1、Designation: D 3972 02Standard Test Method forIsotopic Uranium in Water by Radiochemistry1This standard is issued under the fixed designation D 3972; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er 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 test method covers the determination of alpha-particle-emitting isotopes of uranium in water by means ofchemical separations and alph
3、a 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 present in suspende
4、d 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 validity of this t
5、est method for waters of untested matrices.1.2 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 standard to establish appro-priate safety and health practices and determine the applica-bility of regulato
6、ry limitations prior to use. Specific warningstatements are given in Section 9.2. Referenced Documents2.1 ASTM Standards:C 859 Terminology Relating To Nuclear Materials2D 1066 Practice for Sampling Steam3D 1129 Terminologies Relating to Water3D 1192 Guide for Equipment for Samping Water and Steamin
7、Closed Conduits3D 1193 Specification for Reagent Water3D 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D19 on Water3D 3084 Practice for Alpha-Particle Spectrometry of Water4D 3370 Practices for Sampling Water3D 3648 Practices for the Measurement of Radioacti
8、vity4D 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis43. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method, referto Terminologies C 859 and D 1129. For terms not included inthese reference may be made to other pub
9、lished glossaries.5,64. Summary of Test Method4.1 The water sample to be analyzed is acidified and232Uis added to serve as an isotopic tracer before any additionaloperations are performed. If the sample is a seawater sample,or if it contains carbonate or bicarbonate ions, the sample mustbe boiled un
10、der 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 is coprecipitated from the samplewith ferrous hydroxi
11、de. 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 from other radionuclides byadsorption on anion-exchange
12、 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-heightanalysis with a silicon surface-barrier or ion-implanted detectorand a multichannel analyz
13、er.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 alpha energiesgiven in the table, it can be seen that the alpha energy of232Uis more than 0.40 MeV higher than the energy of any otherura
14、nium isotope. Thus, there should be little interference fromtailing of the232U into the lower energy alpha peaks.233U and234U usually cannot be resolved because their principal alphaenergies differ by only 0.04 MeV.235U and236U peaks can beresolved only with difficulty. The alpha peaks from othercom
15、binations of uranium isotopes can be resolved unless thequality of the finally prepared sample is poor.1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemi-cal Analysis.Current edition approved Feb.
16、 10, 2002. Published May 2002. Originallypublished as D 3972 80. Last previous edition D 3972 97.2Annual Book of ASTM Standards, Vol 12.01.3Annual Book of ASTM Standards, Vol 11.01.4Annual Book of ASTM Standards, Vol 11.02.5Parker, S. P., ed., McGraw-Hill Dictionary of Chemical Terms, McGraw-HillBoo
17、k Co., New York, NY, 1985.6IUPAC, “Glossary of Terms Used in Nuclear Analytical Chemistry,” Pure andApplied Chemistry, Vol 54, 1982, pp. 15331554.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Significance and Use5.1 This test me
18、thod was developed to measure 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, pluton
19、ium, and americium werefound not to interfere in this uranium determination.7The onlypossible alpha-emitting isotope that might interfere, based onthe chemistry of this test method, is231Pa (3.28 3 104yhalf-life). This isotope, however, is not likely to be present inenvironmental water samples.231Pa
20、 has the following alphaenergies in MeV, the abundance being given in parentheses:5.013 (25.4 %), 5.03 (23 %), 4.951 (22.5 %), 5.059 (11 %), and4.734 (8.4 %). Thus, from Table 1, it is seen that231Pa caninterfere with the determination of233Uor234U. However,when the 4.951 to 5.059 MeV231Pa peaks can
21、 be resolvedfrom the uranium peaks, a correction can be made.6.2 When measuring very low concentrations of uraniumisotopes in environmental samples, detector backgrounds andlaboratory blanks must be well known. Blank determinationsare made to ascertain that any contamination from reagents,glassware
22、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 Centrifuge, 250-mL centrifuge bottle or tube capacity.7.2 Ion Exchange Column, glass or plastic
23、, 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 constant current) and anelectrodeposition cell. The cathode is an approximately 20-mmdiam
24、eter 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 the electrolyte duringelectrodeposition to at least 50C is recommended. See refer-ences
