1、Designation: C1816 15Standard Practice forThe Ion Exchange Separation of Small Volume SamplesContaining Uranium, Americium, and Plutonium Prior toIsotopic Abundance and Content Analysis1This standard is issued under the fixed designation C1816; the number immediately following the designation indica
2、tes the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice is an alternative to Practice
3、C1411 for theion exchange separation in small mass samples (5 g ofplutonium and up to 0.5 mg of uranium in 1 mL of solution) ofuranium and plutonium from each other and from otherimpurities for subsequent isotopic abundance and contentanalysis by thermal ionization mass spectrometry (TIMS). Inadditi
4、on to being adapted to smaller sample sizes, this practicealso avoids the use of hydrochloric acid (HCl) and hydrofluoricacid (HF) and does not require the use of two anion exchangecolumns as required in Practice C1411.1.2 In chemically unseparated samples isobaric nuclides atmass 238 (238U and238Pu
5、), and mass 241 (241Pu and241Am)will be measured together thus compromising the accuracy ofthe results of isotopic composition of Pu. Therefore, chemicalseparation of elements is essential prior to isotopic analyses.Concentrations and volumes given in the paragraphs below canbe modified for larger s
6、ample sizes, different types of anionexchange resin, etc.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresp
7、onsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C698 Test Methods for Chemical, Mass Spectrometric, andSpectrochemical Analysis of Nuclear-
8、Grade Mixed Ox-ides (U, Pu)O2)C833 Specification for Sintered (Uranium-Plutonium) Diox-ide PelletsC859 Terminology Relating to Nuclear MaterialsC1008 Specification for Sintered (Uranium-Plutonium)DioxidePelletsFast Reactor Fuel (Withdrawn 2014)3C1168 Practice for Preparation and Dissolution of Pluto
9、niumMaterials for AnalysisC1347 Practice for Preparation and Dissolution of UraniumMaterials for AnalysisC1411 Practice for The Ion Exchange Separation of Ura-nium and Plutonium Prior to Isotopic AnalysisC1415 Test Method for238Pu Isotopic Abundance By AlphaSpectrometryC1625 Test Method for Uranium
10、and Plutonium Concentra-tions and Isotopic Abundances by Thermal IonizationMass SpectrometryC1672 Test Method for Determination of Uranium or Pluto-nium Isotopic Composition or Concentration by the TotalEvaporation Method Using a Thermal Ionization MassSpectrometerD1193 Specification for Reagent Wat
11、er3. Terminology3.1 DefinitionsFor definitions of terms used in thispractice, refer to Terminology C859.4. Summary of Practice4.1 Solid samples are dissolved according to PracticesC1168 or C1347 or other appropriate methods. The resultingsolution is processed by this practice to prepare separatesolu
12、tions of plutonium and uranium for mass spectrometricisotopic abundance analysis using Test Method C698, C1625,or C1672.Appropriate portions are taken to provide up to 5 gof plutonium on the ion exchange column to be separated from0.5 mg or less of uranium.All dilutions should be performed bymass to
13、 ensure the smallest uncertainty possible. This practice1This practice is under the jurisdiction of ASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved June 1, 2015. Published July 2015. DOI: 10.1520/C1816-15.2For
14、 referenced 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.3The last approved version of this historical standard is referen
15、ced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1can be used for higher uranium to plutonium ratios, but columnrinsing volumes should be adjusted accordingly (see 10.1.3.8).Using the volumes proposed in this practice
16、 leads to aseparation efficiency of at least 99.999 % between uranium andplutonium. Valence adjustment is obtained by using the proce-dure described in 4.1.1 or by an alternative method demon-strated by the user to perform the equivalent reduction/oxidation procedure.4.1.1 For any sample type, espec
17、ially those containing largeamounts of impurities, ferrous sulfate may be used for reduc-tion. The sample is diluted in 1 M nitric acid (HNO3). Ferroussulfate is added to reduce all plutonium to plutonium (III), then0.7 M sodium nitrite (NaNO2) is added to oxidize plutonium(III) to plutonium (IV).4.
