1、Designation: C 1636 06aStandard Guide for theDetermination of Uranium-232 in Uranium Hexafluoride1This standard is issued under the fixed designation C 1636; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. 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 method covers the determination of232U in ura-nium hexafluoride by alpha spectrometry.1.2 This standard does not purport to a
3、ddress 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 to determine theapplicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 787 Spec
4、ification for Uranium Hexafluoride for Enrich-mentC 996 Specification for Uranium Hexafluoride Enriched toLess Than 5 %235UC 1163 Practice for Mounting Actinides for Alpha Spec-trometry Using Neodymium FluorideC 1284 Practice for Electrodeposition of the Actinides forAlpha SpectrometryD 1193 Specifi
5、cation for Reagent WaterD 3084 Practice for Alpha-Particle Spectrometry of WaterD 3648 Practices for the Measurement of Radioactivity2.2 Other StandardsDIN 25711 Determination of the232U isotopic content inuranium containing nuclear fuel solutions by a spectrom-etry.33. Terminology3.1 Definitions:3.
6、1.1 region-of-interest (ROI)the channels, or region, inthe alpha spectra in which the counts due to a specificradioisotope appear on a functioning calibrated alpha spec-trometry system.3.1.2 Reagent blankDI water processed the same as thesamples; used in the determination of the minimum detectableac
7、tivity.4. Summary of Guide4.1 An aliquot of hydrolyzed uranium hexafluoride equiva-lent to 60 micrograms of uranium is converted to a nitric acidsystem and the uranium is extracted onto a solid phaseextraction column. The daughters of uranium decay productsare rinsed from the column and the uranium
8、is then selectivelyeluted. The uranium is reduced and then coprecipitated withneodymium fluoride. Test Method C 1163 provides furtherinformation on the use of neodymium fluoride to prepareactinide mounts for alpha spectrometry. The sample is thencounted by alpha spectrometry, and the232U is calculat
9、edbased on the observed activities of the uranium isotopes in thealpha spectra.4.2 While this guide does not present details on electrodepo-sition as an alternative to neodymium fluoride precipitation forthe preparation of a mount for alpha spectrometry PracticeC 1284 does present details on that op
10、tion.4.3 Alternate separation chemistry approaches may befound in the literature. It is the responsibility of the user of suchalternative separation approaches to validate there effective-ness, especially the removal of potentially interfering thoriumisotopes (section 6.1).5. Significance and Use5.1
11、 The method is applicable to the analysis of materials todemonstrate compliance with the specifications set forth inSpecifications C 787 and C 996.6. Interferences6.1 Incomplete removal of228Th could possibly interferewith the232U determination. Method DIN 25711 addresses thepotential capability for
12、 this method to eliminate this potentialinterference.6.2 Since only the relative amount of232U, relative to totaluranium, is being determined in this method there is no impactto chemical loss in the separation or sample mounting chem-istry. Therefore, unlike most alpha spectrometry methods, noyield
13、tracer is necessary or useful.1This guide is under the jurisdiction of ASTM Committee C26 on Nuclear FuelCycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.Current edition approved July 1, 2006. Published July 2006. Originally approvedin 2006. Last previous edition appr
14、oved in 2006 as C 163606.2For 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.3Deutsches Institut fr Normung e.V.,
15、 Berlin, Germany (www.din.de).1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.3 The alpha emission energies of235U and236U arerelatively close. Thus there is the potential for overlap ofcounts from one isotope into the ROI of the o
16、ther. Where thealpha spectrometry system (section 7.1) provides spectralde-convolution algorithms may be used in the analysis of thespectra. Such de-convolution may allow for minimization ofany possible bias in the reported results. However, it should benoted that these two isotopes typically accoun
17、t for a relativelysmall amount of the overall uranium mass. So any biasbetween the two should result in a relatively small overall biasin the reported232U result.7. Apparatus7.1 Alpha spectrometry system. See practices D 3084 andD 3648 for a description of the apparatus.7.1.1 AROI for each uranium i
18、sotope (232U,234U,235U,236U,and238U) will need to be defined for the alpha spectrometrysystem being used. Based on these defined ROIs the fractionalabundance of alpha decays within the energy range of the ROIfor each isotope (ABiin section 12.1) must be determined.7.2 Ion Exchange Columns, able to h
