1、Designation: D 3454 05Standard Test Method forRadium-226 in Water1This standard is issued under the fixed designation D 3454; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indica
2、tes 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 measurement of soluble,suspended, and total radium-226 in water in concentrationsabove 3.7 3 103Bq/L. This test method is not applicab
3、le tothe measurement of other radium isotopes.1.2 This test method may be used for quantitative measure-ments by calibrating with a radium-226 standard, or for relativemeasurements by comparing the measurements made witheach other.1.3 This test method does not meet the current requirementsof Practic
4、e D 2777.1.4 The values stated in SI units are to be regarded as thestandard. The inch-pound units given in parentheses are forinformation only.1.5 Hydrofluoric acid (HF) is very hazardous and should beused in a well-ventilated hood. Wear rubber gloves, safetyglasses or goggles, and a laboratory coa
5、t. Avoid breathing anyHF fumes. Clean up all spills promptly and wash thoroughlyafter using HF.1.6 This standard does not purport to address all of theother safety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and hea
6、lth practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 2777 Practice for Determination of Precision and BiasApplicable Methods of Committee D19 on Wat
7、erD 3370 Practices for Sampling Water from Closed ConduitsD 3649 Practice for High-Resolution Gamma-Ray Spec-trometry of WaterD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3. Terminology3.1 DefinitionsFor definitions of terms used in this testm
8、ethod, refer to Terminology D 1129, and to other publishedglossaries.34. Summary of Test Method4.1 This test method4is based on the emanation andscintillation counting of222Rn, a gaseous daughter productof226Ra, from a solution.4.2226Ra is collected from water by coprecipitation on arelatively large
9、 amount of barium sulfate. The barium-radiumsulfate is decomposed by fuming with phosphoric acid, and theresulting glassy melt is dissolved by evaporation with dilutehydrochloric acid to form soluble barium-radium phosphatesand chlorides. These salts are dissolved and the solution isstored for ingro
10、wth of222Rn. After a suitable ingrowth period,the radon gas is removed from the solution by purging with gasand transferred to a scintillation counting chamber. About 4 hafter222Rn collection, the scintillation chamber is counted foralpha activity. The226Ra concentration is calculated from thealpha
11、count rate of222Rn and its immediate daughters. Theradioactive decay characteristics of226Ra and its immediatedecay progeny are listed in Table 1.5. Significance and Use5.1 The most prevalent of the five radium isotopes in groundwater, having a half life greater than one day, are226Raand228Ra. These
12、 two isotopes also present the greatest healthrisk compared to the other naturally occurring nuclides of equalconcentrations if ingested via the water pathway.5.2 Although primarily utilized on a water medium, thistechnique may be applicable for the measurement of the226Ra1This test method is under
13、the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemi-cal Analysis.Current edition approved Feb. 1, 2005. Published February 2005. Originallyapproved in 1975. Last previous edition approved in 1997 as D 3454 97.2For referenced
14、 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.3American National Standard Glossary of Terms in Nuclear Science andTechnolo
15、gy, N1.1-1967.4This test method is based on a previously published method by Rushing, D.E.,Garcia, W.J., and Clark, D.A. “The Analysis of Effluents and EnvironmentalSamples from Uranium Mills and of Biological Samples for Radium, Polonium andUranium,” Radiological Health and Safety in Mining and Mil
16、ling of NuclearMaterials, Vol. II, IAEA, Vienna, Austria, 1964), p. 187.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.content of any media once the medium has been completelydecomposed and put into an aqueous solution.5.3 The gener
17、al methodology and basis of this technique aresimilar to the methodology “226Ra in Drinking Water (RadonEmanation Technique)” as described in the document EPA-600/4-80-032.56. Interferences6.1 Only the gaseous alpha-emitting radionuclides interfere,namely, radon-219 and radon-220. Their half lives a
18、re 3.9 and54.5 s respectively; their presence indicates the presence oftheir parents,223Ra and224Ra. These short-lived radonisotopes decay before the222Rn is counted; it is their alpha-emitting decay products that would interfere. These interfer-ences are very rare in water samples but are frequentl
