1、Designation: C1475 05 (Reapproved 2010)1C1475 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 re
2、vision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1 NOTEEditorial changes were made throughout in June 2010.1. Scope1.1 This guide covers the determination of neptunium-237 in soil by mea
3、ns of radiochemical separations and alphaspectrometry. This guide provides options in the selection of sample preparation, separation, and measurement. Althoughneptunium-237 is not a component of global fallout, it is a product of production reactors and spent fuel processing. This guideis designed
4、for analysis of ten grams of soil previously collected and treated in accordance with Practices C998 and C999.Larger-size samples of environmental soil may also be analyzed, as long as the concentrations of interferences such as uraniumand thorium are at or near environmental concentrations. Dependi
5、ng on the choice of a sample dissolution method, all chemicalforms of neptunium may not be completely solubilized. This guide should allow the determination of neptunium-237concentrations from sub becquerel per gram levels to applicable standards depending on count time, sample size, detectorefficie
6、ncy, background, and tracer yield.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the us
7、er of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. Specific precautionary statements are given in Section 89.1.4 This international standard was developed in accordance with internationally recognized princi
8、ples on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclea
9、r MaterialsC998 Practice for Sampling Surface Soil for RadionuclidesC999 Practice for Soil Sample Preparation for the Determination of RadionuclidesC1000 Test Method for Radiochemical Determination of Uranium Isotopes in Soil by Alpha SpectrometryC1001 Test Method for Radiochemical Determination of
10、Plutonium in Soil by Alpha SpectroscopyC1163 Practice for Mounting Actinides for Alpha Spectrometry Using Neodymium FluorideC1284 Practice for Electrodeposition of the Actinides for Alpha SpectrometryC1317 Practice for Dissolution of Silicate or Acid-Resistant Matrix Samples (Withdrawn 2001)3C1342 P
11、ractice for Flux Fusion Sample Dissolution (Withdrawn 2001)3C1387 Guide for the Determination of Technetium-99 in SoilC1412 Practice for Microwave Oven Dissolution of Glass Containing Radioactive and Mixed Wastes (Withdrawn 2001)3D1193 Specification for Reagent WaterD1890 Test Method for Beta Partic
12、le Radioactivity of WaterD3084 Practice for Alpha-Particle Spectrometry of WaterD4962 Practice for NaI(Tl) Gamma-Ray Spectrometry of Water1 This guide is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.Curr
13、ent edition approved June 1, 2010June 1, 2017. Published June 2010July 2017. Originally approved in 2000. Last previous edition approved in 20052010 asC1475 05.C1475 05 (2010)1. DOI: 10.1520/C1475-05R10E01.10.1520/C1475-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or conta
14、ctASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intende
15、d only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current
16、versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.2 Other Documents:IEEE/ASTM SI-10 Standard for the Use of the International System of Units (SI):
17、The Modern Metric System3. Terminology3.1 Except as otherwise defined herein, definitions of terms are as given in Terminology C859.4. Summary of Guide4.1 This guide may be used to determine neptunium-237 in soil at potential release sites. A neptunium-239 yield monitor isadded to the soil aliquot a
18、nd the sample solubilized by one of several methods, such as those described in Guide C1387. Theneptunium is separated from the resulting solution using an extraction chromatography column.Avalence adjustment is performedprior to loading the sample onto the conditioned chromatography column. The sam
19、ple is passed through the column, which retainsthe neptunium in the +4 oxidation state. The column is washed to remove interferences and selectively eluted with dilute acid. Thesamples are prepared for measurement by neodymium fluoride co-precipitation or electrodeposition, and the neptunium-237cont
20、ent determined by alpha spectrometry. The neptunium-239 yield monitor is determined by beta or gamma-ray counting.5. Significance and Use5.1 A soil sampling and analysis program provides a direct means of determining the concentration and distribution ofradionuclides in soil. The presence and extent
21、 of neptunium-237 is of particular interest because it is one of the more mobiletransuranics in terms of migration and plant uptake. Since soil is an integrator and a reservoir on long-lived radionuclides, andserves as an intermediary in several pathways of potential importance to humans, knowledge
22、of the concentration ofneptunium-237 in soil is essential.6. Interferences6.1 Phosphates present in the sample matrix will interfere with the separation chemistry.Aluminum nitrate may be added to theload solution to minimize this problem.6.2 High concentrations of uranium or thorium can overload the
23、 column, resulting in low recoveries of neptunium or spectralinterferences. A preliminary separation may be required to avoid spectral interference from uranium, see Test Method C1000. Thepresence of uranium-233 and uranium-234 could cause spectral interferences with the neptunium-237 determination.
