1、Designation: D3972 09 (Reapproved 2015)Standard Test Method forIsotopic Uranium in Water by Radiochemistry1This standard is issued under the fixed designation D3972; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、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 test method covers the determination of alpha-particle-emitting isotopes of uranium in water by means ofchemical separ
3、ations and alpha pulse-height analysis (alsoknown as alpha-particle spectrometry). Uranium is chemicallyseparated from a water sample by coprecipitation with ferroushydroxide, anion exchange, and electrodeposition. The testmethod applies to soluble uranium as well as to any uraniumthat might be pres
4、ent in suspended matter in the water sample.This test method is applicable for uranium processing effluentsas well as substitute ocean water. When suspended matter ispresent, an acid dissolution step is added to assure that all ofthe uranium dissolves. It is the users responsibility to ensurethe val
5、idity of this test method for waters of untested matrices.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theres
6、ponsibility 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. Specific warningstatements are given in Section 9.2. Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclear Ma
7、terialsC1163 Practice for MountingActinides forAlpha Spectrom-etry Using Neodymium FluorideD1066 Practice for Sampling SteamD1129 Terminology Relating to WaterD1192 Guide for Equipment for Sampling Water and Steamin Closed Conduits (Withdrawn 2003)3D1193 Specification for Reagent WaterD2777 Practice
8、 for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3084 Practice for Alpha-Particle Spectrometry of WaterD3370 Practices for Sampling Water from Closed ConduitsD3648 Practices for the Measurement of RadioactivityD5847 Practice for Writing Quality Control Spe
9、cificationsfor Standard Test Methods for Water AnalysisD7282 Practice for Set-up, Calibration, and Quality Controlof Instruments Used for Radioactivity Measurements3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method, referto Terminologies C859 and D1129. For terms n
10、ot included inthese reference may be made to other published glossaries.4,54. Summary of Test Method4.1 The water sample to be analyzed is acidified and232Uisadded to serve as an isotopic tracer before any additionaloperations are performed. If the sample is a seawater sample,or if it contains carbo
11、nate or bicarbonate ions, the sample mustbe boiled under acidic conditions to convert these ions tocarbon dioxide gas which is then expelled from the solution.Carbonate ions must not be present during the precipitationstep because they complex the uranium and prevent itscoprecipitation. The uranium
12、is coprecipitated from the samplewith ferrous hydroxide. This precipitate is dissolved in con-centrated hydrochloric acid, or is subjected to an acid dissolu-tion with concentrated nitric and hydrofluoric acids if thehydrochloric acid fails to dissolve the precipitate.4.2 The uranium is separated fr
13、om other radionuclides byadsorption on anion-exchange resin from 8 M hydrochloricacid, followed by elution with 0.1 M hydrochloric acid. Theuranium is electrodeposited onto a stainless steel disk. Isotopicuranium radioactivities are measured by alpha pulse-height1This test method is under the jurisd
14、iction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemi-cal Analysis.Current edition approved Jan. 1, 2015. Published January 2015. Originallyapproved in 1980. Last previous edition approved in 2009 as D3972 09. DOI:10.1520/D3972-09R15.2F
15、or 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.3The last approved version of this historical standard is refer
16、enced onwww.astm.org.4Parker, S. P., ed., Dictionary of Chemical Terms, McGraw-Hill Book Co., NewYork, NY, 1985.5IUPAC, “Glossary of Terms Used in Nuclear Analytical Chemistry,” Pure andApplied Chemistry, Vol 54, 1982, pp. 15331554.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, We
17、st Conshohocken, PA 19428-2959. United States1analysis with a silicon surface-barrier or ion-implanted detectorand a multichannel analyzer.4.3 When232U is used as the tracer, the other isotopes ofuranium listed in Table 1 can be detected in the alpha-particlespectrum of an unknown sample. From the a
18、lpha energiesgiven in the table, it can be seen that the alpha energy of232Uis more than 0.40 MeV higher than the energy of any otheruranium isotope. Thus, there should be little interference fromtailing of the232U into the lower energy alpha peaks.233Uand234U usually cannot be resolved because thei
19、r principalalpha energies differ by only 0.04 MeV.235U and236U peakscan be resolved only with difficulty. The alpha peaks fromother combinations of uranium isotopes can be resolved unlessthe quality of the finally prepared sample is poor.5. Significance and Use5.1 This test method was developed to m
20、easure the radio-activity of uranium isotopes in environmental waters or watersreleased to the environment, and to determine whether theuranium-isotope concentrations are below the maximumamounts allowable by any regulatory statute.6. Interferences6.1 Thorium, polonium, plutonium, and americium were
21、found not to interfere in this uranium determination.6The onlypossible alpha-emitting isotopes that might interfere, based onthe chemistry of this test method, are231Pa (3.28 104yhalf-life) and237Np (2.16 106y half-life). These isotopes,however, are not likely to be present in environmental watersam
22、ples. Protactinum-231 has the following alpha energies inMeV, the abundance being given in parentheses: 5.013(25.4 %), 5.03 (23 %), 4.951 (22.5 %), 5.059 (11 %), and 4.734(8.4 %). Thus, from Table 1, it is seen that231Pa can interferewith the determination of233Uor234U. However, when the4.951 to 5.0
23、59 MeV231Pa peaks can be resolved from theuranium peaks, a correction can be made. Neptunium-237 hasalpha emission energies ranging from 4.639 to 4.873 MeV,with 72 % found between 4.771 and 4.788 MeV. Conventionalanalytical equipment would not be able to resolve these peaksfrom normal234U emissions.
