1、Designation: C 1429 99 (Reapproved 2009)1Standard Test Method forIsotopic Analysis of Uranium Hexafluoride by Double-Standard Multi-Collector Gas Mass Spectrometer1This standard is issued under the fixed designation C 1429; the number immediately following the designation indicates the year oforigin
2、al adoption 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.1NOTESection 1.3 was updated editorially in July 2009.1. Scope1.1 This test m
3、ethod covers a quantitative test methodapplicable to determining the mass percent of uranium isotopesin uranium hexafluoride (UF6) samples. This method as de-scribed is for concentrations of235U between 0.1 and 10mass %, and234U and236U between 0.0001 and 0.1 mass %.1.2 This test method is for labor
4、atory analysis by a gas massspectrometer with a multi-collector.1.3 This standard complements Test Methods C 761, thedouble-standard method for gas mass spectrometers using asingle collector, by providing a method for spectrometers usinga multi-collector.1.4 This standard does not purport to address
5、 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 determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 761 Test Method
6、s for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and Radiochemical Analysis ofUranium HexafluorideC 787 Specification for Uranium Hexafluoride for Enrich-mentC 996 Specification for Uranium Hexafluoride Enriched toLess Than 5 %235UC 1215 Guide for Preparing and Interpreting Precision and
7、Bias Statements in Test Method Standards Used in theNuclear Industry3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 A standard, nthe low-value standard of a standardpair that brackets the sample.3.1.2 B standard, nthe high-value standard of a standardpair that brackets the sam
8、ple.3.1.3 determination, na single isotopic value, calculatedfrom a sequence of ratios; the most basic isotopic valuecalculated.3.1.4 Lagranges interpolation formula, na mathematicalequation designed to estimate values between two or moreknown values.3.1.5 run, na completed, six-entry symmetrical se
9、quenceconsisting of A standard, sample, B standard, B standard,sample, and A standard from which a determination can becalculated for one or more isotopes.3.1.6 standard spread, nthe difference between the highand low standards; sometimes called standard range.3.1.7 test result, na reported value; t
10、he mean of two ormore determinations.4. Summary of Test Method4.1 Uranium hexafluoride gas is introduced into an ioniza-tion source. The resulting ions are accelerated down the flighttube into the magnetic field. The magnetic field separates theions into ion beams in accordance with the m/e ratio. F
11、ourcollectors are stationed so the234UF5+,235UF5+,236UF5+, and238UF5+ion beams strike individual collectors.4.2 Two standards are chosen whose values bracket thedesired isotope of the sample. The sample and two standardsare introduced in a six-entry, symmetrical sequence. Then,measurements are taken
12、 that give the mole ratio of the desiredisotope to238U.1This test method is under the jurisdiction of ASTM CommitteeC26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved June 1, 2009. Published July 2009. Originally approvedin 199
13、9. Last previous edition approved in 2004 as C 1429 99 (2004).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
14、.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.3 Through Lagranges interpolation formula, these mea-surements are used to calculate the mass percent of the desiredisotope. If standards are available that bracket all isotopes, the
15、nthe234U,235U, and236U mass percents are calculated from thesame six-entry run.4.4 The results of two six-entry, symmetrical-sequence runsare averaged to find test results for each isotope. The238U masspercent is obtained by subtraction.5. Significance and Use5.1 Uranium hexafluoride used to produce
16、 nuclear-reactorfuel must meet certain criteria for its isotopic composition.This test method may be used to help determine if samplematerials meet the criteria described in Specifications C 787and C 996.6. Apparatus6.1 Mass spectrometer with the following features andcapabilities:6.1.1 An ion sourc
17、e with an accelerating voltage of approxi-mately 8 kV,6.1.2 A resolving power of greater than or equal to 500,6.1.3 A minimum of three points of attachment for stan-dards or samples,6.1.4 An ion collection system consisting of four collectorcups stationed to collect234UF5+,235UF5+,236UF5+, and238UF5
18、+ions,6.1.5 An ion-current amplifier for each collector cup,6.1.6 A voltage-to-frequency (V-to-F) converter for eachamplifier,6.1.7 A counter for each V-to-F converter, and6.1.8 Computer control over opening and closing valves, thetiming, and the integration of analytical sequences.7. Procedure7.1 S