19、old a 10 mL resin bedand 15 mL solution washes.7.3 Filter Paper, 0.1 m pore size, 25-mm diameter, andcompatible with HF.47.4 Vacuum FunnelPolysulfone twist-lock with stainlesssteel screen for filter mounting.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all t
20、ests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available. Other grades of re-agents may be used, provided it is first ascertained that therea
21、gent is of sufficiently high purity to permit its use withoutlessening the accuracy of the determination.58.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedin Specification D 1193.8.3 Ammonium oxalate (0.1M)Dissolve 14.2 g(NH4)2C2O4
22、H2O in approximately 500 mL water and dilute to1 litre.8.4 EthanolEthyl alcohol, absolute (200 proof), dena-tured.8.5 Hydrochloric acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).8.6 Hydrochloric acid (9M)Add 750 mL concentratedHCl to 100 mL water and dilute to 1 litre.8.7 Hydrochloric acid (
23、1.5M)Add 125 mL concentratedHCl to 500 mL water and dilute to 1 litre.8.8 Hydrochloric acid (1M)Add 83 mL concentrated HClto 500 mL water and dilute to 1 litre.8.9 Hydrofluoric acid (minimum 48 % assay)Concentrated HF, reagent grade.WarningSevere burns can result from exposure of skin toconcentrated
24、 hydrofluoric acid.8.10 Neodymium chloride (10 mg Nd/mL)Heat 25 mL ofconcentrated hydrochloric acid and 1.17 g of neodymium oxideon a hotplate until the neodymium oxide is in solution. Coolthe solution and dilute to 100 mL with water.8.11 Neodymium chloride (100 g Nd/mL)Dilute 1 mL of10 mg Nd/mL sol
25、ution to 100 mL with water.8.12 Neodymium oxide (Nd2O3).8.13 Nitric acid (sp gr 1.42)Concentrated nitric acid(HNO3).8.14 Nitric acid (3M)Add 188 mL concentrated nitricacid to 500 mL water and dilute to 1 litre.8.15 Oxalic acid in 1M HCl (0.1M)Dissolve 12.6 gH2C2O4H2O in 500 mL 1M HCl and dilute to 1
26、 litre with 1MHCl.8.16 20 % Titanium Trichloride (TiCl3) aqueous solutionavailable as a 20 % (w/v) solution of titanium trichloride fromcommercial suppliers.8.17 Extraction Chromatography Resin, containingoctylphenyl-N,N-di-isobutyl carbamoylphosphine oxide(CMPO) dissolved in tri-n-butyl phosphate (
27、TBP) as theimmobilized extractant.69. Hazards9.1 Adequate laboratory facilities, such as fume hoods andcontrolled ventilation, along with safe techniques must be usedin this procedure. Extreme care should be exercised in usinghydrofluoric acid and other hot, concentrated acids. Use ofrubber gloves i
28、s recommended.9.2 Hydrofluoric acid should be used with care by personsfamiliar with its hazards through review of the Material SafetyData Sheet (MSDS) and who are properly equipped to respondto cases of skin contact as suggested in the MSDS.10. Calibration and Standardization10.1 The alpha spectrom
29、etry units should be calibrated forenergy, resolution and efficiency according to the manufactur-ers instructions. The background counting rate for the instru-ment should be measured at a frequency determined by theuser. See Practices D 3084 and D 3648 for additional informa-tion.4Pall Life Sciences
30、 (formerly Gelman) Metricel filter has been found to beacceptable. If you are aware of alternative suppliers, please provide this informationto ASTM International Headquarters. Your comments will receive careful consid-eration at a meeting of the responsible technical committee,1which you may attend
31、.5“Reagent Chemicals, American Chemical Society Specifications,” AmericanChemical Society, Washington, DC.6TRU resin from Eichrom Technologies Inc., Darien IL, USA, has been foundto be acceptable. If you are aware of alternative suppliers, please provide thisinformation to ASTM International Headqua
32、rters. Your comments will receivecareful consideration at a meeting of the responsible technical committee,1whichyou may attend.Horwitz, E. P., Chiarizia, R., Dietz, M. L., Diamond, H., and Nelson, D.,“Separation and Preconcentration of Actinides from Acidic Media by ExtractionChromatography,” Analy
33、tica Chemica Acta, 281, 1993, pp. 361-372.The Eichrom Technologies TRU resin is covered by a patent. Interested partiesare invited to submit information regarding the identification of an alternative(s) tothis patented item toASTM International Headquarters. Your comments will receivecareful conside
34、ration at a meeting of the responsible technical committee, whichyou may attend.C 1636 06a211. Procedure11.1 Pipette an aliquot of hydrolyzed uranium hexafluorideequivalent to 60 g of uranium into a 150 mL beaker.Evaporate to dryness. Dissolve the residue with 10 mL 3MHNO3with gentle heating.11.2 Co
