1、Designation: C 1000 05Standard Test Method forRadiochemical Determination of Uranium Isotopes in Soil byAlpha Spectrometry1This standard is issued under the fixed designation C 1000; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、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 test method covers the determination of alpha-emitting uranium isotopes in soil. This test method de
3、scribesone acceptable approach to the determination of uraniumisotopes in soil.21.2 The test method is designed to analyze 10 g of soil;however, the sample size may be varied to 50 g depending onthe activity level. This test method may not be able tocompletely dissolve all forms of uranium in the so
4、il matrix.Studies have indicated that the use of hydrofluoric acid todissolve soil has resulted in lower values than results usingtotal dissolution by fusion.1.3 The lower limit of detection is dependent on count time,sample size, detector efficiency, background, and tracer yield.The chemical recove
5、ry averaged 78 % in a single laboratoryevaluation, and 66 % in an interlaboratory collaborative study.1.4 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 he
6、alth practices and determine the applica-bility of regulatory limitations prior to use. A specific precau-tionary statement is given in Section 10.2. Referenced Documents2.1 ASTM Standards:3C 998 Practice for Sampling Surface Soil for RadionuclidesC 999 Practice for Soil Sample Preparation for the D
7、eter-mination of RadionuclidesC 1163 Test Method for Mounting Actinides for AlphaSpectrometry Using Neodymium FluorideC 1284 Practice for Electrodeposition of the Actinides forAlpha SpectrometryD 1193 Specification for Reagent WaterD 3084 Practice for Alpha-Particle Spectrometry of WaterD 3648 Pract
8、ices for the Measurement of Radioactivity3. Summary of Test Method3.1 A soil sample with uranium-232 tracer added is heatedto destroy organic matter and dissolved with a mixture ofhydrofluoric acid and nitric acid. The uranium is coprecipitatedwith ferric hydroxide and the precipitate is dissolved w
9、ithhydrochloric acid. Iron is removed by extraction with isopropylether, and plutonium, radium, and thorium are separated fromuranium by anion exchange. Uranium is electrodeposited on astainless steel disk and determined by alpha spectrometry. Asan option, the uranium may be prepared for alpha spect
10、romet-ric measurement by using coprecipitation with neodymiumfluoride.4. Significance and Use4.1 This test method is used to analyze soil for alpha-emitting uranium isotopes. It can be used to establish baselineuranium levels and to monitor depositions from nuclear facili-ties.5. Interferences5.1 Pr
11、otactinium-231 may not be completely separated bythe procedure and could interfere with the determination ofuranium-233 or uranium-234 because it has the followingalpha energies in MeV: 5.06, 5.03, 5.01, 4.95 and 4.73 (seeAppendix X1). If neptunium is present in the sample in the plusfour oxidation
12、state, it will co-elute with the uranium.5.2 Since uranium-232 is added as a tracer, it can not bedetermined in soil. Uranium-232 is rarely present in soilsamples. If present in significant quantities relative to the1This test method is under the jurisdiction of ASTM Committee C26 on NuclearFuel Cyc
13、le and is the direct responsibility of Subcommittee C26.05 on TestMethods.Current edition approved June 1, 2005. Published July 2005. Originally approvedin 1983. Last previous edition approved in 2000 as C 1000 00.2Casella, V. A., Bishop, C. T., and Glosby, A. A., “Radiometric Method for theDetermin
14、ation of Uranium in Soil and Air,” U.S. Environmental Protection Agency,EPA-600/7-80-019, Las Vegas, NV, February 1980; and in Practices D 3084 andD 3648.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMS
15、tandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.activity of uranium-232 tracer added, uranium-232 will lead toan overestimation of the chemi
16、cal yield and a low bias inuranium results.6. Apparatus6.1 Alpha Pulse Height Analysis System:26.1.1 A system consisting of a charged particle detectorcapable of 50 keV or less resolution on samples electrodepos-ited on a flat mirror-finished stainless steel disk is required.6.1.2 The resolution is
17、defined as the width of an alpha peakwhen the counts on either side of the peak are equal to one-halfof the counts at the maximum of the peak (full width at halfmaximum height (FWHM).6.1.3 The counting efficiency of the system should begreater than 15 % and the background in the energy region ofeach
18、 peak should be less than 0.010 cpm.6.1.4 A regular program of measurement control operationsshould be conducted for the alpha spectrometry system such asregular background checks, daily source check to determinesystem stability, control charting, and careful handling ofsamples during changing.6.2 B
19、eakers and Covers (TFE-fluorocarbon), 250 mL.6.3 Porcelain Crucible,60mL.6.4 Centrifuge and Bottles, 250-mL capacity.6.5 Ion Exchange Columns, 1.3 cm inside diameter by 15cm long with 100 mL reservoir.6.6 Automatic Pipettes, 0.1 to 1.0 mL with disposable tips.6.7 Furnace, able to maintain 600C.7. Re
20、agents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society, wheresuch specifications are available.4Other grades may b
21、e used,provided 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 WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedin Specification D 1193, T
22、ype I.7.3 Reagent purity shall be such that the measured radioac-tivity of blank samples does not exceed the calculated probableerror of measurement.7.4 Ammonium Hydroxide (0.15 M)Mix 10 mL of con-centrated ammonium hydroxide with water and dilute to 1 L.7.5 Ammonium Hydroxide (sp gr 0.90)Concentrat
23、ed am-monium hydroxide (NH4OH). Keep tightly capped to mini-mize the uptake of carbon dioxide.7.6 Ammonium Sulfate Solution (1 M)Dissolve 132 g of(NH4)2SO4in water and dilute to 1 L.7.7 Anion Exchange Resin5Type 1 anion exchange resin,8% cross-linked, 100-200 mesh, chloride form. Prepare a resinslur
24、ry by soaking the resin in 8M HCl and transfer the slurry toan ion exchange column so that the resin column is approxi-mately 10 cm high.7.8 Ferric Chloride Solution (0.18 M in 0.5 M HCl)Dissolve 48 g of FeCl3.6H2Oin0.5M HCl and dilute to 1 L.7.9 Hydriodic Acid (48 %)Concentrated hydriodic acid(HI).
