1、Designation: C1168 15Standard Practice forPreparation and Dissolution of Plutonium Materials forAnalysis1This standard is issued under the fixed designation C1168; 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. Scope1.1 This practice is a compilation of dissolution techniquesfor plutonium materials that are applicable to the test methodsused f
3、or characterizing these materials. Dissolution treatmentsfor the major plutonium materials assayed for plutonium oranalyzed for other components are listed. Aliquots of thedissolved samples are dispensed on a weight basis when one ofthe analyses must be highly reliable, such as plutonium assay;other
4、wise they are dispensed on a volume basis.1.2 Procedures in this practice are intended for the dissolu-tion of plutonium metal, plutonium oxide, and uranium-plutonium mixed oxides. Aliquots of dissolved samples areanalyzed using test methods, such as those developed bySubcommittee C26.05 on Methods
5、of Test, to demonstratecompliance with applicable requirements. These may includeproduct specifications such as Specifications C757 and C833.1.3 One or more of the procedures in this practice may beapplicable to unique plutonium materials, such as alloys,compounds, and scrap materials. The user must
6、 determine theapplicability of this practice to such materials.1.4 The treatments, in order of presentation, are as follows:Procedure Number Procedure Title Section1 Dissolution of Plutonium Metal with Hydrochloric Acid at RoomTemperature92 Dissolution of Plutonium Metal with Hydrochloric Acid and H
7、eating 103 Dissolution of Plutonium Metal with Sulfuric Acid 114 Dissolution of Plutonium Oxide and Uranium-Plutonium MixedOxide by the Sealed-Reflux Technique125 Dissolution of Plutonium Oxide and Uranium-Plutonium MixedOxides by Sodium Bisulfate Fusion136 Dissolution of Uranium-Plutonium Mixed Oxi
8、des and Low-FiredPlutonium Oxide in Beakers147 Open-Vessel (with Reflux Condenser) Dissolution of PlutoniumOxide Powder158 Open-Vessel (with Reflux Condenser) Dissolution of Mixed OxidePowder169 Closed-Vessel Hot Block Dissolution of Plutonium Oxide Powder 1710 Open-Vessel (with Reflux Condenser) Di
9、ssolution of Mixed OxidePellets181This 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 Sept. 1, 2015. Published October 2015. Originallyapproved in 1990. Last previous edi
10、tion approved in 2008 as C1168 08. DOI:10.1520/C1168-15.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States11.5 The values stated in SI units are to be regarded asstandard. Values in parentheses (non-SI units), where provided,are for info
11、rmation only and are not considered standard.1.6 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 applica-bility of regula
12、tory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C757 Specification for Nuclear-Grade Plutonium DioxidePowder, SinterableC833 Specification for Sintered (Uranium-Plutonium) Diox-ide PelletsC859 Terminology Relating to Nuclear MaterialsC1145 Terminology of Advanced CeramicsC12
13、10 Guide for Establishing a Measurement System Qual-ity Control Program for Analytical Chemistry Laborato-ries Within the Nuclear IndustryD1193 Specification for Reagent WaterD7439 Test Method for Determination of Elements in Air-borne Particulate Matter by Inductively Coupled Plasma-Mass Spectromet
14、ryE1154 Specification for Piston or Plunger Operated Volu-metric Apparatus2.2 ISO Standards:3ISO 8655 Piston-Operated Volumetric Instruments (6 parts)3. Terminology3.1 DefinitionsExcept as otherwise defined herein, defini-tions of terms are as given in Terminology C859.3.2 Definitions of Terms Speci
15、fic to This Standard:3.2.1 calcination, n(calcine, v)firing or heating of agranular or particulate solid at less than fusion temperature, butsufficient to remove most of its chemically combined volatilematter and otherwise to develop the desired properties for use.C11453.2.2 reagent blank, nsolution
16、 containing all reagentsused in sample preparation, in the same quantities used forpreparation of blank and sample solutions. D74394. Summary of Dissolution Procedures4.1 Most plutonium-containing samples are dissolved withvarious mineral acids and, except for plutonium metal, withapplied heat. In s
17、ome cases, dissolution-resistant materials aredissolved in heated and sealed containers in which pressuriza-tion provides a higher temperature than is attained at ambientpressure.4.2 The dissolved materials are quantitatively transferred toa tared polyethylene dispensing bottle for subsequent delive
18、riesof weighed aliquots for high-precision analysis methods, suchas assays, or to a volumetric flask for deliveries of volumealiquots for less precise analysis methods, such as impurityanalyses. Dilute acids are used as rinses to effect quantitativetransfers and as diluents in the polyethylene dispe
