1、Designation: C 1307 02Standard Test Method forPlutonium Assay by Plutonium (III) Diode ArraySpectrophotometry1This standard is issued under the fixed designation C 1307; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes the determination of totalplutonium as plutonium(III) in nitrate and chloride solutions.The
3、 technique is applicable to solutions of plutonium dioxidepowders and pellets (Test Methods C 697), nuclear grademixed oxides (Test Methods C 698), plutonium metal (TestMethods C 758), and plutonium nitrate solutions (Test Meth-ods C 759). Solid samples are dissolved using the appropriatedissolution
4、 techniques described in Practice C 1168. The use ofthis technique for other plutonium-bearing materials has beenreported (1-5), but final determination of applicability must bemade by the user. The applicable concentration range forplutonium sample solutions is 10200 g Pu/L.21.2 This standard does
5、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 applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standa
6、rds:C 697 Test Methods for Chemical, Mass Spectrometric, andSpectrochemical Analysis of Nuclear-Grade PlutoniumDioxide Powders and Pellets3C 698 Test Methods for Chemical, Mass Spectrometric, andSpectrochemical Analysis of Nuclear-Grade Mixed Oxides(U, Pu)O2)3C 757 Specification for Nuclear-Grade Pl
7、utonium DioxidePowder, Sinterable3C 758 Test Methods for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and Radiochemical Analysis ofNuclear-Grade Plutonium Metal3C 759 Test Methods for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and Radiochemical Analysis ofNuclear-Grade Plutoniu
8、m Nitrate Solutions3C 833 Specification for Sintered (Uranium-Plutonium) Di-oxide Pellets3C 1168 Practice for Preparation and Dissolution of Pluto-nium Materials for Analysis33. Summary of Method3.1 In a diode array spectrophotometric measurement, as ina conventional spectrophotometric measurement,
9、the substancebeing determined absorbs light at frequencies characteristic ofthat substance. The amount of light absorbed at each wave-length is directly proportional to the concentration of thespecies of interest. The absorption is a function of the oxidationstate and the complexation obtained in th
10、e solution matrixselected for measurement. Beers Law permits quantifying thespecies of interest relative to a traceable standard when bothsolutions are measured under the same conditions. The array ofphotosensitive diodes permits the (virtually) simultaneouscollection of spectral information over th
11、e entire range of theinstrument, for example, 190820 nm (or any selected portionof the range). An entire absorption spectrum can be obtained in0.1 s; however, optimum precision is obtained from multiplespectra collected over a 4-s period.3.2 Reduction to plutonium(III) is accomplished by theaddition
12、 of a measured quantity of reductant solution to thesample aliquant.3.2.1 For nitrate solutions, ferrous sulfamate is the recom-mended reductant. Aliquants (1 mL or less) of the samplesolution are diluted with 10 mL of a ferrous reductant/matrixsolution to 1 g Pu/L, and measured.3.2.2 For chloride s
13、olutions, ascorbic acid is the recom-mended reductant. Aliquants of the sample solution, eachcontaining 50100 mg of plutonium, are diluted with 2 mL ofzirconium solution to complex fluoride ions, 2 mL ascorbicacid reductant solution, and 1.0 M HCl to a total volume of 25mL, yielding 24 g Pu/L soluti
14、ons for measurement.3.3 Plutonium concentration is determined from light ab-sorption measurements taken on the sample solution in theblue-green region from 516 to 640 nm where a broad doubletband is observed. Spectral quantifying software capable offitting the sample spectrum with spectral informati
15、on fromstandard solutions is used to calculate the plutonium concen-tration. Both commercially available (6) and custom-designed1This test method is under the jurisdiction of ASTM Committee C-26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current ed
16、ition approved Jan. 10, 2002. Published May 2002. Originallypublished as C130795. Last previous edition C130795.2For solid samples, select the sample size and dissolved solution weight to yieldsample solutions in the 1030 g Pu/L range. With special preparation and spectralanalysis techniques, the me
17、thod has been applied to nitrate solutions in the 0.110g Pu/L range.3Annual Book of ASTM Standards, Vol 12.01.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.(7-12) spectral fitting software have been developed whichmay be used for p
