1、Designation: C1507 071Standard 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.1NOTETypos in the equation in Section 14.7 were editorially corrected in March 2010.1. Scope1.1 This test method is applicable to the determinat
3、ion ofstrontium-90 in soil at levels of detection dependent on counttime, sample size, 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 C998 and C999. This test method may n
4、ot be able tocompletely dissolve all soil matrices. The values stated in SIunits 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
5、 safety and health practices and determine the applica-bility of regulatory limitations 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 Det
6、ermi-nation of RadionuclidesD1193 Specification for Reagent Water3. 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 hydrofluoric acids in the presence of s
7、tron-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 typically 95 % with a detection
8、 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 strontium-90 in soil is essential.
9、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 the operation of a nuclear fac
10、ility. 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 will inter-fere with the determination of strontium-90.6.2 Large concentrations of strontium, calciu
11、m, 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 it ishygroscopic. Care must be take
12、n when determining the mass ofthe final precipitate to avoid mass fluctuations and changes inphysical form or self-absorption due to water absorption fromthe atmosphere.1This test method is under the jurisdiction of ASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommi
13、ttee C26.05 on Methods ofTest.Current edition approved June 1, 2007. Published July 2007. Originally approvedin 2001. Last previous edition approved in 2006 as C1507 01 (2006). DOI:10.1520/C1507-07.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service
14、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, West Conshohocken, PA 19428-2959, United States.7. Apparatus7.1 Beta Particle CounterA shielded
15、low-backgroundproportional detector with appropriate 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. Themeasurement of strontium-90 can also be con
16、ducted by liquidscintillation spectrometry provided equivalency is demon-strated.7.2 Counting DishesTypically, 50 mm diameter, 6 mmdeep, stainless 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 Wha
17、tman #2 Filter Paper.7.6 Borosilicate Glass Erlenmeyers Flasks and Beakers.7.7 PTFE 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 co
18、nform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,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 t
19、he determination.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood 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 insol
20、uble material is observed, filter thecarrier solution through 0.1-0.45 m filter media.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
21、 one volume of concentrated nitricacid with one volume of water.8.8 0.1 M Nitric AcidAdd 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 ColumnA2 mLstrontium-sp
22、ecific extraction chromatographic column includ-ing funnel reservoir.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 p
23、erformed 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 C
24、ool the 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
25、eachvolume 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 adjust
26、ed accordingly.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 andc
27、onditioned 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 a
28、fter each 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 t
29、he strontium eluant, by using a heat lampor other suitable heat source, on to a previously 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 o
30、thersuitable heat source, cool, and weigh to constant weight.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
31、 function oftime since separation. Use a computer program to 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.3Reagent Chemicals, American Chemical
32、Society 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.4Sr Resin prepacka
33、ged columns from Eichrom Technologies, LLC., Darien, IL,have been found to be satisfactory for this purpose.C1507 07129.2.14 Plot the counting efficiency of the strontium-90 as afunction of sample weight to obtain a counting efficiencycurve. Fit the mass attenuated counting efficiency to a linearexp
34、ression 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 should be exercised in using hydrofluoricacid and other hot concent
35、rated 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 aburn depends on the concentration, the temperature, and theduration of contact with the acid. Hydrofluor
36、ic 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 may continue for days if left untreated. Due to theserious consequences of hydrofluor
37、ic 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.11. Sampling11.1 Collect the sample in accordance with Practice
38、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 secondaliquot of the same soil is analyzed without carrier. Theanalysis must understand the lim
39、itations of using duplicatesamples. This approach is based on the concept that “identical”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 t
40、wo 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 aliquot. As an alternative for determining thechemical yield, strontium-85 may be used, but it would be upto the user to determ
41、ine equivalency. If the indigenous stron-tium content of the sample has been previously 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
42、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 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 wit
43、hwater 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 the centrifuge bottlewith a mixture of 75 mL concentrated nitric acid and 25 mLconcentrated hydrochloric acid to the original Erlenmeyer flaskand r
44、epeat 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 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
45、to a 250 mL PTFE beakerwith 15 mL concentrated nitric acid. Add 50 mL concentratedhydrofluoric 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.
46、14 When there is no residue, add 15 mL concentratednitric acid and evaporate to dryness.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 f
47、iltrate, 12.9.Split the sample in two by volume. This results in two sampleswith carrier 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
48、 and slowly add an additional 5 mL water toachieve a final acid concentration of 8 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 ac
49、id and addto the column.12.23 Rinse the column three times with 3 mL portions of 8M 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 Evaporat
