and low signal shall be used. The high-side current signal contains a centralslit, preferably adjustable, to permit passage of greater than 90 % of the ions of the 235U isotope (mass 330).The 235U ions passingthrough the slit is called the low-side current signal.6.1
24、.4 The measuring system shall provide a mole ratio measurement calculation from the low- and high-current signal. Sucha system usually consists of an amplifier and counter for each V-to-F convertor.6.1.5 The resolving power of the instrument should be should be less than 5 % between Mass 330/333. Th
25、is resolutionrequirement should be met with the collector slit width adjusted to pass at least 90 % of the 235U ion beam.6.2 Computer control for opening and closing valves, timing sequence and integrations of signals and data acquisitions.7. Hazards7.1 Uranium hexafluoride (UF6) reacts vigorously w
26、ith water, releasing corrosive hydrofluoric acid and toxic uranyl fluoride.Use sufficient ventilation or respiratory protection to avoid breathing fumes. Use appropriate personal protective equipment suchas gloves, eye, and face protection. Consult the Safety Data Sheet for additional information.8.
27、 Procedure8.1 Prepare Sample and Standards:8.1.1 Select a high and low standard that bracket the 235U mass percent of the sample.8.1.2 Attach sample and standard containers to the spectrometer.8.1.3 Open and close the appropriate valves to evacuate the air from the inlet system.8.1.4 Open the sample
28、 and standard containers individually to remove impurities that may bias the results or interfere with theionization. If necessary, freeze the UF6 with ice water or a mixture of crushed dry ice and isopropyl alcohol to permit longerventing without losing large amounts of UF6.8.1.5 Permit the exhaust
29、 system to recover.8.1.6 Check to see if impurities have been sufficiently removed by introducing UF6 into the ion source and observing pressure.8.1.7 If necessary, repeat 6.1.48.1.4 to 6.1.68.1.6 until samples have been sufficiently purified.8.2 Prepare Instrument:8.2.1 Ensure the instrument parame
30、ters are set so the 235UF5+ ion beam is focused through the slit on the high-side plate ontothe low side plate.8.2.2 Enter standard values and other information if needed for calculations performed by the computer.C1742 1728.2.3 For purposes of programming entry sequences into the spectrometer, let
31、the low standard be represented by A, theunknown sample by X, and the high standard by B.8.2.4 The most generic sequence to use in interpolating an unknown (X) between two standards is A,X,B or B,X,A. Combiningan A,X,B with a B,X,A helps to eliminate bias as a result of residual amounts of UF6 in th
32、e ion source from the previous entry. Asequence of AXBBXA is designed to do this. The data used in the precision and bias statement for this test method were obtainedusing this sequence. Other sequences of BXAAXB; AX BXA; or BXAXB are also designed to help alleviate this bias. Program thedesired seq
33、uence.8.2.5 Run the desired number of sequences for the analysis.9. Calculation9.1 For each entry, obtain a ratio of the low-side collector plate charge (235UF5+) to the high-side collector plate charge (238UF5+,234UF5+, and 236UF5+).9.2 For a sequence of A,X,B, B,X,A, find the arithmetic mean of th
34、e two ratios for A,X, and B. Let:9.2.1 RA = mean of the ratios for the low standard (A),9.2.2 RX = mean of the ratios for the sample (X), and9.2.3 RB = mean of the ratios for the high standard (B).9.3 Calculate the ratio of differences, RD, as follows:RD 5RX 2RA!/RB 2RA! (1)9.4 Calculate the sample
35、mass ratio, HX, using linear interpolation as follows:HX 5RD HB 2HA!1HA (2)where:HX = mass ratio of 235U to the other U isotopes in the sample,HA = mass ratio of 235U to the other U isotopes in the low standard, andHB = mass ratio of 235U to the other U isotopes in the high standard.9.5 Calculate th
36、e mass % 235U in the sample as follows:Mass% 235U 5100 Hx/1001Hx! (3)10. Precision and Bias10.1 Three characterized UF6 isotopic standards were run as control samples for this test method. All standards were traceableto recognized national standards. The standard designations, functions, and referen