24、 If Np-237 is suspected to bepresent in the sample, a separate237Np analysis would berequired to make the appropriate correction to the234U result.6.2 When measuring very low concentrations of uraniumisotopes in environmental samples, detector backgrounds andlaboratory blanks must be well known. Bla
25、nk determinationsare made to ascertain that any contamination from reagents,glassware and other laboratory apparatus is small compared tothe activity in the sample that is being analyzed. A blankdetermination should be made in exactly the same way as thesample determination.7. Apparatus7.1 Centrifug
26、e, 250-mL centrifuge bottle or tube capacity.7.2 Ion Exchange Column, glass or plastic, approximately13-mm inside diameter and 150 mm long with a glass-woolplug or plastic frit and a 100- to 150-mL reservoir.7.3 Electrodeposition Apparatus, consisting ofa0to12-V,0 to 2-A power supply (preferably con
27、stant current) and anelectrodeposition cell. The cathode is an approximately 20-mmdiameter stainless steel disk polished to a mirror finish. Theanode is approximately 1-mm diameter platinum wire with anapproximately 8-mm diameter loop at the end of the wireparallel to the cathode disk. Cooling of th
28、e electrolyte duringelectrodeposition to at least 50C is recommended. See refer-ences in Section 8 of Practice D3084 for more details.7.4 Alpha Pulse-Height Analysis System, consisting of asilicon surface-barrier or ion-implanted detector, supportingelectronics, and pulse-height analyzer. A system c
29、apable ofgiving a resolution of 30 keV FWHM or better, when measuredwith a high-quality source, is recommended. The countingefficiency of the system should be greater than 15 %, and thebackground in the energy region of each peak should be lessthan ten counts in 60 000 s.8. Reagents and Materials8.1
30、 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society.7Other grades may be used provided it is first ascertained tha
31、t6Bishop, C. T., Casella, V. R., and Glosby, A. A., “Radiometric Method for theDetermination of Uranium in Water: Single-Laboratory Evaluation and Interlabo-ratory Collaborative Study,” U.S. Environmental Protection Agency Report,EPA600/7-79-093, April 1979.7Reagent Chemicals, American Chemical Soci
32、ety Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopei
33、al Convention, Inc. (USPC), Rockville,MD.TABLE 1 Relevant Properties of Uranium Isotopes of Interest inEnvironmental WatersAIsotopeHalf Life Principal Alpha Energies in MeVYears (Abundance)232U 68.9 5.320(68.6)5.262(31.4)233U 1.5921054.824(83.3)4.782(14.1)234U 2.4551054.774(72.5)4.722(27.5)235U 7.03
34、81084.596(5.6)4.307 (57)4.366 (17)4.214(6.4)236U 2.3421074.493 (74)4.445 (26)238U 4.4681094.198 (77)4.151 (23)ATable of Isotopes, Eighth Edition, Vol. 11, Richard B. Firestone, LawrenceBerkeley National Laboratory, University of California, 1996.D3972 09 (2015)2the reagent is of sufficiently high pu
35、rity to permit its usewithout reducing the precision, or increasing the bias, of thedetermination.8.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Specifications D1193, Type III, as a minimum.8.3 Radioactive Purity of ReagentRadi
36、oactive purity shallbe such that the measured results of blank samples do notexceed the calculated probable error of the measurement or arewithin the desired precision.8.4 Ammonium Hydroxide (sp gr 0.90)Concentrated am-monium hydroxide (NH4OH).8.5 Ammonium Hydroxide Solution 0.15 M (1+99)Mix 1volume
37、 of concentrated NH4OH (sp gr 0.90) with 99 volumesof water. This solution is 0.15 M.8.6 Anion-Exchange ResinStrongly basic, styrene, quater-nary ammonium salt, 4 % crosslinked, 100 to 200 mesh,chloride form.8.7 ElectrolyteDissolve 132 g of ammonium sulfate inwater and dilute to 1 L. Slowly add conc
