1、Designation: C 1001 05Standard Test Method forRadiochemical Determination of Plutonium in Soil by AlphaSpectroscopy1This standard is issued under the fixed designation C 1001; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r 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 plutoniumin soils at levels of detection dependent on count time, s
3、amplesize, detector efficiency, background, and tracer yield. This testmethod describes one acceptable approach to the determinationof plutonium in soil.1.2 This test method is designed for 10 g of soil, previouslycollected and treated as described in Practices C 998 andC 999, but sample sizes up to
4、 50 g may be analyzed by this testmethod. This test method may not be able to completelydissolve all forms of plutonium in the soil matrix.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 standard to
5、 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific hazardstatements are given in Section 9.2. Referenced Documents2.1 ASTM Standards:2C 998 Practice for Sampling Surface Soil for RadionuclidesC 999 Practice for Soil S
6、ample Preparation for the Deter-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 Spectr
7、ometry of WaterD 3648 Practice for the Measurement of Radioactivity3. Summary of Test Method3.1 Plutonium is extracted from the soil with a mixture ofnitric, hydrofluoric, and hydrochloric acids in the presence of242Pu or236Pu isotopic tracer (See Appendix for purificationand standardization of236Pu
8、 tracer). Plutonium is isolated byanion exchange, then electrodeposited onto a polished metaldisk for determination by alpha spectrometry.As an option, theplutonium may be prepared for alpha spectrometry measure-ment by using coprecipitation with neodymium fluoride. Therange of chemical yield is bet
9、ween 40 and 90 %. The testmethod is based on a published procedure (1).34. Significance and Use4.1 A soil sampling and analysis program provides a directmeans of determining the concentration and distribution ofradionuclides in soil. A soil analysis program has the mostsignificance for the preoperat
10、ional monitoring program toestablish baseline concentrations prior to the operation of anuclear facility. Soil analysis, although useful in special casesinvolving unexpected releases, is a poor technique for assess-ing small incremental releases and is therefore not recom-mended as a method for rout
11、ine monitoring releases ofradioactive material. Nevertheless, because soil is an integratorand a reservoir of long-lived radionuclides, and serves as anintermediary in several of the plutonium pathways of potentialimportance to humans, knowledge of the concentration ofplutonium in soil is essential.
12、5. Apparatus5.1 Electrodeposition Apparatus (2), see Practice C 1284.5.2 Alpha Spectrometer, capable of 40 to 50 keV resolutionon actual samples electrodeposited on a flat, mirror-finishedmetal planchet, and a counting efficiency greater than 17 %,and a background less than 0.010 cpm over each desig
13、natedenergy region. Resolution is defined as the full width halfmaximum (FWHM) in keV, the distance between those pointson either side of the alpha peak where the count is equal toone-half the maximum count. Also see Practices D 3084 andD 3648.NOTE 1A regular program of measurement control operation
14、s shouldbe conducted for the alpha spectrometry system, such as regular back-ground checks, source check to determine system stability, controlcharting, and careful handling of samples during changing.1This test method is under the jurisdiction of ASTM Committee C26 on NuclearFuel Cycle and is the d
15、irect 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 1001 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service
16、 at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700,
17、 West Conshohocken, PA 19428-2959, United States.5.3 PTFE-polytetrafluoroethylene beakers, 250-mL.6. Reagents6.1 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 on A
18、nalytical Reagents of the American Chemical Society,where such specifications are available (3). Other grades maybe used, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterUnless oth
19、erwise indicated, referencesto water shall be understood to mean reagent water as definedin Specification D 1193, Type III.6.3 Reagent blanks should be run to determine their contri-bution to the sample result.6.4 Ammonium Hydroxide (sp gr 0.90)Concentrated am-monium hydroxide (NH4OH).6.5 Ammonium I
