1、Designation: C1475 17Standard 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. A number in parenth
2、eses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers the determination of neptunium-237in soil by means of radiochemical separations and alphaspectrometry. This guide provides options in
3、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 of ten grams of soil previouslycollected and treated in accordance with Pra
4、ctices 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 choice of a sample dissolution method,all chemical forms of neptunium may not b
5、e 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, and tracer yield.1.2 The values stated in SI units are to be regarded asst
6、andard. 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 standard to establish appro-priate safety and health practices and determine the ap
7、plica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 9.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of I
8、nternational Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclear MaterialsC998 Practice for Sampling Surface Soil for RadionuclidesC999 Practice for So
9、il 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 SpectroscopyC1163 Practice for Mounting Actinides for Alpha Sp
10、ectrom-etry Using Neodymium FluorideC1284 Practice for Electrodeposition of the Actinides forAlpha SpectrometryC1317 Practice for Dissolution of Silicate or Acid-ResistantMatrix Samples (Withdrawn 2001)3C1342 Practice for Flux Fusion Sample Dissolution (With-drawn 2001)3C1387 Guide for the Determina
11、tion of Technetium-99 inSoilC1412 Practice for Microwave Oven Dissolution of GlassContaining Radioactive and Mixed Wastes (Withdrawn2001)3D1193 Specification for Reagent WaterD1890 Test Method for Beta Particle Radioactivity of WaterD3084 Practice for Alpha-Particle Spectrometry of WaterD4962 Practi
12、ce 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 System1This guide is under the jurisdiction of ASTM Committee C26 on Nuclear FuelCycle and is the direct responsibility of Subcommittee C2
13、6.05 on Methods of Test.Current edition approved June 1, 2017. Published July 2017. Originally approvedin 2000. Last previous edition approved in 2010 as C1475 05 (2010)1. DOI:10.1520/C1475-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at se
14、rviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
15、 PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organizatio
16、n Technical Barriers to Trade (TBT) Committee.13. Terminology3.1 Except as otherwise defined herein, definitions of termsare as given in Terminology C859.4. Summary of Guide4.1 This guide may be used to determine neptunium-237 insoil at potential release sites. A neptunium-239 yield monitor isadded
17、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 conditionedchromatogr
18、aphy 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 orelectrodeposition, and th
19、e neptunium-237 content determinedby alpha spectrometry. The neptunium-239 yield monitor isdetermined by beta or gamma-ray counting.5. Significance and Use5.1 A soil sampling and analysis program provides a directmeans of determining the concentration and distribution ofradionuclides in soil. The pr
20、esence and extent of neptunium-237 is of particular interest because it is one of the more mobiletransuranics in 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 hum
21、ans, knowledge of the concentration ofneptunium-237 in soil is essential.6. Interferences6.1 Phosphates present in the sample matrix will interferewith the separation chemistry. Aluminum nitrate may be addedto the load solution to minimize this problem.6.2 High concentrations of uranium or thorium c
22、an overloadthe column, resulting in low recoveries of neptunium orspectral interferences. A preliminary separation 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-237
23、determination.7. Apparatus7.1 Apparatus for the sample dissolution and measurementare identified within the selected test method.7.2 Extraction Columns, with a bed volume of severalmillilitres for the extraction chromatography resin.48. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beu
24、sed 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 Societywhere such specifications are available.5Other grades may beused, provided it is first ascertained that the reage
25、nt 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 to mean reagent water as definedin Specification D1193.8.3 Aluminum Nitrate Hydrate Al(NO3)39H2O.8.4 Aliphatic Q
26、uaternary Amine Extraction Chromatogra-phy Resin.48.5 Ferrous Sulfamate Fe(SO3NH2)2, 1.0 MDissolve38.8 g of sulfamic 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
27、a nitrogen blanket to minimizeoxidation.8.6 Hydrofluoric Acid (48 to 51 %)Concentrated hydro-fluoric acid (HF).8.7 Iron Powder.8.8 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).8.9 Nitric Acid, 3.0 MAdd 189 mL of concentrated nitricacid to 400 mL of water and dilute to 1.0 L with water and
28、mix.8.10 2.5 M Nitric Acid-0.5 M Aluminum NitrateDissolve187.6 g of aluminum nitrate in about 500 mL of water, add 159mL of concentrated nitric acid, and dilute to 1.0 L.8.11 0.02 M Nitric Acid-0.02 M Hydrofluoric AcidAdd1.25 mL of concentrated nitric acid and 0.7 mL of concentratedhydrofluoric acid
