1、Designation: C1475 05 (Reapproved 2010)1Standard Guide forDetermination of Neptunium-237 in Soil1This standard is issued under the fixed designation C1475; 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.1NOTEEditorial changes were made throughout in June 2010.1. Scope1.1 This guide covers the determination of neptunium-237in soil by means of radi
3、ochemical separations and alphaspectrometry. This guide provides options in the selection ofsample preparation, separation, and measurement. Althoughneptunium-237 is not a component of global fallout, it is aproduct of production reactors and spent fuel processing. Thisguide is designed for analysis
4、 of ten grams of soil previouslycollected and treated in accordance with Practices C998 andC999. Larger-size samples of environmental soil may also beanalyzed, as long as the concentrations of interferences such asuranium and thorium are at or near environmental concentra-tions. Depending on the cho
5、ice of a sample dissolution method,all chemical forms of neptunium may not be completelysolubilized. This guide should allow the determination ofneptunium-237 concentrations from sub becquerel per gramlevels to applicable standards depending on count time, samplesize, detector efficiency, background
6、, and tracer yield.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.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 standar
7、d to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 8.2. Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclear MaterialsC998 Practice for Sampli
8、ng Surface Soil for RadionuclidesC999 Practice for Soil Sample Preparation for the Determi-nation of RadionuclidesC1000 Test Method for Radiochemical Determination ofUranium Isotopes in Soil by Alpha SpectrometryC1001 Test Method for Radiochemical Determination ofPlutonium in Soil by Alpha Spectrosc
9、opyC1163 Practice for Mounting Actinides for Alpha Spec-trometry Using Neodymium FluorideC1284 Practice for Electrodeposition of the Actinides forAlpha SpectrometryC1317 Practice for Dissolution of Silicate or Acid-ResistantMatrix Samples3C1342 Practice for Flux Fusion Sample Dissolution3C1387 Guide
10、 for the Determination of Technetium-99 inSoilC1412 Practice for Microwave Oven Dissolution of GlassContaining Radioactive and Mixed Wastes3D1193 Specification for Reagent WaterD1890 Test Method for Beta Particle Radioactivity of WaterD3084 Practice for Alpha-Particle Spectrometry of WaterD4962 Prac
11、tice for NaI(Tl) Gamma-Ray Spectrometry ofWater2.2 Other Documents:IEEE/ASTM SI-10 Standard for the Use of the InternationalSystem of Units (SI): The Modern Metric System3. Summary of Guide3.1 This guide may be used to determine neptunium-237 insoil at potential release sites.Aneptunium-239 yield mo
12、nitor isadded to the soil aliquot and the sample solubilized by one ofseveral methods, such as those described in Guide C1387. Theneptunium is separated from the resulting solution using anextraction chromatography column. A valence adjustment isperformed prior to loading the sample onto the conditi
13、onedchromatography column. The sample is passed through thecolumn, which retains the neptunium in the +4 oxidation state.The column is washed to remove interferences and selectivelyeluted with dilute acid. The samples are prepared for measure-ment by neodymium fluoride co-precipitation or electrodep
14、o-sition, and the neptunium-237 content determined by alphaspectrometry. The neptunium-239 yield monitor is determinedby beta or gamma-ray counting.1This guide is under the jurisdiction of ASTM Committee C26 on Nuclear FuelCycle and is the direct responsibility of Subcommittee C26.05 on Methods of T
15、est.Current edition approved June 1, 2010. Published June 2010. Originallyapproved in 2000. Last previous edition approved in 2005 as C1475 05. DOI:10.1520/C1475-05R10E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Ann
16、ual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-
17、2959, United States.4. Significance and Use4.1 A soil sampling and analysis program provides a directmeans of determining the concentration and distribution ofradionuclides in soil. The presence and extent of neptunium-237 is of particular interest because it is one of the more mobiletransuranics in
18、 terms of migration and plant uptake. Since soilis an integrator and a reservoir on long-lived radionuclides, andserves as an intermediary in several pathways of potentialimportance to humans, knowledge of the concentration ofneptunium-237 in soil is essential.5. Interferences5.1 Phosphates present