19、yobserved in certain uranium mill effluents.7. Apparatus7.1 Radon Bubbler6(Fig. 1).7.2 Radon Scintillation Chamber (also known as LucasCell) (Fig. 2).7.3 Manometer, open-end capillary tube or vacuum gagehaving a volume which is small compared to the volume of thescintillation chamber, 0 760 mm Hg (F
20、ig. 3).7.4 Gas Purification Tube, 7 to 8 mm outside diameterstandard wall glass tubing, 100 mm long, constricted at lowerend to hold a glass wool plug (Fig. 3). The upper half of thetube is filled with magnesium perchlorate and the lower halfwith a sodium hydrate-asbestos absorbent.7.5 Scintillation
21、 Counter Assembly, consisting of a 50 mm(2 in.) or more in diameter photomultiplier tube mounted in alight-tight housing and coupled to the appropriate preamplifier,high-voltage supply, and scaler. A high-voltage safety switchshould open automatically when the light cover is removed toavoid damage t
22、o the photomultiplier tube. The preamplifiershould incorporate a variable gain adjustment. The countershould be equipped with a flexible ground wire which isattached to the chassis photomultiplier tube by means of analligator clip or similar device. The operating voltage isascertained by determining
23、 a plateau using222Rn in thescintillation chamber as the alpha source. The slope of theplateau should not exceed 2 %/100 V. The counter and thescintillation chamber should be calibrated and used as a unitwhen more than one counter is available. The backgroundcounting rate for the counter assembly wi
24、thout the scintillationchamber should range from 0.00 to 0.0005 cps.7.6 Membrane Filters, 0.45-m pore size.7.7 Silicone Grease, high-vacuum, for bubbler stopcocks.7.8 Platinum Ware, crucibles, 20 to 30 mL, and one 500-mLcapacity dish. Platinum ware is cleaned by immersing androtating in a molten bat
25、h of potassium pyrosulfate, removing,cooling, and rinsing in hot tap water, digesting in hot 6M HCl,rinsing in water, and finally flaming over a burner.7.9 Laboratory GlasswareGlassware may be decontami-nated before and between uses by heating for1hinEDTA-Na2CO3decontaminating solution at 90 to 100C
26、, then rinsingin water, in 1M HCl and again in water.5“Radium-226 in Drinking Water (Radon Emanation Technique),” PrescribedProcedures for Measurement of Radioactivity in Drinking Water, August 1980.6The sole source of supply of the radon bubbler known to the committee at thistime is Corning Glass W
27、orks, Special Sales Section, Corning, N.Y. 11830. If you areaware of alternative suppliers, please provide this information to ASTM Interna-tional Headquarters. Your comments will receive careful consideration at a meetingof the responsible technical committee1, which you may attend.TABLE 1 Radioact
28、ive Decay Characteristics of Radium-226 andIts DaughtersRadionuclide Half-life Mode of Decay226Ra 1600 years a222Rn 3.82 days a218Po 3.10 min a214Pb 26.8 min b, g214Bi 19.9 min b, g214Po 164/3 s a210Pb 22.2 years b, gFIG. 1 Radon BubblerD34540528. Reagents and Materials8.1 Purity of ReagentsReagent
29、grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society.7Other grades may be used, provided it is first ascertained thatthe reagent is of suffici
30、ently high purity to permit its usewithout lessening the accuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean conforming to Specifi-cation D 1193, Type III.8.3 Radioactive Purity of ReagentsRadioactive purityshall be such that the
31、 measured results of blank samples do notexceed the calculated probable error of the measurement or arewithin the desired precision.8.4 Ammonium Sulfate Solution (100 g/L)Dissolve 10 gof ammonium sulfate (NH4)2SO4) in water and dilute to 100mL.8.5 Barium Chloride Carrier Solution Stock, (17.8 g/L)Di
32、ssolve 17.8 g of barium chloride (BaCl22H2O) in water anddilute to 1 L. This solution will contain 10 mg Ba+/mL.8.6 Barium-133 Tracer Solution(approximately 3 kBq/mL).8.7 Barium Chloride Carrier Solution, WorkingAdd 100mL of barium chloride carrier stock solution and 10 mL ofbarium-133 tracer soluti
33、on to 890 mL of water and mixthoroughly. This solution will contain approximately1gofBa+/L.Allow to stand for 24 h and filter through a membranefilter.8.8 EDTA-Sodium Carbonate Decontaminating SolutionDissolve 10 g of disodium ethylenediaminetetraacetate and 10g of sodium carbonate (Na2CO3) in water
34、 and dilute to 1 L.8.9 FluxTo a large platinum dish (about 500-mLcapacity)add 30 mg of BaSO4,65.8gofK2CO3,50.5gofNa2CO3, and33.7gofNa2B4O710 H2O. Mix well and heat cautiously untilthe water is expelled; fuse and mix thoroughly by swirling.Cool flux, grind it in a porcelain mortar to pass a U. S. Sta