20、odide (NH4I) (1 M)Dissolve 14.5 g ofNH4I in 100 mL water.6.6 Ammonium Iodide, Hydrochloric Acid Solution (NH4I-HCl)Add 25 mL 1 M ammonium iodide to 500 mL concen-trated hydrochloric acid. Prepare fresh prior to use.6.7 Analytical Grade Anion Exchange Resin Type 1, 8 %cross-linked, 100 to 200 mesh, c
21、hloride form4Store the resinin water in a wash bottle, transfer sufficient resin to a 1.3-cm IDion exchange column to give a 10-cm bed of settled resin.Convert the resin to the nitrate form by passing 100 mL ofHNO3(8M) through the column at maximum flow rate.6.8 Boric Acid (H3BO3).6.9 Hydrochloric A
22、cid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).6.10 Hydrochloric Acid (3M)Add 250 mLof concentratedHCl (sp gr 1.19) to 500 mL of water, mix, and dilute to 1.0 Lwith water.6.11 Hydrochloric Acid (1.7M)Add 142 mL of concen-trated HCl (sp gr 1.19) to 500 mL of water, mix, and dilute to1.0 L with
23、 water.6.12 Hydrofluoric Acid (48 to 51 %)Concentrated hydrof-luoric acid (HF).6.13 Iron Carrier solution (10 g Iron (III)/L)Dissolve10.0 g iron metal in HCl (1.7M) and dilute to 1 L with HCl(1.7M).6.14 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).6.15 Nitric Acid (8M)Add 500 mL of concent
24、ratedHNO3(sp gr 1.42) to 400 mL of water, mix, and dilute to 1.0 Lwith water.6.16 Nitric Acid (1.8M)Add 112 mL of concentratedHNO3(sp gr 1.42) to 500 mL of water, mix, and dilute to 1.0 Lwith water.6.17 Octyl alcohol.6.18 Sodium Bisulfite (NaHSO3).6.19 Sodium Hydroxide (50%)Dissolve 500 g of NaOH in
25、500 mL water. A 50% NaOH solution is available commer-cially.6.20 Sodium Nitrite (NaNO2).6.21 Thymol Blue Indicator, Sodium Salt, 0.02 % Solution.6.22 National Standard Traceable Plutonium-236 Reagent.6.23 National Standard Traceable Plutonium-242 Reagent.7. Sampling7.1 Collect the sample in accorda
26、nce with Practice C 998.7.2 Prepare the sample for analysis in accordance withPractice C 999.7.3 Samples consisting of 10 to 50 g of soil can be readilyanalyzed by the procedure. In order to obtain more represen-tative samples, as well as lowering the minimum detectableconcentration, the analyses of
27、 large soil samples is desirable. Ingeneral, it is poor practice to use less than 10 g of sample,unless replicate analyses are performed, because of neededsensitivity to determine lower levels of activity.8. Calibration and Standardization8.1 The counting efficiency of the alpha spectrometer isused
28、to determine the minimum detectable concentration(MDC), lower limit of detection (LLD), and chemical recov-ery. The efficiency of the alpha spectrometer is determined asthe ratio of the observed count rate to the known disintegrationrate times the counting efficiency of the 2p counter. Theprocedure
29、is as follows:8.1.1 Count a241Am source traceable to a national standardsorganization on a 2p alpha counter. The 2p counter efficiencyis determined by:CE2p5 C1/A1!T!1.023! (1)where:C1= net counts of the241Am source,A1= certified activity of the241Am source (cps), cor-rected for decay,T = duration of
30、 the count time, s, and1.023 = backscatter factor correcting the counting effi-ciency of a source on platinum to that on stainlesssteel.8.1.2 Electrodeposit239Pu on a polished metal disk, usingthe equipment and procedure listed in this method, andcounting on the 2p counter. This gives the known disi
31、ntegra-tion rate, C2p.8.1.3 The counting efficiency of the alpha spectrometer isdetermined as follows:CE 5 Cs!CE2p!/C2p! (2)where:Cs= net count rate of the electroplated source over theentire energy region on the alpha spectrometer(cps); the observed count rate,CE2p= counting efficiency of the 2p co
32、unter, andC2p= net counting rate of the same source on the 2pcounter (cps).8.2 The quantity of the tracer to be used should be in theexpected range (but not less than 0.17 Bq) of the isotopicactivity being determined so that the statistical uncertainty in4Resin obtainable from BioRad Laboratories (H
33、ercules, CA) and from EichromTechnologies, Inc. (Darien, IL).C1001052the yield determination will not be larger than that of thenuclide being determined.9. Precautions9.1 Adequate laboratory facilities, such as fume hoods andcontrolled ventilation, along with safe techniques, must be usedin this pro
