1、Designation: C 1456 00Standard Test Method forthe Determination of Uranium or Gadolinium, or Both, inGadolinium Oxide-Uranium Oxide Pellets or by X-RayFluorescence (XRF)1This standard is issued under the fixed designation C 1456; the number immediately following the designation indicates the year of
2、original adoption or, in the case of revision, the year of last 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 standard describes the steps necessary for theprepara
3、tion and analysis by X-ray fluorescence (XRF) ofgadolinium and/or uranium in gadolinium oxide-uranium ox-ide pellets or powders.1.2 This method requires the use of appropriate internalstandard(s). Care must be taken to ascertain that samplesanalyzed by this method do not contain the internal standar
4、delement(s) or that this contamination has been corrected formathematically whenever present. Such corrections are notaddressed in this standard.1.3 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 stand
5、ard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tions are given in Section 8 and various notes throughout themethod.2. Referenced Documents2.1 ASTM Standards:C 982 Guide for Selecting Components for Ge
6、neric EnergyDispersive X-Ray Fluorescence (XRF) Systems2C 1118 Guide for Selecting Components for Wavelength-Dispersive X-Ray Fluorescence (XRF) Systems2D 1193 Specification for Reagent Water3E 135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related Materials43. Terminology3.1
7、DefinitionsFor definitions of terms used in this guide,see Terminology E 135.3.2 Symbol:LiTB 5 lithium tetraborate (see 7.4).4. Summary of Test Method4.1 Solution or pellet standards containing the equivalent of110 % gadolinium oxide and 9099 % uranium oxide andappropriate internal standards are pla
8、ced in the sample holderof a x-ray spectrometer and exposed to an x-ray beam capableof exciting the uranium and gadolinium L-a emission lines andthe appropriate emission line for the internal standard. Theintensities generated are measured by an appropriate detector.The intensity ratio values obtain
9、ed from this data are used tocalibrate the x-ray analyzer.4.2 Samples are prepared in the same manner as thestandards and analyzed using conditions and curves generatedfrom those standards.NOTE 1Yttrium and strontium have been used successfully as internalstandards for uranium and samarium for gadol
10、inium. Scatter lines alsohave been used as internal standard lines (1).5An explanation of internalstandard method is found in several sources (2, 3).5. Significance and Use5.1 This guide is applicable to samples containing 2 to 10 %gadolinium oxide and 90 to 98 % uranium oxide on the “asreceived” ba
11、sis. The method may be used to determineconcentration of either uranium, gadolinium, or both.5.2 Either wavelength-dispersive or energy-dispersive x-rayfluorescence systems may be used provided the softwareaccompanying the system is able to accommodate the use ofinternal standards.6. Apparatus6.1 X-
12、Ray SpectrometerSee Guide C 982 or GuideC 1118 for the selection of the X-ray spectrometer. The methodis valid for either energy-dispersive or wavelength-dispersivesystems.6.2 Sample Cups/HoldersPrepare liquid sample cups forthe x-ray spectrometer as described by the manufacturer.Vented, disposable
13、sample cups with snap-on caps are satis-factory for most such analyses. Such cups decrease thelikelihood of contamination between samples. Sample holdersfor fused pellets should keep any pellet chips from getting intothe moving parts of the instrument.6.3 Window FilmPolyester, polyethylene, and poly
14、propy-lene films have been used successfully as the film window for1This guide is under the jurisdiction of ASTM Committee C-26 on Nuclear FuelCycle and is the direct responsibility of Subcommittee C-26.05 on Methods of Test.Current edition approved Feb. 10, 2000. Published March 2000.2Annual Book o
15、f ASTM Standards, Vol 12.01.3Annual Book of ASTM Standards, Vol 11.01.4Annual Book of ASTM Standards, Vol 03.05.5The boldface numbers in parentheses refer to the list of references at the end ofthis standard.1Copyright ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.cups
16、 or holders, or both. Tests should be performed todetermine the serviceability of any film chosen before insertioninto the instrument.6.4 Solution Dispenser (optional)The dispenser for theinternal standard solution, if used, should be capable ofreproducibility dispensing the internal standard soluti
17、on to alevel of 0.1 % relative standard deviation of the volumedispensed.6.5 Muffle Furnace, 1100C capacity.7. Reagents and Materials7.1 Purity of MaterialsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of