38、entrated NH4OH orconcentrated H2SO4while stirring to adjust the pH of thesolution to 3.5. The solution is 1 M in (NH4)2SO4.8.8 Ethyl Alcohol (C2H5OH)Make slightly basic with afew drops of concentrated NH4OH per 100 mL of alcohol.Anhydrous denatured ethanol is acceptable.8.9 Ferric Chloride Carrier S
39、olution (20 mg Fe/mL)Dissolve 9.6 g of FeCl36H2O in 100 mL of 0.5 M HCl.8.10 Filter paper, ashless, medium porosity.8.11 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).8.12 Hydrochloric Acid 8 M (2+1)Mix 2 volumes ofconcentrated HCl (sp gr 1.19) with 1 volume of water. Thissolut
40、ion is 8 M.8.13 Hydrochloric Acid 0.5 M (1+23)Mix 1 volume ofconcentrated HCl (sp gr 1.19) with 23 volumes of water.8.14 Hydrochloric Acid 0.1 M (1+119)Mix 1 volume ofconcentrated HCl (sp gr 1.19) with 99 volumes of water. Thissolution is 0.1 M.8.15 Hydrofluoric Acid (sp gr 1.2)Concentrated hydroflu
41、-oric acid (HF).8.16 Hydroiodic Acid (sp gr 1.5)Concentrated hydroiodicacid (HI).8.17 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).8.18 Sodium Hydrogen SulfateSulfuric AcidDissolve 10g of sodium hydrogen sulfate in 100 mL of water and thencarefully add 100 mLof concentrated H2SO4(sp gr 1.8
42、4) whilestirring. This solution contains about5gofNaHSO4per 100mL of 9 M H2SO4.8.19 Sodium Hydrogen Sulfite (NaHSO3).8.20 Sulfuric Acid (sp gr 1.84)Concentrated sulfuric acid(H2SO4).8.21 Sulfuric Acid 1.8 M (1+9)Cautiously add with stir-ring 1 volume of concentrated sulfuric acid (sp gr 1.84) to 9vo
43、lumes of water. This solution is 1.8 M.8.22 Thymol Blue Indicator SolutionDissolve 0.04 g ofthe sodium salt of thymol blue in 100 mL of water.8.23 Uranium-232 Solution, Standard (about 0.2 Bq/mL).9. Precautions9.1 Hydrofluoric acid (HF) is very hazardous and should beused in a well-ventilated hood.
44、Wear rubber gloves, safetyglasses or goggles, and a laboratory coat. Avoid breathing anyHF fumes. Clean up all spills promptly and wash thoroughlyafter using HF. Ready availability of a topical fluoride bindingagent, such as calcium gluconate gel, is strongly recommendedin the event of skin contact
45、with HF.10. Sampling10.1 Collect the sample in accordance with PracticesD1066, D3370, and Specification D1192 as applicable. Pre-serve the sample by adjusting the pH to 1 with concentratedHCl if the sample is not to be analyzed within 24 h. Record thevolume of the sample and the volume of acid added
46、.11. Calibration and Standardization11.1 Standardized232U is required as a tracer. Beforestandardization, this isotope must be separated from its radio-active descendents by anion exchange or some other means ofchemical separation. See Practices D3084 and D3648 forgeneral guidance concerning the sta
47、ndardization of tracers, andthe energy and efficiency calibrations of the detector. Thepulse-height analyzer should be set to accept pulses from alphaparticles of approximately 3.5 to approximately 9.0 MeV inenergy.12. Procedure12.1 Coprecipitation:12.1.1 Measure the volume of approximately 1 L of t
48、hewater sample to be analyzed and transfer to a 2-L beaker.12.1.2 If the sample has not been acidified, add 5 mL ofconcentrated HCl.12.1.3 Add a magnetic stirring bar, mix the samplecompletely, and check the acidity with pH-indicating paper orstrip. If the pH is greater than 1, add concentrated HCl
49、withmixing until it reaches this value.12.1.4 Add approximately 0.2 Bq of standardized232Utracer with a calibrated pipet or by weight.12.1.5 If the sample is a seawater or if it may containcarbonate ions, it must be boiled for approximately 5 min.Check the pH again after boiling and if it is greater than 1, addconcentrated HCl with mixing to bring the pH back to 1.12.1.6 Add approximately 500 mg of NaHSO3and2mLofferric chloride carrier solution.12.1.7 Cover the sample with a watch glass and heat thesample to boiling for 10 min.12.1.8 Without removin