35、ndition a CMPO-TBP column by adding 5 mL 3MHNO3.711.3 Add the sample from Step 11.1 to the CMPO-TBPcolumn and allow it to pass through the column.11.4 Rinse the CMPO-TBP column with 10 mL 3M HNO3.11.5 Rinse the CMPO-TBP column with 5 mL 9M HCl.11.6 Rinse the CMPO-TBP column with 30 mL 1.5M HCl.This
36、may be done with two 15-mL rinses.11.7 Rinse the CMPO-TBP column with 15 mL 0.1MH2C2O4in 1M HCl.11.8 Elute the uranium from the column with 20 mL 0.1M(NH4)2C2O4H2O and collect in a PTFE beaker. If the alterna-tive of electrodeposition (see Practice C 1284) is to be used theeluent may be collected in
37、 a glass beaker instead.11.9 Add 3 drops 20 % TiCl3aqueous solution, 0.75 mL ofthe 100 g Nd/mL solution, and 1 mL concentrated HF to theuranium fraction. Swirl to mix then allow the sample to sit for30 minutes. Standard Method C 1163 should be consulted foradditional information on preparing the neo
38、dymium fluoridemount for alpha spectrometry.11.10 After placement of a 0.1 m, 25-mm diameter filter onthe vacuum funnel rinse first with ethanol and then water.11.11 Add the uranium fraction to the filter and vacuumfilter to dryness. Rinse the filter with water and filter to dryness.Rinse the filter
39、 with ethanol and filter to dryness. Dry the filterunder a heat lamp.11.12 Count the sample for an appropriate counting time ina calibrated alpha spectrometer (see Section 10.1).12. Calculation of Results12.1 Calculation of uranium isotope sample activity:Ai5Gi2 Bi!T 3 E 3 ABi!(1)where:Ai= activity
40、of uranium isotope of interest (Bq) (i=232,234, 235, 236, or 238),Gi= gross counts in the analyte ROI accumulated incount duration T,Bi= background counts in the analyte ROI accumulatedin count duration T,ABi= abundance of alpha decay of uranium isotope ofinterest in defined ROI (section 7.1.1), exp
41、ressed asa fraction,E = detector alpha counting efficiency (cps/dps), andT = counting duration, s.Additional calculations, including reagent blank subtraction,can be found in Practice D 3084.12.2 Calculation of the a priori Minimum Detectable Ac-tivity (MDA) for the uranium isotope of interest8MDAi5
42、4.65 3 Sb1 2.71!E 3 T 3 ABi!(2)where:MDAi= minimum detectable activity (MDA) (Bq) foruranium isotope of interest, andSb= standard deviation of the background counts.12.3 Conversion of activity to mass:Wi5AiSAi(3)where:Wi= weight of uranium isotope of interest (g),SAi= specific activity of uranium is
43、otope (Bq/g),SA232= 792000 Bq/g,9SA234= 231 Bq/g,SA235= 0.07995 Bq/g,SA236= 2.4 Bq/g, andSA238= 0.0124 Bq/g.12.4 Calculation of concentration of232U:C2325W232(Wi3 1000000!(4)where:C232= concentration of232U (g/g U).13. Keywords13.1 Alpha spectrometry; uranium-232; uranium hexafluo-ride; specific act
44、ivity; solid phase extraction; ion exchangecolumn7The 2 mL prepacked TRU column from Eichrom Technologies Inc. has beenfound to be acceptable. If you are aware of alternative suppliers, please provide thisinformation to ASTM International Headquarters. Your comments will receivecareful consideration
45、 at a meeting of the responsible technical committee,1whichyou may attend.8L.A. Curie, “Limits of Qualitative Detection and Quantitative Determination,”Analytical Chemistry, vol. 40, no.3, pp. 586-593, 1968.9Specific activities calculated from data in International Commission onRadiological Protecti
46、on (ICRP) Publication 38, “Radionuclide Transformations:Energy and Intensity of Emissions”, Annals of the ICRP, Vol 11-13, 1983. Alternatespecific activities are acceptable.C 1636 06a3APPENDIXES(Nonmandatory Information)X1. Precision and BiasX1.1 This analytical method does not have sufficient data
47、tobe qualified as a Standard Method for ASTM but is offered asa Guide for those wishing options for the analysis of232Uinuranium hexafluoride. At present there are no Certified Refer-ence Materials available from a national standards body toprovide a complete Precision and Bias statement, however th
48、einformation below is offered as an example of data producedfollowing this Guide.X1.2 Twenty samples of uranium hexafluoride were spikedat the 0.00125 g232U per gram of uranium level and analyzedto determine precision and bias. The relative standard deviationof the 20 results was 15 % as an indicati
49、on of precision. Thepercent recovery was 103 % as an indication of bias.X2. Alpha Emission Energies and AbundancesX2.1 See Table X2.1.X3. SensitivityX3.1 Specifications C 787 and C 996 have limits for232Uas low as 0.0001 g/g U. Based on the parameters presented inTable X3.1 a232U concentration of 0.00006 g/g U can bedetermined using the method presented in this guide.TABLE X2.1 Emission energy and abundance of major alphaemissions of select isotopesAUranium isotope Energy, keV Abundance, %232U 5139.0 6 2.0 0.30 6 0.025263.36 6 0.09 31.55 6