37、ce values are listed in Table 1.10.2 Because of difficulties in movement and ownership of nuclear materials, the estimate of reproducibility was obtained bytreating the spectrometers as the different laboratories. Each of the three standards was analyzed over several years by differentanalysts using
38、 different spectrometers in the same laboratory resulting in a total of 30 test results for each standard. The one analystdesign was impractical because of the accumulation of data over such a large period of time. The contribution of variation as aresult of different analysts was minimal. Pumping d
39、own the instrument and restarting the spectrometer by computer were the basiccomponents of this variation.10.3 For each reference material, the mean, repeatability standard deviation (SDr), relative repeatability standard deviation(%RSDr), reproducibility standard deviation (SDR), relative reproduci
40、bility standard deviation (%RSDR), repeatability limit,reproducibility limit, and % difference was calculated. The estimated precision results for the three characterized UF6 isotopicstandards are shown in Table 2. Reproducibility results were obtained by treating each of the mass spectrometers as s
41、eparatelaboratories. This should be taken into account when considering the results.10.4 Precision4The precision was calculated based on mass percent units. The repeatability percent RSD (singlespectrometer) was determined to be 0.017 % and was typically consistent for all levels of mass percent.The
42、 reproducibility percent4 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:C26-1013.TABLE 1 Reference Materials and Their Assigned ValuesIdentity Function 235U Mass %ValueAST 122-3 Depleted standard 0.52393ST 128 Normal standard
43、0.71104ST 26 Enriched standard 4.4601A The uncertainty in the assigned values, expressed as 3 %RSD, is 0.066 %.C1742 173RSD (between spectrometers) was calculated to be 0.018 %. The closeness in agreement between the repeatability andreproducibility values is expected since statistical analysis conc
44、luded no significant differences between mass spectrometer results.10.5 BiasThe observed percent difference was calculated for each standard as an indication of bias and the estimates appearin Table 2. The % difference (averaged over the three standards) was determined to be -0.009 % indicating an o
45、verall accuracy of99.991 %.11. Keywords11.1 double standard; isotopic; mass spectrometry; single collector uranium hexafluorideREFERENCES(1) Kauffman, G. F. and Tabor, C. D., “Isotopic Measurement of Uranium by Mass Spectrometry,” Proceedings of IAEASymposium on Nuclear MaterialManagement, IARGA, Vi
46、enna, 1966.(2) Tabor, C. D., “Mass Spectrometric Determination of U-235 in Uranium Hexafluoride Using the Double-Standard InterpolativeTechnique,”TID-7029.(3) Tabor, C. D., “Mass Spectrometry for Uranium Isotopic Measurements,” IAEA, Rev. Ser., No. 5, 1960.(4) Kauffman, G. F. and Christopher, N. F.,
47、 “Uranium Hexafluoride Isotopic Measurements Using an Interpolative Method,” GAT-291, GoodyearAtomicCorp., Portsmouth, OH, Nov. 30, 1960.(5) Kauffman, G. F. and Tabor, C. D., “Precision Mass Spectrometric Determination of Uranium Isotopic Composition,” GAT-T-664, Goodyear AtomicCorp., Portsmouth, OH
48、, May 21, 1959.(6) Smith, R. L., Shields, W. R., and Tabor, C. D., “An Interpolative Method of Assaying UF6 with 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 Scientif
49、ic Instr., Vol 18, 1947, pp. 398411.(8) Langdon, A. and Kermicle, H. A., “An Automatic, Relative Mass Spectrometer for Uranium Isotopes,” K-1444, Union Carbide Corp., NuclearDivision, Oak Ridge Gaseous Diffusion Plant, Oak Ridge, TN, May 20, 1963.TABLE 2 Precision and Bias Test Results in 235U Mass Percent UnitsReference ValuesResults 0.52393 235UMass %Control0.71104 235UMass %Control4.46010 235UMass %ControlAverage, %Sample size 30 30 30 . . .Mean 0.52391 0.71098 4.45950 . . .SDrA 0.000093 0.000147 0.00058 . . .SDRB 0.0001 0.000147 0.00058 . . .%RSDrC 0.018 0.021 0.
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