18、lutonium measurements. The users of thisprocedure are responsible for selecting or customizing, or both,the spectral fitting (and instrument control) software that bestmeets their individual measurement methodology and needs.Software selection will dictate many of the procedural specificsnot include
19、d in this procedure. This procedure is intended toaddress key measurement requirements and to allow usersdiscretion in establishing appropriate procedural details andtechnique variations. The software package selected shouldinclude a feature that indicates the quality of spectral fit,thereby providi
20、ng information on the measurement reliabilityand the presence of interferences that absorb light or otherwisealter the plutonium(III) spectrum without requiring supplemen-tal measurements.4. Significance and Use4.1 This test method is designed to determine whether agiven material meets the purchaser
21、s specification for pluto-nium content.5. Interferences5.1 Materials meeting the applicable material specificationsof the ASTM standard for which this procedure was developed,when dissolved and diluted without introduction of interferingcontaminants as described in Practice C 1168, will contain noin
22、terfering elements or species.NOTE 1Fluoride, if present, would interfere if the zirconium, rou-tinely added to the sample solution aliquant for the chloride matrix, wereomitted from the procedure. Zirconium may be added to the nitrate matrix.Ferrous-Reductant Solution to handle fluorides if present
23、. Zirconium,when used, should be added to all samples, blanks, and standards to obtaina consistent matrix. Refer to Specifications C 833 and C 757.5.2 Interferences are caused by: 1) materials that absorblight in the region of the plutonium absorption, 2) undissolvedsolids that cause light scatterin
24、g, 3) strong oxidizing orcomplexing agents that prevent complete reduction of theplutonium to the plutonium(III) oxidation state, and 4) anionsthat shift the spectrum.5.2.1 Absorption of light in the region of interest by anotherspecies is a potential interference. Identification of potentiallyinter
25、fering species and inclusion of their spectra in the spectralcurve fitting process will significantly reduce their effect. At aminimum, sample measurements should be flagged when thehigher than normal fitting error occurs, , resulting from thepresence of unidentified absorbing species. Enhancement o
26、fthe spectral curve fitting capabilities of the DAS can beachieved by taking double derivatives of the spectrum col-lected. The spectral curve fitting software of the DAS is thenused to quantitate the mathematically manipulated spectrum.NOTE 2Care must be taken in the choice of the preprocessingmeth
27、ods (derivatives, mean centering, autoscaling and/or channel selec-tion) as these may affect the robustness of the final model, particularlywith regard to unknown interferences. Use of residual analysis will notalways detect unknown intereferences and results will vary depending onthe preprocessing
28、methods and models employed.5.2.2 This spectrophotometric assay method should not beused on turbid (cloudy) solutions or solutions containingundissolved material. In addition to visual or turbidity metermeasurements, or both, the presence of undissolved solids maybe identified by the resulting shift
29、s in the spectral baseline andby elevated spectral fitting errors.NOTE 3Plutonium oxides, mixed oxides, and plutonium metals meet-ing the material specifications for which this test method is intended, willdissolve when procedures in Practice C 1168 are followed. Failure toachieve dissolution is an
30、indication that the material does not meet thespecifications, and the application of this test method for plutonium assaymust be verified by the user. The user and customer are cautioned: whenundissolved solids that persist after exhaustive dissolution efforts are to beremoved by filtration through
31、filter paper or other inert material ofappropriate porosity, the subsequent plutonium assay measurementsrequire close scrutiny. While filtration of undissolved solids may permitthe reliable measurement of the concentration of plutonium in the filtrate,the resulting analysis may not be representative
32、 of their source material.Solids may indicate incomplete dissolution of the plutonium in the samplematerial, not necessarily a plutonium-free refractory residue. When thistechnique is utilized in support of reprocessing operations, processsolutions containing solids may be an indication of incomplet
33、e dissolutionof the plutonium-bearing material being processed or of an error inprocess operations. In addition to process control considerations, theundissolved solids may represent accountability and criticality controlproblems.5.2.3 Strong oxidizing agents and complexing agents insufficient conce