18、2 After oxidation state adjustment, the resulting solutionis passed through an anion exchange column in the nitrateform, which retains negatively-charged complexes of Pu(IV),U(VI), U(IV), etc. The process of complex formation andsorption in solutions of HNO3for Pu and U may be writtendown in a simpl
19、ified manner as follows:Pu4116NO32Pu NO3!6#22Pu NO3!6#2212NO325!Pu NO3!6#225!12NO32UO2!2114NO32UO2!NO3!4#22UO2!NO3!4#2212NO325!UO2!NO3!4#225!12NO32As the nitrate concentration increases, the concentration ofthe hexanitrate complex increases and the maximum adsorp-tion is attained at an acidity of ab
20、out 7.7 M.The adsorbed plutonium is washed with 7-8 M HNO3toremove americium and other impurities that are not adsorbed,and then washed with 3-4 M HNO3to remove uranium. Theuranium is recovered and then the column is rinsed with a largevolume of 3-4 M HNO3to remove the residual uranium. Twomechanism
21、s are used in the desorption of tetravalent plutoniumfrom the anion exchanger. One is to shift the complexformation equilibrium by decreasing the concentration ofnitrate ions in the eluent. The second mechanism consists ofreducing Pu(IV) to Pu(III) by addition of the reducing agenthydroxylammonium n
22、itrate (NH3OHNO3). The plutonium isstripped from the column with a solution of 0.2 to 0.35 MHNO3and 1.9E-02 M hydroxylammonium nitrate(NH3OHNO3). The volume of the eluting solution needed issmaller compared to using only 0.2 to 0.35 M HNO3, and thesolution obtained after purification is more concent
23、rated.5. Significance and Use5.1 Uranium and plutonium are used in nuclear reactor fueland must be analyzed to ensure that they meet acceptancecriteria for isotopic composition as described in SpecificationsC833 and C1008. The criteria are set by mutual agreementbetween the manufacturer and end user
24、 (or between buyer andseller).This standard practice is used to separate chemically theisobaric interferences from238U and238Pu and from241Am and241Pu, and from other impurities prior to isotopic abundancedetermination by TIMS.5.2 In facilities where perchloric acid use is authorized, theseparation
25、in Test Method C698 may be used prior to isotopicabundance determination. Uranium and plutonium content aswell as isotopic abundances using TIMS can be determined byusing this separation practice and by following Test MethodsC698, C1625,orC1672.6. Mass Spectrometry Interferences Resolved by thisSepa
26、ration Practice6.1 The separated heavy element fractions placed on massspectrometric filaments must be pure. The quantity requireddepends upon the sensitivity of the instrument detectionsystem. Chemical purity of the sample becomes more impor-tant as the sample size decreases, because the ion emissi
27、on ofthe sample is repressed by impurities.6.2 Organic compounds from the degradation of ion ex-change resin, if present, could affect the response of the massspectrometer during the plutonium and uranium isotopic abun-dance measurements. Evaporation of the samples in concen-trated HNO3after the ion
28、 exchange separation will destroyresin degradation products.NOTE 1The sample should not be evaporated using heat aboveapproximately 170C to avoid oxide formation that will make re-dissolving the sample difficult.6.3 Elemental impurities, especially alkali elements, tend toproduce unstable ion emissi
29、on that alter the observed pluto-nium and uranium isotope ratios in an unpredictable manner.6.4 Isobaric impurities or contaminants will alter the ob-served isotope ratios; most notable of these for plutonium are241Am and238U; the most notable isobaric impurity foruranium is238Pu.6.5 Extreme care mu
30、st be taken to avoid contamination ofthe sample by environmental uranium. The level of uraniumcontamination should be measured by analyzing an aliquant of8 M HNO3reagent as a blank taken through the same chemicalprocessing as the sample, including the addition of233U, andcomputing the amount of uran
31、ium it contains.7. Apparatus7.1 Polyethylene Ion Exchange ColumnsDisposable, 0.9cmid3cmwith a 15-mL reservoir (or other column withsufficient volume for operation).7.2 Laboratory BalancePrecision 60.1 mg.7.3 Beakers or Alternate Acceptable ContainersPretreated, 10-30 mL, borosilicate glass. To avoid
32、 crosscontamination, use only new borosilicate glass containers.Depending on the need, containers can be pretreated by heatingin 4 M HNO3to leach uranium, and then rinsed in deionizedwater, and air or oven dried prior to use.7.4 Infrared Heating Lamps or Hot Plate with adjustablelow and high heat se
33、ttings.7.5 Transfer PipetsDisposable.8. Reagents8.1 Reagent grade or better chemicals should be used.Unless otherwise indicated, it is intended that all reagentsconform to the specifications of the Committee on AnalyticalC1816 152Reagents of the American Chemical Society4where suchspecifications are