25、7.10 Hydrochloric Acid (0.5 M)Mix 42 mL of concen-trated HCl with water and dilute to 1 L.7.11 Hydrochloric Acid (1 M)Mix 83 mL of concentratedHCl with water and dilute to 1 L.7.12 Hydrochloric Acid (6 M)Mix 500 mL of concen-trated HCl with water and dilute to 1 L.7.13 Hydrochloric Acid (8 M)Mix 667
26、 mL of concen-trated HCl with water and dilute to 1 L.7.14 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).7.15 Hydrochloric Acid-Hydriodic Acid Solution (HCl-HI)Mix 1 mL of concentrated HI with 50 mL of 6 M HCl.Prepare immediately before use.7.16 Hydrofluoric Acid (48 %)Concentr
27、ated hydrofluoricacid (HF).7.17 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).7.18 Uranium-232, Standard Solution.67.19 Boric AcidSolid.7.20 Isopropyl Ether.8. Sampling8.1 Collect the sample in accordance with Practice C 998.8.2 Prepare the sample for analysis in accordance withPractice C 9
28、99.9. Calibration and Standardization9.1 If a standard uranium-232 solution is not available foruse as a tracer, standardize a freshly prepared sample ofuranium-232; for guidance refer to Practices D 3648. Thisstandard may also be used to establish the counting efficiencyof the alpha spectrometer wh
29、ich then can be used to calculatethe chemical recovery and lower limit of detection (LLD) ofthe test method.10. Precautions10.1 Adequate laboratory facilities, such as fume hoods andcontrolled ventilation, along with safe techniques, must be usedin this procedure. Extreme care should be exercised in
30、 usinghydrofluoric and other hot, concentrated acids. Use of propergloves is recommended. Refer to the laboratorys chemicalhygiene plan and other applicable guidance for handlingchemical and radioactive materials and for the management ofradioactive, mixed, and hazardous waste.4“Reagent Chemicals, A
31、merican Chemical Society Specifications,” Am. Chemi-cal Soc., Washington, DC. For suggestions on the testing of reagents not listed bytheAmerican Chemical Society, see “Reagent Chemicals and Standards,” by JosephRosin, D. Van Nostrand Co., Inc., New York, NY, and the “United StatesPharmacopeia.”5Ag1
32、-X8 from BioRad Laboratories (Hercules, CA) and A8-B500-M-Cl fromEichrom Technoloigies, Inc.(Darien, IL) have been found to be satisifactory.6Uranium-232 is available from the National Institute of Standards andTechnology, Gaithersburg, MD 20899, as a Standard Reference Material.C100005210.2 Hydrofl
33、uoric acid is a highly corrosive acid that canseverly burn skin, eyes, and mucous membranes. Hydrofluoricacid is similar to other acids in that the initial extent of a burndepends on the concentration, the temperature, and the durationof contact with the acid. Hyrdofluoric acid differs from otheraci
34、ds because the fluoride ion readily penetrates the skin,causing destruction of deep tissue layers. Unlike other acidsthat are rapidly neutralized, hydrofluoric acid reactions withtissue may continue for days if left untreated. Due to theserious consequences of hydrofluoric acid burns, prevention ofe
35、xposure or injury of personnel is the primary goal. Utilizationof appropriate laboratory controls (hoods) and wearing ad-equate personal protective equipment to protect from skin andeye contact is essential.11. Procedure11.1 Acid Dissolution:11.1.1 Weigh a 10 6 0.01 g soil sample into a porcelaincru
36、cible.11.1.2 Add an appropriate amount of uranium-232 tracer tothe sample. (If the activity of the sample is expected to be lessthan 0.01 Bq/g or is unknown, add 0.1 Bq of tracer. For higherlevels add uranium-232 tracer which is equivalent to theestimated activity of uranium in the sample.)11.1.3 He
37、at the porcelain crucible containing the soilsample in a muffle furnace at 600C for 4 h, remove, and cool.11.1.4 Transfer the sample to a 250-mL TFE-fluorocarbonbeaker and rinse the porcelain crucible several times withconcentrated HNO3until the final volume is 60 mL.11.1.5 Add 30 mL of 48 % HF to t