18、the Committee ofAnalytical Reagents of the American Chemical Society wheresuch specifications are available.6Other grades may be usedprovided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.2 Purity of Wate
19、rUnless otherwise indicated, referencesto water shall mean reagent water conforming to SpecificationD 1193.7.3 Gadolinium Oxide, Gd2O3It is recommended that thestandards be prepared using same batch as in pellets/powder.7.4 Lithium Tetraborate, Li2B4O7, fusion grade.7.5 Nitric Acid, HNO3, concentrat
20、ed (70 %).7.6 Samarium Oxide, Sm2O3, or other suitable internalstandard for gadolinium (see Note 1).7.7 Uranium Oxide, U3O8, NBL CRM-129 (or equivalent)(4).NOTE 2High purity UO2may be used if certification of uraniumanalysis is not required.7.8 Yttrium Oxide, Y2O3, or other suitable internal standar
21、dfor uranium (see Note 1).8. Technical Precautions8.1 XRF equipment analyzes by the interaction of ionizingradiation with the sample. Applicable safety regulations andstandard operating procedures must be reviewed prior to theuse of such equipment. All modern XRF spectrometers areequipped with safet
22、y interlocks to prevent accidental penetra-tion of the X-ray beam by the user. Do NOT override theseinterlocks without proper training. (See NBS Handbook 111.)8.2 Instrument performance may be influenced by environ-mental factors such as heat, vibration, humidity, dust, strayelectronic noise and lin
23、e voltage stability. These factors andperformance characteristics should be reviewed prior to use ofthis standard.9. Preparation of Apparatus9.1 Chamber EnvironmentThe liquid standards andsamples used in this method are corrosive. Some fumes will beemitted from the sample cups. These fumes may be de
24、trimentalto the spectrometer chamber. It is desirable to flush thischamber with an inert gas (usually helium) before and duringanalysis. Some x-ray spectrometers control the change ofsample chamber atmosphere (air, vacuum, helium) automati-cally through the software; in others, it must be done manua
25、lly.Follow the instrument manufacturers recommendations toachieve the inert gas environment. Allow sufficient stabiliza-tion time before analysis. Fused pellet standards and samplesmay be analyzed using either a vacuum or helium environment.Line intensities will be slightly higher using a vacuum env
26、i-ronment.NOTE 3Caution: Care must be taken to assure that a vacuumenvironment is not chosen with liquid samples. Analyze standards andsamples under the same environment.9.2 X-Ray Power SupplyIf the power to the x-ray tube isnot controlled by the instrument software, set the propercombination of vol
27、tage and current for the instrument in use.These settings must be determined by the user for his instru-ment and choice of x-ray tube. Allow sufficient stabilizationtime prior to analysis.10. Calibration and Standardization10.1 Internal Standard Solution:10.1.1 Weigh 45 g of the internal standard co
28、mpoundchosen for uranium and5goftheinternal standard compoundchosen for gadolinium into a beaker. Cover with a minimumamount of water. Add concentrated nitric acid slowly.NOTE 4For yttrium oxide and samarium oxide, the reaction will beslow and may require heating. If strontium carbonate is used for
29、uranium,the reaction will be vigorous. The strength of the internal standard solutionmay be changed to achieve optimum excitation with the equipment beingused. The exact concentration of the internal standard solution is notcritical; however, it is critical that the internal standard solution added
30、tostandards and samples be the same.10.1.2 Heat on a hot plate if necessary to complete thedissolution.10.1.3 Cool the solution to room temperature, and transferto a 1000-mL volumetric flask. Filter the solution if necessary.Dilute to volume with water and mix thoroughly.10.2 Calibration Standards:1
31、0.2.1 Liquid Standards:10.2.1.1 Prepare a calibration standard for each concentra-tion level by weighing into a beaker the amounts of uraniumoxide and gadolinium oxide, which have been ignited accord-ing to directions on analysis certificate, given in Table 1.10.2.1.2 Dissolve the oxide in 25 mL of
32、water and 25-mLconcentrated nitric acid. Heat on a hot plate, if necessary tocomplete the dissolution. Reduce volume to 15 mL.10.2.1.3 When cool, transfer each solution to a properlylabeled 25-mL volumetric flask containing the amount ofinternal standard solution indicated in Table 1.NOTE 5The inter
33、nal standard solution may be added using a dispens-ing pipet if desired; however, care must be taken to assure that noadjustment to the dispenser is made between use for standards and use forsamples.10.2.1.4 Dilute to volume with water and mix thoroughly.10.2.2 Pellet Standards:6Reagent Chemicals, A
34、merican Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formul