19、in the sample matrix will interferewith the separation chemistry. Aluminum nitrate may be addedto the load solution to minimize this problem.5.2 High concentrations of uranium or thorium can overloadthe column, resulting in low recoveries of neptunium orspectral interferences. A preliminary separati
20、on may be re-quired to avoid spectral interference from uranium, see TestMethod C1000. The presence of uranium-233 and uranium-234 could cause spectral interferences with the neptunium-237determination.6. Apparatus6.1 Apparatus for the sample dissolution and measurementare identified within the sele
21、cted test method.6.2 Extraction Columns, with a bed volume of severalmillilitres for the extraction chromatography resin.47. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specification
22、s of the Commit-tee on Analytical Reagents of the American Chemical Societywhere such specifications are available.5Other 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.7.2 Purity
23、 of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedin Specification D1193.7.3 Aluminum Nitrate Hydrate Al(NO3)39H2O.7.4 Aliphatic Quaternary Amine Extraction Chromatogra-phy Resin.47.5 Ferrous Sulfamate Fe(SO3NH2)2, 1.0 MDissolve38.8 g of sulf
24、amic acid (NH2SO3H) and 11.6 g of iron powderin approximately 150 mL of water. Stir while heating untildissolved and then dilute to 200 mL with water. Prepare fresheach week or keep under a nitrogen blanket to minimizeoxidation.7.6 Hydrofluoric Acid (48 to 51 %)Concentrated hydrof-luoric acid (HF).7
25、.7 Iron Powder.7.8 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).7.9 Nitric Acid, 3.0 MAdd 189 mL of concentrated nitricacid to 400 mL of water and dilute to 1.0 L with water and mix.7.10 2.5 M Nitric Acid-0.5 M Aluminum NitrateDissolve187.6 g of aluminum nitrate in about 500 mL of water, a
26、dd 159mL of concentrated nitric acid, and dilute to 1.0 L.7.11 0.02 M Nitric Acid-0.02 M Hydrofluoric AcidAdd1.25 mL of concentrated nitric acid and 0.7 mL of concentratedhydrofluoric acid to 800 mL of water and dilute to 1.0 L withwater and mix.7.12 Radiometric Yield TracerNeptunium-239 is nor-mall
27、y used as a yield monitor in the determination ofneptunium-237. Where beta counting is used to determine theneptunium-239 yield, a relatively low amount of activity, forexample, 5 to 15 Bq, is typically required to obtain the desiredprecision with a 60-min count duration. Another option is theadditi
28、on of a known quantity of americium-243, in secularequilibrium with neptunium-239, directly to the sample. Thisapproach has the advantage of allowing the use of americium-243 solutions of NIST-traceable activity. Where gamma-raycounting is used to determine the neptunium-239 yield, a largeramount of
29、 activity, for example, 120 to 1200 Bq, may berequired to obtain the desired precision with a 10-min countduration dependent on the use of a NaI(TI) or HPGe detector.In this situation, it may be preferred to obtain the neptunium-239 from an americium-243 8cow.6This approach has theadvantage of conse
30、rving the americium-243 parent with theneptunium-239 activity being replenished over time. However,it has the disadvantage that the neptunium-239 activity of themilked solution must be determined with high precision inorder to not adversely impact the precision of the sampleneptunium-237 activity de
31、termination.7.13 Sodium Nitrite (NaNO2).7.14 Sodium Nitrite, 3.0 MDissolve 2.1 g of sodiumnitrite in 10 mL of water. Prepare fresh daily.7.15 If prepacked columns are not available, prepare theresin by combining it with an equal volume of water, mix well,and allow to settle overnight. Decant the sup
32、ernatant water.Prepare a column for each sample by pouring resin into eachcolumn. Adjust the settled resin bed volume to approximately2 mL. Prepare only enough resin that is needed for use eachday.7.16 The use of dry-packed cartridges of the extractionchromatography resin in combination with a vacuu
33、m manifoldsystem has been found acceptable. When using vacuum-assisted flow, it is essential to ensure that flow rates do notexceed 1 mL/min for load solutions and strip solutions, and 24Prepacked columns of TEVAResin from Eichrom Technologies, Inc., Lisle, IL,have been found to be satisfactory for
34、this purpose.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United Stat
