1、Designation: C 1507 07Standard Test Method forRadiochemical Determination of Strontium-90 in Soil1This standard is issued under the fixed designation C 1507; 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 (e) 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 s
3、ize, detector efficiency, background, and recov-ery.1.2 This test method is designed for the analysis of tengrams of soil, previously collected and treated as described inPractices C 998 and C 999. This test method may not be ableto completely dissolve all soil matrices. The values stated in SIunits
4、 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 limi
5、tations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 859 Terminology Relating to Nuclear Materials3C 998 Practice for Sampling Surface Soil for RadionuclidesC 999 Practice for Soil Sample Preparation for the Deter-mination of RadionuclidesD 1193 Specification for Reagent Water3. Termino
6、logy3.1 For definitions of terms used in this standard, refer toTerminology C 859.4. Summary of Test Method4.1 Strontium is extracted from soil with a mixture of nitric,hydrochloric, and hydrofluoric acids in the presence of stron-tium carrier. Strontium is isolated by extraction chromatogra-phy and
7、 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 typically 95 % with a detection limit ofabout 0.004 Bq/g for a ten gram sample.5. Significance and Use5.1
8、 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 strontium-90 in soil is essential. A soilsampling and analysis program provides a direct means ofdetermining
9、the concentration and distribution of radionuclidesin soil. A soil analysis program has the most significance forthe preoperational monitoring program to establish baselineconcentrations prior to the operation of a nuclear facility. Soilanalysis, although useful in special cases involving unexpected
10、releases, may not be able to assess small incremental releases.6. Interferences6.1 The presence of strontium-89 in the sample will inter-fere with the determination of strontium-90.6.2 Large concentrations of strontium, calcium, barium, orlead in the soil sample could interfere with the extractionch
11、romatographic 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 it ishygroscopic. Care must be taken when determining the mass ofthe final precipitate to avoid mass fluctuat
12、ions and changes inphysical form or self-absorption due to water absorption fromthe atmosphere.7. Apparatus7.1 Beta Particle CounterA shielded low-backgroundproportional detector with appropriate electronics and compu-tational capabilities to control operations. The efficiency of thesystem should be
13、 greater than 35 percent for strontium-90 witha background of less than a few counts per minute. Themeasurement of strontium-90 can also be conducted by liquidscintillation spectrometry provided equivalency is demon-strated.7.2 Counting DishesTypically, 50 mm diameter, 6 mmdeep, stainless steel coun
14、ting dishes, although other sizes maybe used that are compatible with the measurement instrumen-tation.7.3 Heat Lamp.7.4 Muffle Furnace.1This test method is under the jurisdiction of ASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Cur
15、rent edition approved June 1, 2007. Published July 2007. Originally approvedin 2001. Last previous edition approved in 2006 as C 1507 01 (2006).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards v
16、olume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.5 Whatman #2 Filter Paper.7.6 Borosilicate Glass Erlenmeyers Flasks and Beakers.7.7 PTFE
17、Beakers.7.8 Stir/Hot Plate.7.9 Teflon Coated Magnetic Stir Bars.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
18、 Chemical Society,where such specifications are available.4Other 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 s
19、hall be understood to mean reagent water as definedin Specification D 1193, 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 med
20、ia.8.4 29 M Hydrofluoric Acid (48 %)Concentrated hydrof-luoric 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 Ac
21、idAdd 6.25 mL concentrated 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 ColumnA 2 mLstrontium-specific extraction chromatographic column includ-ing funnel reservoir.59. Standardi
22、zation 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 by plasma spectrometry analysisprovided equivalency is demonstrated.9.1.1
23、 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 sample counting dish and counting dish/residue and reweigh.9.1.5 Average t
24、he 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 eachvolume of carrier pipetted.9.2.1 Pipette 0.500, 1.000, 1.500 and 2.000 mL of s
25、trontiumcarrier 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 accordingly.9.2.2 To each beaker, add a known amount (approximately2 Bq) of a s
26、trontium-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 andconditioned 2 mL strontium extraction chromatographic col-umn which has been condit