35、ary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.C 1456210.2.2.1 For each standard, weigh 15 g lithium tetraborateinto a labeled crucible suitable for the fusion technique.NOTE 6Explanation of the fusion technique is beyond the scope ofthis guide. Description of the technique may be fou
36、nd in several soucres(2,3). Platinum, platinum-gold or graphite crucibles have been foundacceptable.10.2.2.2 Add the amounts of uranium oxide and gadoliniumoxide indicated in Table 1.10.2.2.3 Add the amount of internal standard solution (see10.1) indicated in Table 1.NOTE 7The dry-weight equivalent
37、amount of internal standard com-pounds may be weighed directly into each crucible in place of internalstandard solution. If the solution is used with graphite crucibles, pipetteinto the center of the crucible. Do not allow the solution to touch the sidesof crucible.10.2.2.4 Fuse in a muffle furnace
38、set at 10001100C untilall materials are in solution. The pellet will be clear andwithout streaks. Mixing while melting is recommended.NOTE 8Automatic fusers are available and may be substituted, ifdesired. Follow the manufacturers operating instruction. Fusion inplatinum crucibles also may be done o
39、ver an air-gas burner. If the pelletcracks or recrystallizes while cooling, remelting in the same crucible willnot invalidate analysis.10.3 Instrument Calibration:10.3.1 Follow the manufacturers instructions for the instru-ment in use to obtain intensity data for the uranium L-a,gadolinium L-a and t
40、he internal standard lines for eachstandard.10.3.2 Care must be exercised that the analytical conditionsdetermined appropriate for the instrument in use are docu-mented, or recorded, in sufficient detail that these may bereproduced in subsequent runs and when analyzing thesamples.10.3.3 Calculate th
41、e analyte/internal standard ratios fromthe data obtained in 10.3.1. Calculate a calibration curve usingthese ratios. The calibration curve will normally be a straightline of form:Y 5 mX 1 b (1)where:Y 5 concentration of analyte (U or Gd),X 5 analyte/internal standard ratio,m 5 slope of line, andb 5
42、intercept of straight line.11. Procedure11.1 Sample Preparation (Liquid):11.1.1 Mix the powder or grind pellet to ensure homogene-ity. Weigh, to the nearest 0.1 mg, a 1.00-g portion of the sampleinto a beaker or flask. Duplicate aliquots may be required tomeet site or customer quality assurance requ
43、irements.11.1.2 Dissolve in 1+1 (volume/volume) HNO3. Heat on hotplate, if necessary, to achieve complete dissolution.11.1.3 Cool and transfer into a 25-mL volumetric flaskcontaining the internal standard solution.11.1.4 Dilute to volume with water and mix thoroughly.11.2 Sample Preparation (Fusion)
44、:11.2.1 Mix the powder or grind pellet to ensure homogene-ity.11.2.2 Weigh, to the nearest 0.1 mg, a 1.00-g portion of thesample into fusion crucible containing 15 g LiTB. Duplicatealiquots may be required to meet site or customer qualityassurance requirements.11.2.3 Add the internal standard(s) for
45、 the analytes (seeNote 6).11.2.4 Place the crucibles in a muffle furnace set at 1100Cand fuse until all materials are in solution (see Note 7).11.2.5 When cool, label the pellets or place in labeled boxesfor identification.11.3 Counting the Sample:11.3.1 Set the x-ray spectrometer to the conditions
46、noted in10.3.2. If the analytical conditions are controlled by computer,start the computer according to manufacturers instructions forthe software in use.11.3.2 For liquid samples, shake each flask to mix thor-oughly. Fill the liquid sample cup with the recommendedamount of liquid for the instrument
47、 in use.11.3.3 Following manufacturers instrumental instructions,obtain intensities for the analyte and the internal standard lines.11.3.4 Calculate the analyte concentration using the calibra-tion curves generated in 10.3. Weight corrections must beadded if the sample weight is not 1.0000 g.12. Pre
48、cision and Bias12.1 There is no readily available certified material (ura-nium oxide-gadolinium oxide powder/pellet) for this guide;however, control samples of 93 % uranium oxide (U3O8) andgadolinium oxide were prepared by weighing 0.9300 g U3O8and 0.0700 g Gd2O3and dissolving, or fusing, or both, a
49、sdescribed in Section 11. Twelve determinations of uraniumoxide and gadolinium oxide over a three-month period gave anaverage of 93.16 % U3O8and 7.00 % Gd2O3by the fusionprocess with a relative standard deviation of 0.27 % and0.64 %, respectively. The same number prepared as liquid gavean average of 92.98 % U3O8and 6.99 % Gd2O3with a relativestandard deviation of 0.37 % and 0.68 %, respectively.12.2 The t-test for bias showed no statistically significantbias in the data.13. Keywords13.1 gadolinium oxide; uranium oxide; x-ray fluorescence;XRFTABLE 1 Uranium Oxi