35、es Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.6Information on the generation and use of americium-243 cows to obtainneptunium-239 can be obtained from: Garraway, J., and Wilson, P. D., “Preparationof Np-239 by Separation from the Parent Am-243,” Jour
36、nal of the Less-CommonMetals, 91, 1983, L13-L16, and Bubernak, J., Lew, M. S., and Matlack, G. M., “ IonExchange Extraction, Separation and Radiochemical Determination of Neptunium-237 in Plutonium-238,” Analytica Chemica Acta, 48, 1969, pp. 233-241.C1475 05 (2010)12mL/min for the rinse solutions. A
37、lternately, follow the manu-facturers recommendations.8. Precautions8.1 Refer to the laboratorys chemical hygiene plan andother applicable guidance for handling chemical and radioac-tive materials and for the management of radioactive, mixed,and hazardous waste.8.2 Hydrofluoric acid is a highly corr
38、osive 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. Hydrofluoric acid differsfrom other acids because the fluoride
39、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 hydrofluoric acid burns, prevention ofexposure or injury of per
40、sonnel is the primary goal. Utilizationof appropriate laboratory controls (hoods) and wearing ad-equate personal protective equipment to protect from skin andeye contact is essential.9. Sampling9.1 Collect the sample in accordance with Practice C998.9.2 Prepare the sample for analysis in accordance
41、withPractice C999.10. Sample Solubilization10.1 Weigh 10.0 g of dried and prepared soil and addneptunium-239 yield monitor in either a separated form or insecular equilibrium with americium-243. As indicated in 7.12,either beta counting using Test Method D1890 or gamma-rayspectrometry using Practice
42、 D4962 may be utilized for count-ing the neptunium-239 yield monitor. The amount ofneptunium-239 yield monitor activity utilized is dependent onthe selected counting technique, the efficiency of the countingtechnique, and the desired counting duration. Obtaining ap-proximately 10 000 net counts from
43、 neptunium-239 by what-ever counting technique is used will produce a Poissoncounting uncertainty of about 1 % at one standard deviation.Given the short half-life of neptunium-239, delay in itscounting will reduce the number of counts obtained withresulting increase in counting uncertainty.10.2 A nu
44、mber of methods are available to solubilize soilsamples to prepare them for radiochemical analysis. Threefrequently used techniques are acid leaching, fusion, andmicrowave digestion. Leaching procedures are described inTest Methods C1000 and C1001. A general overview of allthree methods is provided
45、in Guide C1387 along with refer-ences to detailed procedures. Other methods include proce-dures for dissolution of silicates or acid-resistant matrixsamples in Practice C1317, dissolution of solid samples byfusion in Practice C1342, and the microwave dissolution ofglass in Practice C1412. The choice
46、 of specific dissolutionmethod is left to the laboratory conducting this analysis.11. Procedure11.1 Prepare any blanks, spikes, duplicates, or othersamples required by the laboratory protocols as part of thisanalysis in accordance with 10.2.11.2 All undigested solids should be removed by filtrationo
47、r centrifugation prior to performing this purification proce-dure. Evaporate the samples to near dryness on a hot plate setat 110C.11.3 Remove the sample beakers from the hot plate andallow them to cool to room temperature.11.4 Add 5 mL of 2.5 M HNO3-0.5 M Al(NO3)3to eachbeaker and swirl to dissolve
48、 the residue.11.5 Add 0.4 mLof 1.0 M ferrous sulfamate solution to eachbeaker.11.6 Add 0.5 mL of 3.0 M sodium nitrite to each samplebeaker.711.7 Allow the samples to sit at room temperature for 30 to40 min. The sample beakers should be swirled occasionally tofacilitate the reaction.811.8 During the
49、30-min incubation period, prepare theextraction chromatography columns.11.9 For prepackaged columns, break off the tip and allowthe water to drip through into an appropriate waste container.11.10 For either column type, condition the columns byadding 5 mL of 3.0 M nitric acid. Collect the column wash aswaste.11.11 After the samples have reacted for 30 to 40 min,8loadthe samples on the columns using disposable transfer pipettes.Collect the effluent as waste.11.12 Rinse the sample beaker with 5 mL of 3.0 M nitricacid, pass this rinse through the column, and coll