34、cedure. Extreme care should be exercised in 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,
35、 and hazardous waste.9.2 Hydrofluoric 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. Hydrofl
36、uoric acid differs from otheracids 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 unattended. Due to theserious consequences of hydrof
37、luoric acid burns, prevention ofexposure 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.10. Procedure10.1 Weigh a 10 6 0.01 g soil aliquot into a 25
38、0 mL PTFEbeaker.10.2 Wet sample with distilled water and add a knownquantity of236Pu or242Pu tracer.10.3 Add concentrated HNO3(sp gr 1.42) a few drops at atime as fast as the frothing and vigor of the reaction will permituntil the entire sample is covered.10.4 Add 60 mL of the concentrated HNO3(sp g
39、r 1.42) and30 mL of concentrated HF (48 to 51 %) and digest on ahotplate with frequent stirring (TFE fluorocarbon stirring rod)for about1h(Note 2 and Note 3).NOTE 2For organic soils, first add the nitric acid only in smallportions while stirring. If the solution threatens to overflow as a result off
40、roth generation, add a few drops of octyl alcohol and stir. Digest on ahotplate until the evolution of reddish-brown fumes is reduced to a barelyvisible level. Cool to room temperature before carefully adding theconcentrated hydrofluoric acid (48 to 51 %) and digesting for an hour.NOTE 3For larger s
41、oil aliquots, larger amounts of the acids (in thesame proportions) should be used. For example, for a 50 g sample, use 200mL concentrated. HNO3and 100 mL HF, etc., with appropriately sizedcontainers.10.5 Remove from the hotplate and cool somewhat beforeadding 30 mL concentrated HNO3(sp gr 1.42) and
42、30 mLconcentrated HF (48 to 51 %). Digest on the hotplate withintermittent stirring for an additional 1 h.10.6 Remove from the hotplate and cool. Carefully add 20mL concentrated HCl (sp gr 1.19) and stir. Heat on hotplate for45 min with occasional stirring.10.7 Add about5gofpowdered boric acid and d
43、igest for anadditional 15 min with occasional stirring.10.8 Add approximately 200 mg of sodium bisulfite andcontinue heating until the solution has evaporated to a liquidvolume of approximately 20 mL.10.9 Add 50 mL of water and digest on a hotplate whilestirring for 10 min to dissolve soluble salts.
44、10.10 Cool and transfer approximately equal parts of thetotal sample into centrifuge bottles with a minimum of waterfrom a wash bottle. If equipment for large volume centrifuga-tion is not available, the two precipitations in 10.11-10.21 maybe performed in a beaker, allowing the precipitate to settl
45、e,decanting the supernate, and then completing the separation bycentrifugation on a smaller scale.10.11 Add 1.0 mL of iron carrier solution (10 mg Fe(III)/mL) to each centrifuge bottle and mix (Note 4).NOTE 4It may not be necessary to add the iron carrier if a sufficientamount of iron is present in
46、the soil.10.12 Add NaOH (50 %) with mixing to each bottle to a pHof about 9 (using pH paper) to precipitate ferric hydroxide.Add5 to 10 mL excess NaOH and mix for 1 min.10.13 Centrifuge for approximately 5 min, decant, anddiscard the supernate.10.14 Dissolve each precipitate with about 30 mL HNO3(8M
47、) (60 mL total) saturated with boric acid. (Approximately7 g of boric acid/30 mL HNO3(8M).) Digest in a hot waterbath for 10 min.10.15 Cool and centrifuge for approximately 5 min. Decantthe supernate into the original 250 mL PTFE beaker and save.10.16 Wash each residue with approximately 10 to 20 mL
48、(20 to 40 mL total) of HNO3(8M) saturated with boric acid.Centrifuge for 5 min and combine the supernates with that in10.15. Discard the undigested soil.10.17 Heat the supernate on a hotplate and evaporate toapproximately 5 mL.10.18 Add approximately 30 mL water and heat to dissolvethe salts. Cool a
49、nd transfer into a centrifuge tube.10.19 Add concentrated ammonium hydroxide dropwisewith mixing to a pH of approximately 9 (using pH paper) toprecipitate ferric hydroxide.10.20 Centrifuge and discard the supernate.10.21 Dissolve the precipitate with a volume of concen-trated nitric acid approximately equal to the volume of theprecipitate and transfer using nitric acid (8M) into a 250-mLbeaker.Add nitric acid (8M) to a total volume of approximately75 mL. If the volume of the hydroxide precipitate is consider-ably greater than should be expected from the 10 mg