34、 available. Other grades of reagents may beused, provided it is first ascertained that the reagent is ofsufficient purity to permit its use without lessening the accu-racy of measurements made on the prepared materials. Storesolutions in appropriate polyethylene or glass bottles except asnoted.8.2 W
35、aterUnless otherwise indicated, references to watershall be understood to mean laboratory accepted demineralizedor deionized water in conformance with Specification D1193,Type 1.8.3 Nitric Acid, 70.4 w/w%concentrated HNO3.8.4 Nitric Acid, 7.5 to 8 MAdd 490 6 15 mL of HNO3(70.4 w/w%) to about 400 mL
36、of water and dilute to 1 L.8.5 Nitric Acid, 3.4 to 4 MAdd 234 6 20 mL of HNO3(70.4 w/w%) to about 700 mL of water and dilute to 1 L withwater.8.6 Nitric Acid, 1 MAdd 63 mL of HNO3(70.4 w/w%)toabout 750 mL of water and dilute to 1 L with water.8.7 Nitric Acid, 0.3 MAdd 19 mL of HNO3(70.4 w/w%)to abou
37、t 750 mL of water and dilute to 1 L with water.8.8 Crystallized Sodium Nitrite (ACS grade)NaNO2.8.9 Crystallized Ferrous Sulfate Heptahydrate (ACSgrade)FeSO4,7H2O.8.10 Sulfuric Acid, 18 MConcentrated H2SO4(sp gr1.84).8.11 Sulfuric Acid, 0.1 MAdd 5.6 mL of H2SO4(sp gr1.84) to about 750 mL of water an
38、d dilute to 1 L with water.8.12 Hydroxylammonium nitrate (HAN) (sp gr 1.18), 24wt.% in H2OHydroxylammonium nitrate (NH3OHNO3) 2.95M.8.13 Crystallized Sodium Nitrate (ACS grade)NaNO3.8.14 Sodium Nitrate, 1 MAdd 85 g of NaNO3to about750 mL of water, agitate until the sodium nitrate is completelydissol
39、ved and then dilute to 1 L with water.8.15 Anion Exchange Resin1 4 100 200 mesh, dryresin, conditioned in8MHNO3to achieve 50 100 mesh, wetresin. (WarningNever allow anion exchange resin condi-tioned in strong concentrations of acid with HAN to dry, asammonium nitrate (NH4NO3) can form and cause anex
40、plosion risk. Additionally, nitrate form anion resin andstrong concentrations of HNO3can undergo a chemicalreaction under certain conditions and can self-heat andundergo an autocatalytic reaction. To avoid these hazardsensure that the resin is rinsed with a solution capable ofremoving the nitrate fr
41、om the resin, for example 0.5 MHNO3.)8.16 Preparation of the HAN Stripping Solution (0.3 MHNO3, 1.9E-02 M HAN)Add 320 L of hydroxylammoniumnitrate to 50 mL of 0.3 M HNO3.8.17 Preparation of Oxidation Solution (0.7 M NaNO2inH2OAdd 1.2 g of NaNO2,H2O (ACS grade) to a 20-mLvolumetric flask and dilute t
42、o the mark with water. Cap theflask and agitate until the sodium nitrite is dissolved com-pletely.NOTE 2The oxidation solution is not stable for long periods of timeand should be used within 8 hours of preparation.8.18 Preparation of Reduction Solution (0.3 M FeSO4, 0.1MH2SO4Add 1.67 g of FeSO4,7H2O
43、 to a 20-mL volumetricflask and dilute to the mark with 0.1 MH2SO4. Cap the flaskand agitate until the ferrous sulfate heptahydrate is dissolvedcompletely.NOTE 3The reduction solution is not stable for long periods of timeand should be used within 8 hours of preparation.8.19 Preparation of the Anion
44、 Exchange ResinIf the resinis conditioned in a non-nitrate form, such as chloride, it mustbe conditioned in a nitrate form before use. Also, in order forthe separation to be effective, the resin must be conditioned at8MHNO3. Many methods are appropriate, and exactpreparation can depend on the resin
45、manufacturer, but ingeneral the conditioning must allow for the removal of mostnon-nitrate ions from the resin without causing damage to theresin (some residual chloride ions may still be present afterconditioning the resin, but should not affect the separation).Two example methods appropriate for u
46、se with a resin condi-tioned in chloride form are presented below.8.19.1 Example 1: Resin Chloride to Nitrate Conversionand Conditioning at 8 M HNO3in a Beaker:8.19.1.1 Place 250 g of resin conditioned in chloride forminto a 5-L beaker.8.19.1.2 Add 2 L of deionized water to the beaker andagitate the
47、 mixture for 1.5 hours.8.19.1.3 Let the resin solution settle for 2 hours and thendecant the supernatant.8.19.1.4 Repeat steps 8.19.1.2 to 8.19.1.3 at least twoadditional times (a total of 6 L deionized water) or until theaddition of silver nitrate to the decanted supernatant reveals nosilver chlori
48、de precipitate.8.19.1.5 Add 2 L of 0.3 M HNO3from 8.7 to the beakerand agitate the mixture for 1.5 hours.8.19.1.6 Let the resin solution settle for 2 hours and thendecant the supernatant.8.19.1.7 Repeat steps 8.19.1.5 to 8.19.1.6 one additionaltime (a total of 4 L 0.3 M HNO3).8.19.1.8 Add 2 Lof 3.4
49、to 4 M HNO3from 8.5 to the beakerand agitate the mixture for 1.5 hours.8.19.1.9 Let the resin solution settle for 2 hours and thendecant the supernatant.8.19.1.10 Repeat steps 8.19.1.8 to 8.19.1.9 one additionaltime (a total of 4 L 3.4 to 4 M HNO3).8.19.1.11 Add 2 L of 7.5 to 8 M HNO3from 8.4 to thebeaker and agitate the mixture for 1.5 hours.8.19.1.12 Let the resin solution settle for 2 hours and thendecant the supernatant.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Wash