24、7. Apparatus7.1 Apparatus for the sample dissolution and measurement are identified within the selected test method.7.2 Extraction Columns, with a bed volume of several millilitres for the extraction chromatography resin.48. Reagents8.1 Purity of ReagentsReagent grade chemicals shall be used in all
25、tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society wheresuch specifications are available.5 Other grades may be used, provided it is first ascertained that the reagent is of s
26、ufficiently highpurity to permit its use without lessening the accuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean reagent water as defined inSpecification D1193.8.3 Aluminum Nitrate Hydrate Al(NO3)39H2O.8.4 Aliphatic Quaternar
27、y Amine Extraction Chromatography Resin.48.5 Ferrous Sulfamate Fe(SO3NH2)2, 1.0MDissolve 38.8 g of sulfamic acid (NH2SO3H) and 11.6 g of iron powder inapproximately 150 mL of water. Stir while heating until dissolved and then dilute to 200 mL with water. Prepare fresh each weekor keep under a nitrog
28、en blanket to minimize oxidation.8.6 Hydrofluoric Acid (48 to 51 %)Concentrated hydrofluoric acid (HF).8.7 Iron Powder.8.8 Nitric Acid (sp gr 1.42)Concentrated nitric acid (HNO3).8.9 Nitric Acid, 3.0MAdd 189 mL of concentrated nitric acid to 400 mL of water and dilute to 1.0 L with water and mix.4 P
29、repacked columns of TEVA Resin from Eichrom Technologies, Inc., Lisle, IL, have been found to be satisfactory for this purpose.5 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe America
30、n Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.C1475 1728.10 2.5 M Nitric Acid-0.5 M Aluminum NitrateDissolve 187.6 g of aluminum nit
31、rate in about 500 mL of water, add 159 mLof concentrated nitric acid, and dilute to 1.0 L.8.11 0.02 M Nitric Acid-0.02 M Hydrofluoric AcidAdd 1.25 mL of concentrated nitric acid and 0.7 mL of concentratedhydrofluoric acid to 800 mL of water and dilute to 1.0 L with water and mix.8.12 Radiometric Yie
32、ld TracerNeptunium-239 is normally used as a yield monitor in the determination of neptunium-237.Where beta counting is used to determine the neptunium-239 yield, a relatively low amount of activity, for example, 5 to 15 Bq,is typically required to obtain the desired precision with a 60-min count du
33、ration. Another option is the addition of a knownquantity of americium-243, in secular equilibrium with neptunium-239, directly to the sample. This approach has the advantageof allowing the use of americium-243 solutions of NIST-traceable activity. Where gamma-ray counting is used to determine thene
34、ptunium-239 yield, a larger amount of activity, for example, 120 to 1200 Bq, may be required to obtain the desired precisionwith a 10-min count duration dependent on the use of a NaI(TI) or HPGe detector. In this situation, it may be preferred to obtainthe neptunium-239 from an americium-243 cow.6 T
35、his approach has the advantage of conserving the americium-243 parent withthe neptunium-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 in order to not adversely impact the precisi
36、on of the sample neptunium-237activity determination.8.13 Sodium Nitrite (NaNO2).8.14 Sodium Nitrite, 3.0MDissolve 2.1 g of sodium nitrite in 10 mL of water. Prepare fresh daily.8.15 If prepacked columns are not available, prepare the resin by combining it with an equal volume of water, mix well, an
37、dallow to settle overnight. Decant the supernatant water. Prepare a column for each sample by pouring resin into each column.Adjust the settled resin bed volume to approximately 2 mL. Prepare only enough resin that is needed for use each day.8.16 The use of dry-packed cartridges of the extraction ch