38、he beaker and cover witha TFE-fluorocarbon watchglass. Heat the sample for one hourand stir frequently with a TFE-fluorocarbon stirring rod duringthe heating. Cool the solution.11.1.6 Add 30 mL each of concentrated HNO3and 48 % HFand digest with some stirring for an additional hour.11.1.7 Add 20 mL
39、of concentrated HCl and heat. Occasion-ally stir the solution.11.1.8 Remove the cover and evaporate the solution toapproximately 20 mL. Cool the solution.11.1.9 Add 50 mL of water and boric acid to the solutionand heat while stirring for 10 min to dissolve the soluble salts.11.1.10 Cool and transfer
40、 the sample solution to a 250-mLcentrifuge bottle and wash the beaker with a minimum amountof water and combine.11.1.11 Centrifuge and transfer the supernate to a 250-mLcentrifuge bottle. Wash the residue with 10 mL of 1 M HCl andadd the washing to the supernate.11.1.12 Wash the residue with 10 mL o
41、f 1 M HCl, centri-fuge, and add the washing to the supernate.11.2 Co-Precipitation:11.2.1 Add 2 mL of 0.18 M ferric chloride solution to thesupernate in the centrifuge bottle and stir. It may not benecessary to add the iron carrier if a sufficient amount of ironis present in the soil.11.2.2 Add conc
42、entrated NH4OH to the sample solutionwhile mixing to precipitate the iron and until the pH reaches 9to 10.11.2.3 Add 5 mL of concentrated NH4OH in excess.11.2.4 Centrifuge the sample for 5 min, discard the super-nate. Dissolve the precipitate with a minimum addition ofconcentrated HCl and bring the
43、volume to 50 mL with 8 MHCl.11.2.5 Transfer the sample to a 250-mL separatory funneland rinse the centrifuge bottle with two 5 mL rinses of 8 MHCl.11.3 Ether Extraction:11.3.1 Add 60 mL of isopropyl ether to the funnel, stopper,and shake for 2 min.Allow the phases to separate and drain theaqueous ph
44、ase into a second separatory funnel.11.3.2 Add 5 mL of concentrated HCl to the second funneland mix. Add 60 mL of isopropyl ether and repeat theextraction twice more to remove iron. (Additional extractionsmay be necessary if the third extract is yellow, indicatingincomplete removal of the iron).11.3
45、.3 Transfer the aqueous phase to a 150-mL beaker andboil the solution for 15 min.11.4 Anion Exchange Separation:11.4.1 Condition the anion exchange column (7.7) by rins-ing with four column volumes of 8 M HCl.11.4.2 Transfer the sample to the anion exchange columnand pass the sample through the colu
46、mn at a rate of 2 mL permin.11.4.3 Wash the column with six column volumes of 6 MHCl containing 1 mL of concentrated HI per 50 mL of 6 MHCl, prepared immediately before use, to remove iron andplutonium.11.4.4 Wash the column with two column volumes of 6 MHCl.11.4.5 Elute the uranium with six column
47、volumes of 1 MHCl and collect in a 150-mL beaker.11.4.6 Evaporate the sample to 20 mL and add 5 mL ofconcentrated HNO3. Evaporate the sample to near dryness.11.5 Electrodeposition:11.5.1 Uranium can also be prepared for alpha spectrometryby coprecipitation with neodymium fluoride, see Test MethodC 1
48、163 or by electrodeposition using Practice C 1284.11.5.2 Count the sample on a calibrated alpha pulse heightanalyses system within 1 week or sooner to prevent interfer-ences from uranium-232 daughters.11.6 Alpha Pulse Height Analysis:11.6.1 Count the sample on an alpha spectrometer for 1,000min or l
49、onger to resolve the uranium isotopes.211.6.2 Determine the background and reagent blank activi-ties and correct the count for each peak.12. Calculation12.1 The activity of each uranium isotope is calculated asfollows:C1000053Xi5 CiAt!/CtWs! (1)where:Xi= concentration of a uranium isotope in Bq/g,At= activity of the internal standard added in Bq,Ci= net sample counts in the energy region of the uraniumisotope being measured,Ct= net sample counts in the energy region of theuranium-232 tracer, andWs= the sample weight in g.12.2 The absolute counting efficiency of