19、nsing bottlesand volumetric flasks. The use of water for these purposes can,in some cases, result in hydrolysis of plutonium to producepolymers that, although soluble, are nonreactive in separationtreatments or in plutonium assay methods that have nopretreatments, such as fuming with acid.4.3 The pr
20、ocedures included in this practice are brieflydescribed in 4.4 through 4.8. Other dissolution reagents arepossible, but are not addressed in this practice. When alternatereagents are employed, the user shall verify their suitability forthe intended use.4.4 Plutonium metal is dissolved with hydrochlo
21、ric acid(Section 9 or 10) or with sulfuric acid (Section 11).4.5 Plutonium oxide, calcined at about 1000C or lower, isdissolved with a mixture of hydrochloric, nitric, and hydroflu-oric acids using the sealed-reflux techniques (Section 12) (1).4More refractory plutonium oxide is dissolved with a fus
22、ionusing sodium bisuflate flux (Section 13) (2).4.6 A mixture of nitric and hydrofluoric acid in beakers canbe used for low-fired (650C) plutonium oxide (Section 14).Open-vessel dissolution using nitric and hydrofluoric acids canbe used for low-fired plutonium oxide (Section 15) or mixedoxide (Secti
23、on 16). Closed-vessel hot block dissolution canalso be used for low-fired plutonium oxide (Section 17).Plutonium oxide fired at temperatures above 650C may alsobe dissolved using one of the methods described in Sections 14through 17 when complete dissolution can be demonstrated.4.7 Uranium-plutonium
24、 mixed oxide is dissolved in any ofthe following ways: by the sealed-reflux technique using amixture of hydrochloric, nitric, and hydrofluoric acids (Section12), by sodium bisulfate fusion (Section 13), by a heatedmixture of nitric and hydrofluoric acids in a beaker (Section14), or by open-vessel di
25、ssolution using nitric and hydrofluoricacids (Section 16).4.8 Mixed oxide pellets are dissolved using open-vesseldissolution with nitric and hydrofluoric acids (Section 18).4.9 Combinations of these dissolution techniques describedin the preceding paragraphs are sometimes used on difficult-to-dissol
26、ve samples.4.10 Quantitative transfers of samples and subsequent solu-tion are required. Whenever a loss is incurred or evensuspected, the sample is rejected. Solutions of dissolvedsamples are inspected for undissolved particles; if particles arepresent, further treatment is necessary to attain comp
27、letesolubility. When analyzing the dissolved sample for traceimpurities, caution should be exercised so the dissolution2For 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
28、to the standards Document Summary page onthe ASTM website.3Available from International Organization for Standardization (ISO), ISOCentral Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,Switzerland, http:/www.iso.org.4The boldface numbers in parentheses refer to a list of referenc
29、es at the end ofthis practice.C1168 152process does not cause the impurity to be lost or does notsignificantly increase the level of impurity being determined.5. Significance and Use5.1 Plutonium and uranium mixtures are used as nuclearreactor fuels. For use as a nuclear reactor fuel, the materialmu
30、st meet certain criteria for combined uranium and plutoniumcontent, effective fissile content, and impurity content asdescribed in Specifications C757 and C833. After dissolutionusing one of the procedures described in this practice, thematerial is assayed for plutonium and uranium to determine ifth
31、e content is correct as specified by the purchaser.5.2 Unique plutonium materials, such as alloys, compounds,and scrap metals, are typically dissolved with various acidmixtures or by fusion with various fluxes. Many plutoniumsalts are soluble in hydrochloric acid. One or more of theprocedures includ
32、ed in this practice may be effective for someof these materials; however their applicability to a particularplutonium material shall be verified by the user.6. Apparatus6.1 Ordinary laboratory apparatus are not listed, but areassumed to be present.6.2 The following items are used by most or all proc
33、edureslisted herein. Apparatus specific to one, or a few, proceduresare listed under the specific procedures where they are used.6.2.1 Balances, for weighing samples and solutions. Abalance with a sensitivity of 0.1 mg is necessary; however, abalance with 0.01 mg sensitivity is more desirable.Acalib
34、ratedbalance must be used.6.2.2 Beakers and Erlenmeyer FlasksGenerally, borosili-cate glass is recommended; however, the analyst should be surethat safety and sample contamination from the container areconsidered when choosing appropriate containers. Forexample, when hydrofluoric acid is used, the u