19、elect standards:7.1.1 Choose high and low standards that bracket thesample isotope(s) being evaluated. If the mass percentof234U,235U, and236U are all desired, then the two standardsmust bracket each of the three isotopes to permit calculation ofall isotopes for every run.7.1.2 If standards that bra
20、cket all isotopes are unavailable,analyze the isotope(s) bracketed by the originally selectedstandards, then select other standards to run the remainingisotope(s).7.2 Prepare Sample and Standards:7.2.1 Attach sample and standard containers to the spec-trometer.7.2.2 Open and close the appropriate va
21、lves to evacuate theair from the inlet system.7.2.3 Open the sample and standard containers individuallyand vent the gas phase to the cold trap. This is to removeimpurities that may bias the results or interfere with theionization. If necessary, freeze the UF6with ice water or amixture of crushed dr
22、y ice and isopropyl alcohol to permitlonger venting without losing large amounts of UF6.7.2.4 Permit exhaust system pressure to recover.7.2.5 Check to see if impurities have been sufficientlyremoved by introducing UF6into the ion source and observingpressure, or exhausting through the cold trap and
23、observingpressure on the other side, or any other suitable means.7.2.6 If necessary, repeat 7.2.3-7.2.5 until samples are clean.7.3 Prepare Instrument:7.3.1 Adjust instrument parameters to focus ion beams inproper collectors and maximize the238UF5+current reading.7.3.2 Enter standard values and othe
24、r information if neededfor calculations performed by computer.7.3.3 Program the spectrometer to run two of the followingsix-entry, symmetrical sequences: low standard, sample, highstandard, high standard, sample, low standard.7.4 Run the Analysis:7.4.1 Obtain measurements from all four collectors du
25、ringeach entry.8. Calculation8.1 Perform the following operations for each of the234U,235U, and236U isotopes:8.1.1 For each entry, obtain a ratio by dividing the UF5+ioncount of the desired isotope by the238UF5+ion count.8.1.2 Find the mean of the two low standard ratios anddesignate this A.8.1.3 Fi
26、nd the mean of the two sample ratios and designatethis X.8.1.4 Find the mean of the two high standard ratios anddesignate this B.NOTE 1In a six-entry symmetrical run sequence,r11 r6! /25 A (1)r21 r5! /25 X (2)r31 r4! /25 B (3)where:rn= the ratio from the nthentry.8.1.5 Find the mass percent ratio of
27、 the low value standard(A standard) by dividing the mass percent of the desired isotopeby the mass percent238U.EA5 mass %234U / mass %238U (4)HA5 mass %235U / mass %238U (5)YA5 mass %236U / mass %238U (6)8.1.6 Find the equivalent mass percent ratio for the highvalue standard (B standard.) Label it e
28、ither EB, HB,orYB.8.1.7 Find the difference (D) between the mass percentratios of the A and B standards.NOTE 2EB EA= DE, HB HA= DH, and YB YA= DY8.1.8 Find the mass percent ratio (desired isotope/238U) ofthe sample by calculating EX, HX,orYXas follows:EX5 X 2 A! / B 2 A! DE1 EA(7)HX5 X 2 A! / B 2A!
29、DH1 HA(8)YX5 X 2 A! / B 2 A! DY1 YA(9)NOTE 3Calculations in 8.1.8 are based on an algebraic manipulationof Lagranges interpolation formula using two known values of a function.8.2 Calculate the mass percent as follows:C 1429 99 (2009)12e 5 100%EX/ 1 1 EX1 HX1 YX! (10)x 5 100%HX/ 1 1 EX1 HX1 YX! (11)
30、y 5 100%YX/ 1 1 EX1 HX1 YX! (12)where:e = mass %234U,x = mass %235U, andy = mass %236U.8.3 Average a minimum of two determinations for each testresult.8.4 Find the mass percent238U by subtracting the masspercent of the other isotopes from 100 %.9. Precision and Bias9.1 Seven standards traceable to N
31、ational Institute of Stan-dards and Technology (NIST) were selected as referencevalues. Two pairs of standards, also traceable to NIST, werechosen to evaluate the234U,235U, and236U mass percent valuesof the seven reference standards. These standard pairs wereobtained by selecting a low standard and
32、two high standards tocreate one standard spread that was narrower for all three of thedesired isotopes and one standard spread that was wider for allthree of the desired isotopes. The234U and236U referencevalues assigned to all of these standards were determined bythermal mass spectrometer (see Tabl
33、e 1) with the exception ofthe mass percent236U value assigned to G015-1. This valuewas obtained on a single-collector gas-phase mass spectrom-eter. The235U reference values were assigned through acombination of thermal and gas-phase analysis.9.2 The test deviated from single-day design because of th