25、in Section 8 of Practice D 3084 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 capable ofgiving a resolution of 30 keV FWHM or better, when measuredwith a high-quali
26、ty 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 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwis
27、e indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society.8Other grades may be used provided it is first ascertained thatthe reagent is of sufficiently high purity to permit its usewithout reducing the pre
28、cision, or increasing the bias, of thedetermination.8.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Specifications D 1193, Type III, as a minimum.8.3 Radioactive Purity of ReagentRadioactive purity shallbe such that the measured
29、 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 of concentrated NH4OH (sp gr 0.90) with 99 v
30、olumesof 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 concentrated NH4OH orconcentrated H2SO4while stir
31、ring 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.7Bishop, C. T., Casella, V. R., and Glosby, A. A., “Radiometric Method for
32、 theDetermination of Uranium in Water: Single-Laboratory Evaluation and Interlabo-ratory Collaborative Study,” U.S. Environmental Protection Agency Report,EPA600/7-79-093, April 1979.8Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestio
33、ns 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 Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.TABLE 1 Relevant Properties of Ur
34、anium Isotopes of Interest inEnvironmental WatersAIsotopeHalf Life Principal Alpha Energies in MeVYears (Abundance)232U 68.9 5.320(68.6)5.262(31.4)233U 1.592 3 1054.824(83.3)4.782(14.1)234U 2.455 3 1054.774(72.5)4.722(27.5)235U 7.038 3 1084.596(5.6)4.307 (57)4.366 (17)4.214(6.4)236U 2.342 3 1074.493
35、 (74)4.445 (26)238U 4.468 3 1094.198 (77)4.151 (23)ATable of Isotopes, Eighth Edition, Vol. 11, Richard B. Firestone, LawrenceBerkeley National Laboratory, University of California, 1996.D39720228.9 Ferric Chloride Carrier Solution (20 mg Fe/mL)Dissolve 9.6 g of FeCl36H2O in 100 mL of 0.5 M HCl.8.10
36、 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. Thissolution is 8 M.8.13 Hydrochloric Acid 0.5 M (1+23)Mix 1 volume ofconcentrated HC
37、l (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 hydrof-luoric acid (HF).8.16 Hydroiodic Acid (sp gr 1.5)Concentrated hydroiodicacid
38、(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 mL of concentrated H2SO4(sp gr 1.84) whilestirring. This solution contains about5gofNaHSO4per 100mL of 9 M H2
39、SO4.8.19 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 9volumes of water. This solution is 1.8 M.8.22 Thymol Blue Indicator SolutionD
40、issolve 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. Wear rubber gloves, safetyglasses or goggles, and a laboratory coat. Avoid
41、breathing anyHF fumes. Clean up all spills promptly and wash thoroughlyafter using HF.10. Sampling10.1 Collect the sample in accordance with Practices D1066 and D 3370 and Specification D 1192 as applicable.Preserve the sample by adjusting the pH to 1 with concentratedHCl if the sample is not to be
42、analyzed within 24 h. Record thevolume of the sample and the volume of acid added.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
43、 separation. See Practices D 3084 and D 3648 forgeneral guidance concerning the standardization 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
44、. Procedure12.1 Coprecipitation:12.1.1 Measure the volume of approximately 1 L of thewater 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 sample com-pletely, and check the acidity
45、 with pH-indicating paper or strip.If the pH is greater than 1, add concentrated HCl with mixinguntil 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
46、 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 b
47、oiling for 10 min.12.1.8 Without removing the watch glass, add concentratedNH4OH from a polyethylene squeeze bottle with the deliverytube inserted under the watch glass at the beaker pouring lip.Continue adding concentrated NH4OH until a light permanentturbidity is produced, and then add an excess o
48、f 10 mL. Boilthe solution for an additional 10 min.12.1.9 Add another 1 mL of concentrated NH4OH andcontinue to stir the sample for 30 min without heating.12.1.10 Allow the sample to settle (approximately 30 min)and decant the supernate, being careful not to remove anyprecipitate.12.1.11 Slurry the
49、remaining precipitate and supernate, andtransfer to a centrifuge bottle or tube.12.1.12 Centrifuge the sample and pour off the remainingsupernate. Discard the supernates to waste.12.1.13 Attempt to dissolve the precipitate with a minimumvolume of concentrated HCl. If the precipitate dissolvescompletely, add a volume of concentrated HCl equal to twicethe volume of the sample solution and dilute to 100 to 150 mLwith 8 M HCl (2+1), or otherwise adjust the acidity to 8 M HCl,and then proceed to 12.3. If the precipitate does not dissolve inHCl, evaporate to dryness
