1、Designation: C 1168 08Standard Practice forPreparation and Dissolution of Plutonium Materials forAnalysis1This standard is issued under the fixed designation C 1168; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、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 practice is a compilation of dissolution techniquesfor plutonium materials that are applicable to the test methodsuse
3、d for characterizing these materials. Dissolution treatmentsfor the major plutonium materials assayed for plutonium oranalyzed for other components are listed. Aliquants of thedissolved samples are dispensed on a weight basis when one ofthe analyses must be highly reliable, such as plutonium assay;o
4、therwise they are dispensed on a volume basis.1.2 The treatments, in order of presentation, are as follows:Procedure Title SectionDissolution of Plutonium Metal with Hydrochloric Acid 9.1Dissolution of Plutonium Metal with Sulfuric Acid 9.2Dissolution of Plutonium Oxide and Uranium-Plutonium MixedOx
5、ide by the Sealed-Reflux Technique9.3Dissolution of Plutonium Oxide and Uranium-Plutonium MixedOxides by Sodium Bisulfate Fusion9.4Dissolution of Uranium-Plutonium Mixed Oxides and Low-FiredPlutonium Oxide in Beakers9.51.3 The values stated in SI units are to be regarded asstandard.1.4 This standard
6、 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 regulatory limitations prior to use.2. Referenced Documents2.1 ASTM
7、Standards:2C 757 Specification for Nuclear-Grade Plutonium DioxidePowder, SinterableC 833 Specification for Sintered (Uranium-Plutonium) Di-oxide PelletsC 859 Terminology Relating to Nuclear Materials3C 1008 Specification for Sintered (Uranium-Plutonium) Di-oxide PelletsFast Reactor Fuel3. Terminolo
8、gy3.1 Definitions: For definitions of terms used in this stan-dard, refer to C 859.4. Summary of Dissolution Methods4.1 Most plutonium-containing samples are dissolved withvarious mineral acids and, except for plutonium metal, withapplied heat. Dissolution-resistant materials are dissolved inheated
9、and sealed containers in which pressurization providesa higher temperature than is attained at ambient pressure.4.2 Another dissolution technique is fusion of refractoryplutonium oxide with sodium bisulfate flux.4.3 The dissolved materials are quantitatively transferred toa tared polyethylene dispen
10、sing bottle for subsequent deliveriesof weight aliquants for high-precision analysis methods, suchas assays, or to a volumetric flask for deliveries of volumealiquants for less precise analysis methods, such as impurityanalyses. Acids, usually 1 M, are used as rinses to effectquantitative transfers
11、and as diluents in the polyethylenedispensing bottles and volumetric flasks. The use of water forthese purposes can, in some cases, result in hydrolysis ofplutonium to produce polymers that, although soluble, arenonreactive in separation treatments or in plutonium assaymethods that have no pretreatm
12、ents, such as fuming with acid.4.4 Plutonium metal is dissolved with hydrochloric acid orwith sulfuric acid.4.5 Plutonium oxide, calcined at about 1000C or lower, isdissolved with a mixture of hydrochloric, nitric, and hydrof-luoric acids using the sealed-reflux techniques (1).4Morerefractory pluton
13、ium oxide is dissolved with a fusion usingsodium bisuflate flux (2). Low-fired (650C) plutonium oxidecan also be dissolved in a mixture of nitric and hydrofluoricacids in beakers. Plutonium oxide fired at temperatures above1This practice is under the jurisdiction of ASTM Committee C26 on NuclearFuel
14、 Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved Jan. 1, 2008. Published February 2008. Originallyapproved in 1990. Last previous edition approved in 2001 as C 1168 01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcon
15、tact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.4The boldface numbers in parentheses refer to a list of references at the end ofthis practice.1Copyright ASTM International,
16、100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Copyright by ASTM Intl (all rights reserved); Thu Feb 19 02:06:08 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.650C may also be dissolved in beakers
17、 using a mixture ofnitric and hydrofluoric acids when complete dissolution can bedemonstrated.4.6 Uranium-plutonium mixed oxide is dissolved in eitherof three ways: sodium bisulfate fusion, a heated mixture ofnitric and hydrofluoric acids in a beaker, or a mixture ofhydrochloric, nitric, and hydrofl
18、uoric acids by the sealed-refluxtechnique.4.7 Combinations of these dissolution techniques describedin 4.4 to 4.6 are sometimes used on difficult-to-dissolvesamples.4.8 Quantitative transfers of samples and subsequent solu-tion are required. Whenever a loss is incurred or even sus-pected, the sample
19、 is rejected. Solutions of dissolved samplesare inspected for undissolved particles; if particles are present,further treatment is necessary to attain complete solubility.When analyzing the dissolved sample for trace impurities,caution should be exercised so the dissolution process does notcause the