34、ntration to prevent complete reduction typicallyare not present in plutonium nitrate samples. Appreciableconcentrations of fluoride and sulfate anions have been foundto interfere. The concentration of hydrofluoric acid, added tocatalyze dissolution of oxides, may be removed by evaporationprior to me
35、asurement to ensure that the zirconium effectivelycomplexes the traces of fluoride ion. Changes in the plutoniumspectrum from incomplete reduction due to oxidizing agentsand shifts in the spectrum due to complexing agents are alsoindicated by increases in the spectral curve fitting error.5.2.4 Anion
36、 identity and concentration will shift the loca-tion and alter the shape of the absorption curve. The systemcalibration must include the anion shift effect by encompassingthe expected range of anion identities and concentrations or byusing appropriate spectral fitting features that identify andcorre
37、ct for the effect.5.3 A study was conducted at the Los Alamos NationalLaboratory to determine the immunity of the Pu(III) spectro-photometric assay method to a diverse species of potentialinterferences. The elements studied were element numbers 1,9, 1113, 17, 19, 2231, 35, 42, 4446, 48, 50, 53, 57,
38、58, 60,62, 73, 74, 76, 77, 79, 83, 90, 92, 93, and 95. Potentialinterference from nitrate, phosphate, sulfate, and oxalic acid isalso documented (13).6. Apparatus6.1 Diode Array Spectrophotometer (DAS)wavelengthrange 190820 nm; wavelength accuracy6 2 nm; wavelengthreproducibility 60.05 nm; full dyna
39、mic range 0.0022 to 3.3;photometric accuracy at 1 AU with a NBS 931 filter at 512 nmis 60.005 AU; baseline flatness 0.0013 AU; noise at 500 nmis 0.0002 AU RMS; stray light measured with a Hoya 056 filterC 13072at 220 nm 0.05 %;46.2 Analytical Balancereadability of 0.1 mg; linearity 0.1mg over any 10
40、 g range and 0.2 mg over 160 g full scale.6.3 Solution Density Meterreadability of 0.1 mg/mL;precision of 0.3 mg/mL; linearity and accuracy 0.5 mg/mLover the range 0 to 2.0 g/mL.6.4 Adjustable, Fixed-Volume Pipetterscalibrated to de-liver the desired range of volumes for sample and matrix-reductant
41、solutions.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are a
42、vailable.5Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean distilled or deionized
43、water.7.3 Ascorbic Acid-Reductant Solution (C6H8O6, ami-noguanidine bicarbonate (CH6N4H2CO3), 0.4 M in eachreagent)Prepare fresh daily by dissolving7gofascorbicacid and 5.5 g aminoguanidine bicarbonate in 80 mL of 1 MHCl, then dilute to a final volume of 100-mL 1 M HCl.NOTE 4The ascorbic acid is sta
44、bilized by the addition of aminoguani-dine (Guanylhydrazine:HN:C(NH2)NHNH2). The stabilized reductantsolution has been found to be effective when ascorbic acid stabilityproblems are encountered.7.4 Ferrous-Reductant Solution (ferrous sulfamate, 0.05 M;sulfamic acid, 0.25 M; nitric acid, 1.0 M)Prepar
45、e freshweekly by adding 12 mL of freshly prepared ferrous sulfamate(2 M) to 90 mL of sulfamic acid (1.5 M). Stir, then add 175 mLof nitric acid (3.0 M) and dilute to 500 mL with water.7.5 Ferrous Sulfamate (Fe(NH2SO3)2, 2.0 M)Preparefresh for the preparation of the ferrous-reductant solution. Add220
46、 g of solid sulfamic acid to 450 mL of water, stir, and heatat 7080C until dissolved. Continue stirring and heating,while adding approximately 0.5-g portions of iron metalpowder (Fe0) until 56 g of iron have been dissolved in theheated sulfamic acid. Filter the solution while hot; allow tocool; then
47、 dilute to a final volume of 50 mL.NOTE 5The dissolution of the sulfamic acid need not be quantitativebefore beginning the addition of the iron powder. Excessive heatingbeyond the time required to achieve the dissolution of the sulfamicacid/iron powder or at temperatures above 80C will cause excessi
48、vedecomposition of the sulfamic acid7.6 Hydrochloric Acid (HCl, 12 M)Concentrated, sp gr1.19.7.7 Hydrochloric Acid (HCl, 1.0 M)Add 84 mL of hy-drochloric acid (sp gr 1.19) to approximately 500 mL of water.Stir, then dilute to a final volume of 1 L.7.8 Nitric Acid (HNO3, 15.8 M)Concentrated, sp gr 1.
49、42.7.9 Nitric Acid (1.0 M)Add 63 mL of nitric acid (sp gr1.42) to approximately 500 mL of water. Stir, then dilute to afinal volume of 1 L.7.10 Nitric Acid (3.0 M)Add 190 mL of nitric acid (sp gr1.42) to approximately 500 mL of water. Stir, then dilute to afinal volume of 1 L.7.11 Plutonium Standard SolutionsPrepare standardstraceable to a national measurement system, which cover therange of concentrations over which sample measurements willbe performed.7.12 Sulfamic Acid (NH2SO3H, 1.5 M)Dissolve 145 g ofsolid sulfamic acid in 900 mL of water with st