35、ndardNo. 10 (2.00-mm) (or finer) sieve. Store in an airtight bottle.(Flux can be prepared in smaller batches.)7“Reagent Chemicals,American Chemical Society Specifications,”Am. Chemi-cal Soc., Washington, DC. For suggestions on testing of reagents not listed by theAmerican Chemical Society, see “Anal
36、ar Standards for Laboratory Chemicals,”BDH Ltd., Poole, Dorset, U.K., and the “United States Pharmacopeia,” and NationalFormulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.FIG. 2 Radon Scintillation ChamberFIG. 3 De-emanation AssemblyD34540538.10 Hydrochloric Acid (sp gr 1.19)Conce
37、ntrated hydro-chloric acid (HCl).8.11 Hydrochloric Acid Solution 6M (1 + 1)Mix 1 vol-ume of concentrated HCl (sp gr 1.19) with 1 volume of water.8.12 Hydrochloric Acid Solution 1M (1 + 11)Mix 1 vol-ume of concentrated HCl (sp gr 1.19) with 11 volumes ofwater.8.13 Hydrochloric Acid Solution 0.24M (1
38、+ 49)Mix 1volume of concentrated HCl (sp gr 1.19) with 49 volumes ofwater.8.14 Hydrochloric Acid Solution 0.1M (1 + 119)Mix 1volume of concentrated HCl (sp gr 1.19) with 119 volumes ofwater.8.15 Hydrofluoric Acid (sp gr 1.15)Concentrated hydrof-luoric acid (HF). Use extreme caution.8.16 Hydrogen Per
39、oxide3%(1+9)Mix 1 volume ofH2O2(30 %) with 9 volumes of water.8.17 Magnesium PerchlorateAnhydrous magnesium per-chlorate Mg(ClO4)2.8.18 Phosphoric Acid (sp gr 1.69)Concentrated phospho-ric acid (H3PO4).8.19 Radium Standard Solution (0.37 Bq/mL).6,88.20 Sodium Hydroxide-Coated Silicate Absorbent, Pro
40、pri-etary,6,98 to 20 mesh.8.21 Sulfuric Acid (sp gr 1.84)Concentrated sulfuric acid(H2SO4).8.22 Sulfuric Acid Solution 0.05M (1 + 359)Mix 1 vol-ume of concentrated H2SO4(sp gr 1.84) with 359 volumes ofwater. This solution is 0.1 N. Slowly add acid to water.8.23 Helium, in a high-pressure cylinder wi
41、th a two-stagepressure regulator and needle valve.9. Sampling9.1 Collect the sample in accordance with the applicablestandards as described in Practices D 3370.10. Calibration and Standardization10.1 Close the inlet stopcock of a bubbler, (Note 1) add 5mL of BaCl22H2O carrier solution, 1 mL of conce
42、ntrated HCl(sp gr 1.19), 3 mL (1.1 Bq) of standard radium solution and fillthe bubbler23 to34 full with water.NOTE 1Before using, test bubblers by placing about 10 mL of waterin them and passing air through them at the rate of 3 to 5 mL/min. Thisshould form many fine bubbles rather than a few large
43、ones. Do not usebubblers requiring excessive pressure to initiate bubbling. Reject unsatis-factory bubblers. Cornings “medium-porosity” fritted glass disks areusually satisfactory.10.2 Insert the outlet stopcock into the bubbler with thestopcock open. Adjust the helium regulator (diaphragm) valveso
44、that a very slow stream of gas will flow with the needlevalve open.Attach the helium supply to the inlet of bubbler andadjust the inlet pressure to produce a froth a few millimetresthick. Establish a zero ingrowth time by purging the liquid withhelium for 15 to 20 min.10.3 In rapid succession, close
45、 the inlet stopcock, removethe gas connection, and the close outlet stopcock. Record thedate and time and store the bubbler preferably for 2 to 3 weeksbefore collecting and counting the222Rn.10.4 Attach a scintillation chamber as shown in Fig. 3;substitute a glass tube with a stopcock for the bubble
46、r so thatthe helium gas can be turned on and off conveniently. Open thestopcock on the scintillation chamber; close the stopcock to thegas and gradually open the stopcock to vacuum source toevacuate the cell. Close the stopcock to the vacuum source andcheck the manometer reading for 2 min to test th
47、e system,especially the scintillation chamber for leaks. If leaks aredetected they should be identified and sealed.10.5 Open the stopcock to the helium gas and allow the gasto enter the chamber slowly until atmospheric pressure isreached. Close all the stopcocks.10.6 Place the scintillation chamber
48、on the photomultipliertube (in a light-tight housing), wait 10 min, and obtain abackground count rate (preferably over a period of at least 100min). Phototube must not be exposed to external light with thehigh voltage applied.10.7 With the scintillation chamber and bubbler in positionsindicated in F
49、ig. 3 and all stopcocks closed, open the stopcockto vacuum and then to the scintillation chamber. Evacuate thescintillation cell and the gas purification system. Close thestopcock to vacuum and check for leaks as in 10.4.10.8 Adjust the helium regulator (diaphragm) valve so thata very slow stream of gas will flow with the needle valve open.Attach the helium supply to the inlet of the bubbler.10.9 Very cautiously open the bubbler outlet stopcock toequalize pressure and transfer all or most of the fluid in theinlet side arm to the bubbler chamber