38、romatography resin in combination with a vacuum manifold systemhas been found acceptable. When using vacuum-assisted flow, it is essential to ensure that flow rates do not exceed 1 mL/min forload solutions and strip solutions, and 2 mL/min for the rinse solutions. Alternately, follow the manufacture
39、rs recommendations.9. Precautions9.1 Refer to the laboratorys chemical hygiene plan and other applicable guidance for handling chemical and radioactivematerials and for the management of radioactive, mixed, and hazardous waste.9.2 Hydrofluoric acid is a highly corrosive acid that can severely burn s
40、kin, eyes, and mucous membranes. Hydrofluoric acidis similar to other acids in that the initial extent of a burn depends on the concentration, the temperature, and the duration of contactwith the acid. Hydrofluoric acid differs from other acids because the fluoride ion readily penetrates the skin, c
41、ausing destructionof deep tissue layers. Unlike other acids that are rapidly neutralized, hydrofluoric acid reactions with tissue may continue for daysif left untreated. Due to the serious consequences of hydrofluoric acid burns, prevention of exposure or injury of personnel is theprimary goal. Util
42、ization of appropriate laboratory controls (hoods) and wearing adequate personal protective equipment to protectfrom skin and eye contact Familiarization and compliance with the Safety Data Sheet is essential.10. Sampling10.1 Collect the sample in accordance with Practice C998.10.2 Prepare the sampl
43、e for analysis in accordance with Practice C999.11. Sample Solubilization11.1 Weigh 10.0 g of dried and prepared soil and add neptunium-239 yield monitor in either a separated form or in secularequilibrium with americium-243. As indicated in 7.128.12, either beta counting using Test Method D1890 or
44、gamma-rayspectrometry using Practice D4962 may be utilized for counting the neptunium-239 yield monitor. The amount of neptunium-239yield monitor activity utilized is dependent on the selected counting technique, the efficiency of the counting technique, and thedesired counting duration. Obtaining a
45、pproximately 10 000 net counts from neptunium-239 by whatever counting technique isused will produce a Poisson counting uncertainty of about 1 % at one standard deviation. Given the short half-life ofneptunium-239, delay in its counting will reduce the number of counts obtained with resulting increa
46、se in counting uncertainty.11.2 A number of methods are available to solubilize soil samples to prepare them for radiochemical analysis. Three frequentlyused techniques are acid leaching, fusion, and microwave digestion. Leaching procedures are described in Test Methods C1000and C1001. A general ove
47、rview of all three methods is provided in Guide C1387 along with references to detailed procedures.Other methods include procedures for dissolution of silicates or acid-resistant matrix samples in Practice C1317, dissolution of6 Information on the generation and use of americium-243 cows to obtain n
48、eptunium-239 can be obtained from: Garraway, J., and Wilson, P. D., “Preparation of Np-239by Separation from the Parent Am-243,” Journal of the Less-Common Metals, 91, 1983, L13-L16, and Bubernak, J., Lew, M. S., and Matlack, G. M., “Ion ExchangeExtraction, Separation and Radiochemical Determination
49、 of Neptunium-237 in Plutonium-238,” Analytica Chemica Acta, 48, 1969, pp. 233-241.C1475 173solid samples by fusion in Practice C1342, and the microwave dissolution of glass in Practice C1412. The choice of specificdissolution method is left to the laboratory conducting this analysis.12. Procedure12.1 Prepare any blanks, spikes, duplicates, or other samples required by the laboratory protocols as part of this analysis inaccordance with 10.211.2.12.2 All undigested solids should be removed by filtration or centrifugation prior to performing this purificat
