1、Designation: C1507 12Standard Test Method forRadiochemical Determination of Strontium-90 in Soil1This standard is issued under the fixed designation C1507; 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is applicable to the determination ofstrontium-90 in soil at levels of detection dependent on counttime, sample size
3、, detector efficiency, background, and chemi-cal yield.1.2 This test method is designed for the analysis of tengrams of soil, previously collected and treated as described inPractices C998 and C999. This test method may not be able tocompletely dissolve all soil matrices. The values stated in SIunit
4、s are to be regarded as the standard.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 establish appro-priate safety and health practices and determine the applica-bility of regulatory lim
5、itations prior to use.2. Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclear MaterialsC998 Practice for Sampling Surface Soil for RadionuclidesC999 Practice for Soil Sample Preparation for the Determi-nation of RadionuclidesD1193 Specification for Reagent WaterD7282 Practice
6、 for Set-up, Calibration, and Quality Controlof Instruments Used for Radioactivity Measurements3. Terminology3.1 For definitions of terms used in this standard, refer toTerminology C859.4. Summary of Test Method4.1 Strontium is extracted from soil with a mixture of nitric,hydrochloric, and hydrofluo
7、ric acids in the presence of stron-tium carrier. Strontium is isolated by extraction chromatogra-phy and evaporated on a planchet for recovery determinationand subsequent beta counting. This test method describes oneof the possible approaches to determine strontium-90 in soil.The chemical yield is t
8、ypically 95 % with a detection limit ofabout 0.004 Bq/g for a ten gram sample.5. Significance and Use5.1 Because soil is an integrator and a reservoir of long-lived radionuclides, and serves as an intermediary in severalpathways of potential exposure to humans, knowledge of theconcentration of stron
9、tium-90 in soil is essential. A soilsampling and analysis program provides a direct means ofdetermining the concentration and distribution of radionuclidesin soil. A soil analysis program has the most significance forthe preoperational monitoring program to establish baselineconcentrations prior to
10、the operation of a nuclear facility. Soilanalysis, although useful in special cases involving unexpectedreleases, may not be able to assess small incremental releases.6. Interferences6.1 The presence of strontium-89 in the sample may bias thereported strontium-90 results using this method.6.2 Large
11、concentrations of strontium, calcium, barium, orlead in the soil sample could interfere with the extractionchromatographic separation by loading the column with theseelements. Section 12.1 discusses procedures for accounting forthe stable strontium.6.3 The final strontium form is a nitrate salt and
12、it ishygroscopic. Care must be taken when determining the mass ofthe final precipitate to avoid mass fluctuations and changes inphysical form or self-absorption due to water absorption fromthe atmosphere.7. Apparatus7.1 Beta Particle CounterA shielded low-backgroundproportional detector with appropr
13、iate electronics and compu-tational capabilities to control operations. The efficiency of thesystem should be greater than 35 percent for strontium-90 witha background of less than a few counts per minute. PracticeD7282 may contain other useful information on the set-up,1This test method is under th
14、e jurisdiction of ASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved June 1, 2012. Published June 2012. Originallyapproved in 2001. Last previous edition approved in 2007 as C1507 07E01. DOI:10.1520/C1507-12.2For
15、 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700
16、, West Conshohocken, PA 19428-2959, United States.calibration, and usage of such instrumentation. The measure-ment of strontium-90 and yttrium-90 can also be conducted byliquid scintillation spectrometry provided equivalency is dem-onstrated.7.2 Counting DishesTypically, 50 mm diameter, 6 mmdeep, st
17、ainless steel counting dishes, although other sizes maybe used that are compatible with the measurement instrumen-tation.7.3 Heat Lamp.7.4 Muffle Furnace.7.5 Whatman #2 Filter Paper or equivalent.7.6 Borosilicate Glass Erlenmeyers Flasks and Beakers.7.7 PTFE Beakers.7.8 Stir/Hot Plate.7.9 Polytetraf
18、luoroethylene (PTFE) Coated Magnetic StirBars.8. Reagents8.1 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 Analytical Reagents of the American Chemical Society,