27、ioned 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 each addition. Discard the columneffluent and washes, which contains the yttr
28、ium-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 strontium eluant, by using a heat lampor other suitable heat source, on to a pr
29、eviously cleaned andweighed counting dish by adding small portions (ca. 3 mL) tothe dish 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 weight.9.2.11 Calculate the
30、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 to plot therecovery corr
31、ected 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 counting efficiencycur
32、ve. 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-tions. Extreme care shoul
33、d 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. Hydrofluo-ric acid is similar to other acids in that the initial extent of a4Reagent Chemicals, American Chemical Soci
34、ety Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Reagent Chemicals and Standards, byJoseph Rosin, D. Van Nostrand Co., Inc., New York, NY, and the United StatesPharmacopeia.5Sr Resin prepackaged c
35、olumns from Eichrom Technologies, LLC., Darien, IL,have been found to be satisfactory for this purpose.C1507072burn depends on the concentration, the temperature, and theduration of contact with the acid. Hydrofluoric acid differsfrom other acids because the fluoride ion readily penetrates theskin,
36、causing destruction of deep tissue layers. Unlike otheracids that are rapidly neutralized, hydrofluoric acid reactionswith tissue 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. Util
37、izationof appropriate laboratory controls (hoods) and wearing ad-equate personal protective equipment to protect from skin andeye contact is essential.11. Sampling11.1 Collect the sample in accordance with Practice C 998.11.2 Prepare the sample for analysis in accordance withPractice C 999.12. Proce
38、dure12.1 The soil sample is analyzed for strontium-90 in dupli-cate. To account for the stable strontium in the soil, the secondaliquot of the same soil is analyzed without carrier. Theanalysis must understand the limitations of using duplicatesamples. This approach is based on the concept that “ide
39、ntical”chemical yields are obtained for both samples with and withoutstable strontium added. This assumption results in a potentiallysignificant 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
40、 2.000 mL ofstrontium carrier into one of the flasks and label.Add no carrierto the other aliquot. As an alternative for determining thechemical yield, strontium-85 may be used, but it would be upto the user to determine equivalency. If the indigenous stron-tium content of the sample has been previo
41、usly determined, theamount of strontium carrier added may be adjusted and theanalysis of the second aliquot may not be required.12.2 Ash the samples overnight at 500C.12.3 Cool, add 75 mL concentrated nitric acid and then 25mL of concentrated hydrochloric acid.12.4 Cover the Erlenmeyer flask and hea
42、t on a hot plate inthe fume hood for several hours with stirring using Teflon-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 filt
43、er paper and save the filtrate.12.8 Transfer the residue remaining in 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
44、 12.7 and combine the filtrate, without centrifugation,with the original supernate from 12.7.12.10 Dry the filter in a low temperature oven and ashovernight at 500 C in a 400 mL beaker.12.11 Cool and transfer the ash to a 250 mL PTFE beakerwith 15 mL concentrated nitric acid. Add 50 mL concentratedh
45、ydrofluoric acid to the PTFE beaker.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 dry
46、ness.12.15 Add 15 mL 8 M nitric acid, 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 ca
47、rrier and two samples without carrier, each with fivegrams of soil.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 final acid concentration of 8
48、M HNO3.12.20 Preparea2mLextraction column and condition with5mLof8M nitric acid.12.21 Transfer the sample to the column incrementally anddrain to the top of the column.12.22 Rinse the beaker with 3 mL of 8 M nitric acid and addto the column.12.23 Rinse the column three times with 3 mL portions of 8M
49、 nitric acid, draining completely before the next addition.Discard the rinses.12.24 Record this time as the strontium-90/yttrium-90 sepa-ration time.12.25 Elute the strontium with 10 mL of 0.05 M nitric acidand collect in a clean labeled beaker.12.26 Evaporate the strontium eluant onto a cleaned andweighed counting dish by adding small portions (ca. 3 mL) tothe dish in a hood under a heat lamp and allowing each portionto evaporate to near dryness between additions.12.27 Evaporate completely, cool, and reweigh to constantweight.13. Calculations13.1 Calculate the resi
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