29、 to 800 mL of water and dilute to 1.0 L withwater and mix.8.12 Radiometric Yield TracerNeptunium-239 is normallyused as a yield monitor in the determination of neptunium-237.Where beta counting is used to determine the neptunium-239yield, a relatively low amount of activity, for example, 5 to 15Bq,
30、is typically required to obtain the desired precision with a60-min count duration. Another option is the addition of aknown quantity of americium-243, in secular equilibrium withneptunium-239, directly to the sample. This approach has theadvantage of allowing the use of americium-243 solutions ofNIS
31、T-traceable activity. Where gamma-ray counting is used todetermine the neptunium-239 yield, a larger amount of activity,for example, 120 to 1200 Bq, may be required to obtain thedesired precision with a 10-min count duration dependent onthe use of a NaI(TI) or HPGe detector. In this situation, it ma
32、y4Prepacked columns of TEVA Resin from Eichrom Technologies, Inc., Lisle, IL,have been found to be satisfactory for this purpose.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the America
33、n Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.C1475 172be preferred to obtain the neptunium-239 from an americium-243 cow.6This approa
34、ch has the advantage of conserving theamericium-243 parent with the neptunium-239 activity beingreplenished over time. However, it has the disadvantage thatthe neptunium-239 activity of the milked solution must bedetermined with high precision in order to not adversely impactthe precision of the sam
35、ple neptunium-237 activity determina-tion.8.13 Sodium Nitrite (NaNO2).8.14 Sodium Nitrite, 3.0 MDissolve 2.1 g of sodiumnitrite in 10 mL of water. Prepare fresh daily.8.15 If prepacked columns are not available, prepare theresin by combining it with an equal volume of water, mix well,and allow to se
36、ttle overnight. Decant the supernatant 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.8.16 The use of dry-packed cartridges of the extractionchromatography res
37、in in combination with a vacuum 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 2mL/min for the rinse solutions. Alternately, follow the manu-facturers recommendatio
38、ns.9. Precautions9.1 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.9.2 Hydrofluoric acid is a highly corrosive acid that canseverely burn skin, eyes, and mu
39、cous membranes. Hydroflu-oric acid differs from other acids because the fluoride ionreadily penetrates the skin, causing destruction of deep tissuelayers. Unlike other acids that are rapidly neutralized, hydro-fluoric acid reactions with tissue may continue for days if leftuntreated. Familiarization
40、 and compliance with the Safety DataSheet is essential.10. Sampling10.1 Collect the sample in accordance with Practice C998.10.2 Prepare the sample for analysis in accordance withPractice C999.11. Sample Solubilization11.1 Weigh 10.0 g of dried and prepared soil and addneptunium-239 yield monitor in
41、 either a separated form or insecular equilibrium with americium-243. As indicated in 8.12,either beta counting using Test Method D1890 or gamma-rayspectrometry using Practice D4962 may be utilized for count-ing the neptunium-239 yield monitor. The amount ofneptunium-239 yield monitor activity utili
42、zed is dependent onthe selected counting technique, the efficiency of the countingtechnique, and the desired counting duration. Obtaining ap-proximately 10 000 net counts from neptunium-239 by what-ever counting technique is used will produce a Poissoncounting uncertainty of about 1 % at one standar
43、d deviation.Given the short half-life of neptunium-239, delay in itscounting will reduce the number of counts obtained withresulting increase in counting uncertainty.11.2 A number of methods are available to solubilize soilsamples to prepare them for radiochemical analysis. Threefrequently used tech
44、niques are acid leaching, fusion, andmicrowave digestion. Leaching procedures are described inTest Methods C1000 and C1001. A general overview of allthree methods is provided in Guide C1387 along with refer-ences to detailed procedures. Other methods include proce-dures for dissolution of silicates
45、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 of specific dissolutionmethod is left to the laboratory conducting this analysis.12. Procedure12.1 Prepare any blanks, spike
46、s, duplicates, or othersamples required by the laboratory protocols as part of thisanalysis in accordance with 11.2.12.2 All undigested solids should be removed by filtrationor centrifugation prior to performing this purification proce-dure. Evaporate the samples to near dryness on a hot plate setat
47、 approximately 110C.12.3 Remove the sample beakers from the hot plate andallow them to cool to room temperature.12.4 Add 5 mL of 2.5 M HNO3-0.5 M Al(NO3)3to eachbeaker and swirl to dissolve the residue.12.5 Add 0.4 mLof 1.0 M ferrous sulfamate solution to eachbeaker.12.6 Add 0.5 mL of 3.0 M sodium n
48、itrite to each samplebeaker.712.7 Allow the samples to sit at room temperature for 30 to40 min. The sample beakers should be swirled occasionally tofacilitate the reaction.812.8 During the incubation period called for in 12.7, preparethe extraction chromatography columns.12.9 For prepackaged columns
49、, break off the tip and allowthe water to drip through into an appropriate waste container.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,” Journal 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. 233-241.7When the sodi