19、where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood
20、 to mean reagent water as definedin Specification D1193, Type III.8.3 Strontium CarrierDissolve 10.00 grams of Sr(NO3)2in 0.1M HNO3and dilute to one liter with 0.1M HNO310 mgSr(NO3)2per mL. If insoluble material is observed, filter thecarrier solution through 0.1-0.45 m filter media.8.4 29 M Hydrofl
21、uoric Acid (48 %)Concentrated hydro-fluoric acid.8.5 12 M Hydrochloric Acid (sp gr 1.19)Concentratedhydrochloric acid.8.6 16 M Nitric Acid (sp gr 1.42)Concentrated nitric acid.8.7 8 M Nitric AcidMix one volume of concentrated nitricacid with one volume of water.8.8 0.1 M Nitric AcidAdd 6.25 mL conce
22、ntrated nitricacid to water and dilute to one liter.8.9 0.05 M Nitric AcidAdd 3.10 mL concentrated nitricacid to water and dilute to one liter.8.10 Extraction Chromatographic ColumnA2 mL extrac-tion chromatographic column (including funnel reservoir)containing 4.4(5)-di-t-butylcyclohexane 18crown-6
23、(crownEther) in 1octanol on an inert chromatographic support.49. Standardization and Calibration9.1 Standardization of Strontium CarrierThe standardiza-tion of the strontium carrier should be conducted in triplicate.Standardization of the strontium carrier and yield calculationsmay also be performed
24、 by plasma spectrometry analysisprovided equivalency is demonstrated.9.1.1 Clean and weigh the counting dish.9.1.2 Pipette 1.000 mL of strontium carrier solution into thecounting dish.9.1.3 Place the counting dish in a fume hood under a heatlamp until the sample is at constant weight.9.1.4 Cool the
25、sample counting dish and counting dish/residue and reweigh.9.1.5 Average the three net residue weights and record theaverage as the amount of the strontium nitrate in the carrier.9.2 Calibration of Beta Counting System for Strontium-90This calibration should be carried out in triplicate for eachvolu
26、me of carrier pipetted.9.2.1 Pipette 0.500, 1.000, 1.500 and 2.000 mL of strontiumcarrier into separate small beakers and label. If the samples areexpected to contain significant amounts of stable strontium,larger volumes of strontium carrier should be used provided theresin volume is adjusted accor
27、dingly.9.2.2 To each beaker, add a known amount (approximately2 Bq) of a strontium-90 standard solution traceable to anational standards body.9.2.3 Evaporate the solution to near dryness and redissolveit in 5 mL of the 8 M nitric acid.9.2.4 Transfer the solution to a previously prepared andcondition
28、ed 2 mL strontium extraction chromatographic col-umn which has been conditioned with 5 mL of 8 M nitric acid.9.2.5 Rinse the beaker with 3 mL of 8 M nitric acid and addto the column after the feed has passed through.9.2.6 Wash the column with three 3 mL portions of 8 Mnitric acid, draining after eac
29、h addition. Discard the columneffluent and washes, which contains the yttrium-90.9.2.7 Record the end of the third rinse as strontium-90/yttrium-90 separation time.9.2.8 Elute the strontium with 10 mL of 0.05 M nitric acidand collect in a 25 mL properly labeled clean beaker.9.2.9 Evaporate the stron
30、tium eluate, by using a heat lampor other suitable heat source, on to a previously cleaned and3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Stan
31、dards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.4Sr Resin prepackaged columns from Eichrom Technologies, LLC., Lisle, IL,have been found to be satisfactory for this purpos
32、e. The Eichrom Technologies SrResin is covered by a patent. Interested parties are invited to submit informationregarding the identification of an alternative to this patented item to ASTMInternational headquarters. Your comments will receive careful consideration at ameeting of the responsible tech
33、nical committee, which you may attend.C1507 122weighed counting dish by adding small portions (3 mL) to thedish and allowing each portion to evaporate to near drynessbetween additions.9.2.10 Evaporate all the solution under a heat lamp, or othersuitable heat source, cool, and weigh to constant weigh
34、t.9.2.11 Calculate the residue weight and determine thechemical recovery.9.2.12 Count each standard for 100 minute intervals over-night. Typically, this would result in ten separate measure-ments.9.2.13 Collect the 100 minute count data as a function oftime since separation. Use a computer program t