34、eneed for a large number of test results for statistical purposes.However, each set of data for a specific combination ofreference value, standard pair, and mass spectrometer wasobtained within a 24-h period. Each reference standard was runby double-standard method 60 consecutive times for each oftw
35、o standard pair on each of three mass spectrometers. Everyrun yielded three determinations, one for each isotope. Twoconsecutive determinations were then averaged for a test result.This produced a test result for each isotope after every twoconsecutive runs. The completion of each reference standard
36、analysis yielded 30 test results per combination of spectrometerand standard pair for each of the234U,235U, and236U isotopes.The combined test data for all isotopes of all referencestandards yielded 7560 test determinations and 3780 testresults. These data were collected over a period of severalmont
37、hs.9.3 The one-analyst design was impractical because of theneed to accumulate such a large amount of data in as short atime as possible. After a reference standard was attached to aspectrometer, all the data for that combination of referencestandard and standard pair were obtained before the refere
38、ncestandard was detached from the spectrometer. The contributionto variation due to different analysts should have been minimal.Pumping down the instrument and restarting the spectrometerby computer were the basic components of that variation.9.4 Due to the difficulties in movement and ownership ofn
39、uclear materials, as referred to in Section 1.4 of GuideC 1215, the reproducibility was obtained by treating the threespectrometers as three different laboratories. This should betaken into account when considering the reproducibility re-sults.9.5 Precision3The precision was calculated based onmass
40、percent units. The repeatability percent RSD for the235Uisotope was determined to be 0.006 % and was typicallyconsistent for all levels of mass percent. The reproducibilitypercent RSD for the235U isotope was determined to be0.010 % and tended to decrease as the assay increased.9.5.1 The repeatabilit
41、y percent RSD for the234U isotopewas determined to be 0.411 % and typically decreased asthe234U mass percent increased. The reproducibility percentRSD for the234U isotope was determined to be 0.722 %.9.5.2 The average repeatability percent RSD for the236Uisotope was determined to be 0.344 % and tend
42、ed to decreaseas the236U assay increased. The reproducibility percent RSDfor the236U isotope was determined to be 1.664 % and tendedto decrease as the236U assay increased. The precision resultsfor the three uranium isotopes are listed in Table 2.9.6 BiasThe observed percent bias was calculated based
43、on mass percent units. The observed percent bias for the235Uisotope was determined to be 0.003 %. The observed percentbias for the234U isotope was determined to be 0.810 %. Theobserved percent bias for the236U isotope was determined tobe 3.711 %. The235U and234U data indicate no significant biasin t
44、he method. The236U data indicate there may be a slight biasfor that isotope. The bias results are listed in Table 2.3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: C26-1008.TABLE 1 Reference Materials Used in the Test and Their
45、Assigned ValuesIdentity Function234U mass %235U mass %236U mass %G005 low std 0.0026 0.48347 0.0027G006 reference 0.0040 0.61074 0.0060G0101 reference 0.0052 0.99151 0.0077G012 reference 0.0096 1.2250 0.0152AG0151 reference 0.0060 1.5139 0.0152AG020-1 reference 0.0156 2.0123 0.0039G025 reference 0.0
46、204A2.4719 0.0018BG0301 reference 0.0224A3.0066 0.0040G030 high std 0.0186 3.0072 0.0108G0501 high std 0.0264 4.9457 0.0369AThese values are outside the bracket of the narrow standard spread, and onlythe data obtained from the wider standard pair are used to determine the precisionand bias.BThis val
47、ue is not within the bracket of either standard pair, and the dataobtained for this value were not used to determine the precision and bias. Thecertainty in the assigned values, expressed as 3 3 % RSD is 6 2.2921 % for234U,6 0.0646 % for235U, and 6 2.7263 % for236U.TABLE 2 Precision and Bias Test Re
48、sults in Mass Percent UnitsIsotope %BiasASrB%RSDrCSRD%RSDRE235U 0.003 0.00010 0.006 0.00014 0.010234U 0.810 0.000032 0.411 0.000085 0.722236U 3.711 0.000026 0.344 0.000120 1.664A%Bias = (bias/reference value) 3 100 %BSr= repeatability standard deviationC%RSDr= %RSD for repeatabilityDSR= reproducibil
49、ity standard deviationE%RSDR= %RSD for reproducibilityN = 1260 for235U, 1080 for234U, 900 for236UC 1429 99 (2009)1310. Keywords10.1 double-standard; isotopic; mass spectrometer; multi-collector; spectrometer; uranium hexafluorideASTM 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 rights, and the riskof infringement of such rights, are en