35、se of borosilicateglass may be avoided due to etching.6.2.3 Volumetric flasks or polyethylene dispensing bottles,for collecting the final solution from which aliquots aredispensed.6.2.4 File or brush, for cleaning plutonium metal surfaces(used in Sections 9 through 11).6.2.5 Inert Atmosphere Glove-B
36、ox Systemcapability ofmaintaining less than 10 ppm of H2O and 2 % of O2ispreferred.6.2.6 Piston-Operated Volumetric Pipettors, complyingwith the requirements of Specification E1154, applicableportions of ISO 8655 (six parts), or both.7. ReagentsNOTE 1Reagents used in specific procedures are listed w
37、ithin theprocedure or procedures where they are used. The following informationapplies to all reagents.7.1 Purity of ReagentsAll reagents used should be of thehighest purity available. Other grades may be used if they aredetermined not to affect the final result.7.2 Purity of WaterUnless otherwise i
38、ndicated, referencesto water shall be understood to mean reagent water, as definedby Type I of Specification D1193.8. Precautions8.1 Strong acids are used by these dissolution procedures.Safety glasses and gloves must be worn when handling thesesolutions. Extreme care should be exercised in using hy
39、droflu-oric acid and other hot concentrated acids. Acid solutions areevaporated by these dissolution procedures. These operationsmust be conducted in a fume hood.8.2 Hydrofluoric acid is a highly corrosive and toxic acidthat can severely burn skin, eyes, and mucous membranes.Hydrofluoric acid differ
40、s from other acids because the fluorideion readily penetrates the skin, causing destruction of deeptissue layers. Unlike other acids that are rapidly neutralized,hydrofluoric acid reactions with tissue may continue for days ifleft untreated. Familiarization and compliance with the SafetyData Sheet i
41、s essential.8.3 Extreme care is required when using procedures thatinvolve closed vessels, pressurization, or both (Sections 12 and17). Potential explosions or rupturing of vessels could injurepersonnel or breach glovebox containment, or both. Appropri-ate controls are required to prevent pressure o
42、r temperaturefrom exceeding prescribed by safety limits.9. Procedure 1 Dissolution of Plutonium Metal withHydrochloric Acid at Room Temperature9.1 Apparatus:9.1.1 Hot Plate, thermostatically controlled, capable ofmaintaining a surface temperature of up to at least 200C.NOTE 2The surface temperature
43、of a hot plate can vary considerablywith position on hot plates with large surface areas. It is thereforerecommended that the performance of the hot plate be characterizedbefore use.9.1.2 Centrifuge Tube, optional, to receive weighed sampleif beaker is not used.9.1.3 Watch glasses.9.1.4 Infrared lam
44、p.9.2 Reagents:9.2.1 Hydrochloric Acid, concentrated (sp gr 1.18), 12 M.9.2.2 Hydrochloric Acid, 6 MAdd 500 mL of 12 M HCl to500 mL of water and dilute to 1 L with water.9.2.3 Hydrochloric Acid, 1 MAdd 83 mL of 12 M HCl to900 mL of water and dilute to 1 L with water.9.2.4 Hydrofluoric Acid, concentr
45、ated (sp gr 1.17), 28 M.9.2.5 Hydrofluoric Acid, 1.3 MTransfer 4.8 mL of 28 MHF, using a plastic pipet, to a 100-mL plastic graduatedcylinder containing 90 mL of water and dilute to 100 mL withwater. Transfer to a plastic bottle for storage.9.2.6 Nitric Acid, concentrated (sp gr 1.42), 16 M.9.3 Proc
46、edure:9.3.1 Remove surface oxide, if present, from the bulksample before cutting into portions. Removal of surface oxidemay be performed by filing or brushing the plutonium metal, orby using other mechanical or chemical means.NOTE 3Plutonium metal reacts with air and moisture to form PuO2.An inert-a
47、tmosphere glovebox system can be utilized for mechanicalremoval of surface oxide, but is not recommended for removal bychemical means. Use of an inert-atmosphere glovebox system is recom-mended when preparing standards or tracers.C1168 1539.3.2 Weigh a representative sample size, considering therequ
48、ired uncertainty and the analysis method to be used.Normal sample size is 50 to 700 mg, but this may vary. Acertified sample mass, if known, may be used in lieu ofweighing.9.3.3 Transfer the weighed sample to a beaker or centrifugetube and cover with a watch glass.9.3.4 Add 6 M HCl dropwise, or in s
49、mall portions, throughthe spout of the beaker or centrifuge tube until the sampledissolves completely.9.3.5 Inspect the solution for suspended particles or depos-ited solid and, if present, warm the solution (using, forexample, an infrared lamp).9.3.6 If solid still is present, add 0.5 mL 16 M HNO3andthree drops 1.3 M HF, and heat until dissolution is complete.9.3.7 Quantitatively transfer the solution using at least fourrinses of the watch glass and beaker or centrifuge tube with 1M HCl. Transfer to a volumetric flask and bring to volumeusing 1 M HCl. Altern
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