20、 impurity to be lost or does not significantly increasethe level of impurity being determined.5. Significance and Use5.1 The materials covered are plutonium metal, plutoniumoxide, and uranium-plutonium mixed oxide, including thosethat must meet ASTM product specifications.5.2 Plutonium and uranium m
21、ixtures are used as nuclearreactor fuels. For use as a nuclear reactor fuel, the materialmust meet certain criteria for combined uranium and pluto-nium content, effective fissile content, and impurity content asdescribed in Specifications C 757, C 833, and C 1008. Thematerial is assayed for plutoniu
22、m and uranium to determine ifthe content is correct as specified by the purchaser.5.3 The materials not covered are unique plutonium mate-rials, including alloys, compounds, and scrap materials. Theuser must determine the applicability of this practice to theseother materials. In general, these uniq
23、ue plutonium materialsare dissolved with various acid mixtures or by fusion withvarious fluxes. Many plutonium salts are soluble in hydrochlo-ric acid.6. Apparatus6.1 Balances, for weighing samples and solutions. A bal-ance with a sensitivity of 0.1 mg is necessary; however, abalance with 0.01 mg se
24、nsitivity is more desirable.Acalibratedbalance must be used.6.2 Beakers, Test Tubes, and Erlenmeyer FlasksGenerally, borosilicate glass is recommended; however, theanalyst should be sure that safety and sample contaminationfrom the container are considered when choosing appropriatecontainers.6.3 Fur
25、nace, with controller for timed operation. The fur-nace must be capable of maintaining an even temperature of610C up to 700C.6.4 Heating EquipmentHot plates and infrared lamps areused.6.5 Inert Atmosphere Glove-Box Systemcapability ofmaintaining less than 10 ppm of H2O and of O2is preferred.6.6 Seal
26、ed-Reflux Dissolution ApparatusThe example ap-paratus is shown in Fig. 1 and Fig. 2 and is further describedin Ref (1).6.6.1 StopperA stopper which will not react with thedissolution matrix must be used. A solid stopper inserted in ahollow, polyethylene stopper liner has been found to besatisfactory
27、. Certain fluorinated elastomers, designated asFKMs, have also found to be satisfactory.7. ReagentsNOTE 1Use distilled or demineralized water for all reagents.7.1 Hydrochloric Acid, concentrated (sp gr 1.18), 12 M.7.2 Hydrochloric Acid,6MAdd 500 mL of 12 M HCl to500 mL of water and dilute to 1 L wit
28、h water.7.3 Hydrochloric Acid,1MAdd 83 mL of 12 M HCl to900 mL of water and dilute to 1 L with water.7.4 Hydrofluoric Acid, concentrated (sp gr 1.17), 28 M.7.5 Hydrofluoric Acid, 1.3 MTransfer 4.8 mL of 28 M HF,using a plastic pipet, to a 100-mL plastic graduated cylindercontaining 90 mL of water an
29、d dilute to 100 mL with water.Transfer to a plastic bottle for storage.7.6 Hydrofluoric Acid-Nitric Acid Mixture, 0.05 M HF-16 MHNO3Add 1.8 mL 28 M HF, using a plastic pipet, to 1 L of16 M HNO3.7.7 Nitric Acid, concentrated (sp gr 1.42), 16 M.7.8 Nitric Acid,1MAdd 62 mL of 16 M HNO3to 900mL of water
30、 and dilute to 1 L with water.7.9 Sodium Bisulfate, Anhydrous, Fused, NaHSO4Grindthe sodium bisulfate to a fine powder just before use, ifnecessary.7.10 Sulfuric Acid, concentrated (sp gr 1.84), 18 M.7.11 Sulfuric Acid, 0.5 MCautiously add 28 mL of 18 MH2SO4to water and dilute to 1 L with water.FIG.
31、 1 Sealed-Reflux Dissolution TubeC1168082Copyright by ASTM Intl (all rights reserved); Thu Feb 19 02:06:08 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.8. Precautions8.1 Strong acids are used during this analysis. Safety glassesand
32、gloves must be worn when handling these solutions.Extreme care should be exercised in using hydrofluoric acidand other hot concentrated acids.Acid solutions are evaporatedduring this analysis. These operations must be conducted in afume hood.8.2 Hydrofluoric acid is a highly corrosive and toxic acid
33、that can severely burn skin, eyes, and mucous membranes.Hydrofluoric acid differs 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 d
34、ays ifleft untreated. Utilization of appropriate laboratory controlsand wearing adequate personal protective equipment to protectfrom skin and eye contact is essential.9. Procedures9.1 Procedure 1Dissolution of Plutonium Metal with Hy-drochloric Acid:9.1.1 Remove surface oxide, if present, from the
35、bulksample before cutting into portions. This procedure can bedone either by filing the plutonium metal in an inert atmo-sphere or by using other mechanical or chemical means.NOTE 2Plutonium metal reacts with air and moisture to form PuO2,so it is recommended that it be cleaned and weighed in an ine
36、rt-atmosphere glove box.9.1.2 Weigh a representative sample size, considering therequired precision and the analysis method to be used. Normalsample size is 50 to 700 mg, but this may vary.9.1.3 Transfer the weighed sample to a beaker or centrifugetube and cover with a watch glass.9.1.4 Cautiously a
37、dd 6 M HCl dropwise through the spoutof the beaker or centrifuge tube until the sample dissolvescompletely.9.1.5 Inspect the solution for suspended particles or depos-ited solid and, if present, warm the solution.9.1.6 If solid still is present, add 0.5 mL 16 M HNO3andthree drops 1.3 M HF, and heat.