35、o plot therecovery corrected net count rate and estimate the extrapolationto separation time. Alternatively, determine the mean countingefficiency from each of the counts, correct for yttrium-90ingrowth.9.2.14 Plot the counting efficiency of the strontium-90 as afunction of sample weight to obtain a
36、 counting efficiencycurve. Fit the mass attenuated counting efficiency to a linearexpression and use this expression for each sample to deter-mine the counting efficiency.10. Precautions10.1 Strong acids are used during this analysis. Safetyglasses and gloves must be worn when handling these solu-ti
37、ons. Extreme care should be exercised in using hydrofluoricacid and other hot concentrated acids.10.2 2 Hydrofluoric acid is a highly corrosive acid that canseverely burn skin, eyes, and mucous membranes. Hydroflu-oric acid is similar to other acids in that the initial extent of aburn depends on the
38、 concentration, the temperature, and theduration of contact with the acid. Hydrofluoric acid differsfrom other acids because the fluoride ion readily penetrates theskin, causing destruction of deep tissue layers. Unlike otheracids that are rapidly neutralized, hydrofluoric acid reactionswith tissue
39、may continue for days if left untreated. Due to theserious consequences of hydrofluoric 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
40、contact is essential.11. Sampling11.1 Collect the sample in accordance with Practice C998.11.2 Prepare the sample for analysis in accordance withPractice C999.12. Procedure12.1 The soil sample is analyzed for strontium-90 in dupli-cate. To account for the stable strontium in the soil, the secondaliq
41、uot of the same soil is analyzed without carrier. The analystmust understand the limitations of using duplicate samples.This approach is based on the concept that “identical” chemicalyields are obtained for both samples with and without stablestrontium added. This assumption results in a potentially
42、significant contribution to the uncertainty analysis, as dis-cussed in 14.6. Place two 10.000 gram aliquots of dried soilinto each of two 500 mL Erlenmeyer flasks. Add 2.000 mL ofstrontium carrier into one of the flasks and label.Add no carrierto the other flask and label accordingly. As an alternat
43、ive fordetermining the chemical yield, strontium-85 may be used asan internal standard, but it would be up to the user to determineequivalency. If the indigenous strontium content of the samplehas been previously determined, the amount of strontiumcarrier added may be adjusted and the analysis of th
44、e secondaliquot may not be required.12.2 Ash the samples overnight at 500C in the Erlenmeyerflasks.12.3 Cool, add 75 mL concentrated nitric acid and then 25mL of concentrated hydrochloric acid.12.4 Cover the Erlenmeyer flask and heat on a hot plate inthe fume hood for several hours with stirring usi
45、ng PTFE-coated magnetic stirring bars.12.5 Cool and dilute with an equal volume of water.12.6 Transfer the sample to a 250 mL centrifuge bottle withwater and centrifuge.12.7 Decant the supernate through Whatman #2 24 cmfluted filter paper and save the filtrate.12.8 Transfer the residue remaining in
46、the centrifuge bottlewith a mixture of 75 mL concentrated nitric acid and 25 mLconcentrated hydrochloric acid to the original Erlenmeyer flaskand repeat 12.4 and 12.5.12.9 Filter the solution through Whatman #2 filter paperused in 12.7 and combine the filtrate, without centrifugation,with the origin
47、al supernate from 12.7.12.10 Place the filter in a 400 mL beaker, dry the filter in alow temperature oven and ash overnight at 500 C in a 400 mLbeaker.12.11 Cool and transfer the ash to a 250 mL PTFE beakerwith 15 mL concentrated nitric acid. Add 50 mL concentratedhydrofluoric acid to the PTFE beake
48、r.12.12 Cover the beaker and digest overnight on low heat.12.13 Evaporate to dryness and repeat the acid addition anddigestion in 12.11 and 12.12 one more time if a residueremains.12.14 When there is no residue, add 15 mL concentratednitric acid and evaporate to dryness.12.15 Add 15 mL 8 M nitric ac
49、id, cover, and heat to boilingfor 5 minutes.12.16 Cool and add 50 mL water.12.17 Filter through Whatman #2 filter paper and combinethe filtrate with the original supernate and first filtrate, 12.9.Split the sample in two by volume. This results in two sampleswith carrier and two samples without carrier, each representingfive grams of the original soil sample.12.18 Carefully evaporate to less than 5 mL. Do not allowthe samples to go dry.12.19 Slowly add concentrated nitric acid to bring thevolume up to 5 mL and slowly add an additional 5 mL water toachieve a fina