38、9.1.7 Quantitatively transfer the solution to a previouslytared polyethylene dispensing bottle and weigh the solution ortransfer to a volumetric flask, using at least four rinses of thewatch glass and beaker or centrifuge tube with 1 M HCl.9.1.8 Mix the solution well, equilibrate to room tempera-tur
39、e, and dispense aliquants for analysis.9.2 Procedure 2Dissolution of Plutonium Metal with Sul-furic Acid:9.2.1 If present, remove surface oxide from the bulk samplebefore cutting into portions by filing the plutonium metal in aninert atmosphere or by using other mechanical or chemicalmeans.NOTE 3 Pl
40、utonium metal reacts with air and moisture to form PuO2,so it is recommended that it be cleaned and weighed in an inert-atmosphere glove box.9.2.2 Weigh a representative sample size, considering therequired precision and the analysis method to be used. Normalsample size is 50 to 700 mg, but this may
41、 vary.9.2.3 Transfer the weighed sample to a beaker or Erlenm-eyer flask and cover with a watch glass.9.2.4 Carefully place a TFE-fluorocarbon stirring bar in thebeaker or flask along with 30 to 40 mL of 0.5 M sulfuric acid,put the dissolution container on a magnetic stirrer, and mix thesolution unt
42、il the sample is dissolved.9.2.5 Inspect the solution for suspended particles or depos-ited solid and, if present, warm the solution.9.2.6 Quantitatively transfer the solution to a previouslytared polyethylene dispensing bottle and weigh the solution ortransfer to a volumetric flask, using at least
43、four rinses of thewatch glass and beaker or Erlenmeyer flask with 0.5 M sulfuricacid.9.2.7 Mix the solution well, equilibrate to room tempera-ture, and dispense aliquants for analysis.9.3 Procedure 3Dissolution of Plutonium Oxide andUranium-Plutonium Mixed Oxide by the Sealed-Reflux Tech-nique:9.3.1
44、 Tare a weighing pan or other type of container.9.3.2 Transfer sample to the tared pan or other containeruntil the desired weight of sample is obtained, usually 0.5 g.Weigh to at least 0.1 mg sensitivity.9.3.3 Quantitatively transfer the sample from the pan into asealed-reflux tube, see Fig. 1.9.3.4
45、 Reweigh the pan. Compute the weight of sampletransferred to the tube by subtracting the weight of the panfrom the weight of the sample plus the pan.9.3.5 Add 5 mL of 12 M HCl, 3 drops 16 M HNO3, and 3drops 1.3 M HF to the tube.NOTE 4Other acid combinations containing nitric or sulfuric acid asthe m
46、ajor constituent that can be used are described in Ref (1).FIG. 2 Heating BlockC1168083Copyright by ASTM Intl (all rights reserved); Thu Feb 19 02:06:08 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.9.3.6 Seal the tube with a stopper
47、, clamp, and heat at 150Cin a heating block (see Fig. 2)for2horuntil the sampledissolves completely. Cool the tube to 30C before releasingthe clamp.9.3.7 Quantitatively transfer the solution to a previouslytared polyethylene dispensing bottle and weigh the solution ortransfer to a volumetric flask,
48、using at least four rinses of thetube with 1 M HCl.9.3.8 Mix the solution well, equilibrate to room tempera-ture, and dispense aliquants for analysis.9.4 Procedure 4Dissolution of Plutonium Oxide andUranium-Plutonium Mixed Oxides by Sodium Bisulfate Fu-sion:NOTE 5This dissolution method is not recom
49、mended for use withtrace-impurity analysis methods because of the possibility of contaminat-ing the sample with impurities from the sodium bisulfate flux or beaker, orboth.9.4.1 Quantitatively transfer a 100 to 300-mg sample ofplutonium oxide or 1 to 1.5 g of pulverized uranium-plutoniummixed oxide to a beaker or Erlenmeyer flask. A fused silicacontainer is recommended to reduce sample contamination.The sample should be weighed to at least 60.1 mg.NOTE 6Because of the recommended temperature, fused silica or96 % silica are the container materials of c
