1、Designation: C 1168 01Standard 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 7.1Dissolution of Plutonium Metal with Sulfuric Acid 7.2Dissolution of Plutonium Oxide and Uranium-Plutonium MixedOx
5、ide by the Sealed-Reflux Technique7.3Dissolution of Plutonium Oxide and Uranium-Plutonium MixedOxides by Sodium Bisulfate Fusion7.4Dissolution of Uranium-Plutonium Mixed Oxides and Low-FiredPlutonium Oxide in Beakers7.51.3 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:C 757 Specification for Nuclear-Grade Plutonium DioxidePowder, Sinterable2C 833 Specification for Sintered (Uranium-Plutonium) Di-oxide Pellets2C 1008 Specification for Sintered (Uranium-Plutonium) Di-oxide PelletsFast Reactor Fuel23. Summary of Dissolution Methods3.1 Most plutonium-contai
8、ning samples are dissolved withvarious mineral acids and, except for plutonium metal, withapplied heat. Dissolution-resistant materials are dissolved inheated and sealed containers in which pressurization providesa higher temperature than is attained at ambient pressure.3.2 Another dissolution techn
9、ique is fusion of refractoryplutonium oxide with sodium bisulfate.3.3 The dissolved materials are quantitatively transferred toa tared polyethylene dispensing bottle for subsequent deliveriesof weight aliquants for high-precision analysis methods, suchas assays, or to a volumetric flask for deliveri
10、es of volumealiquants for less precise analysis methods, such as impurityanalyses. Acids, usually 1 M, are used as rinses to effectquantitative transfers and as diluents in the polyethylenedispensing bottles and volumetric flasks. The use of water forthese purposes can, in some cases, result in hydr
11、olysis ofplutonium to produce polymers that, although soluble, arenonreactive in separation treatments or in plutonium assaymethods that have no pretreatments, such as fuming with acid.3.4 Plutonium metal is dissolved with hydrochloric acid orwith sulfuric acid.3.5 Plutonium oxide, calcined at about
12、 1000C or lower, isdissolved with a mixture of hydrochloric, nitric, and hydrof-luoric acids using the sealed-reflux techniques (1).3Morerefractory plutonium oxide is dissolved with a fusion usingsodium bisuflate (2). Low-fired (650C) plutonium oxide canalso be dissolved in a mixture of nitric and h
13、ydrofluoric acidsin beakers. Plutonium oxide fired at temperatures above 650Cmay also be dissolved in beakers using a mixture of nitric andhydrofluoric acids when complete dissolution can be demon-strated.3.6 Uranium-plutonium mixed oxide is dissolved in eitherof three ways: sodium bisulfate fusion,
14、 a heated mixture ofnitric and hydrofluoric acids in a beaker, or a mixture ofhydrochloric, nitric, and hydrofluoric acids by the sealed-refluxtechnique.3.7 Combinations of these dissolution techniques describedin 3.4 to 3.6 are sometimes used on difficult-to-dissolvesamples.3.8 Quantitative transfe
15、rs of samples and subsequent solu-tion are required. Whenever a loss is incurred or even sus-pected, the sample is rejected. Solutions of dissolved samplesare inspected for undissolved particles; if particles are present,1This practice is under the jurisdiction of ASTM Committee C26 on NuclearFuel C
16、ycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved Jan. 10, 2001. Published March 2001. Originallypublished as C 116890. Last previous edition C 116890(1995).2Annual Book of ASTM Standards, Vol 12.01.3The boldface numbers in parentheses refer to a
17、 list of references at the end ofthis practice.1Copyright ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.further treatment is necessary to attain complete solubility.When analyzing the dissolved sample for trace impurities,caution should be exercised so the dissolution
18、process does notcause the impurity to be lost or does not significantly increasethe level of impurity being determined.4. Significance and Use4.1 The materials covered are plutonium metal, plutoniumoxide, and uranium-plutonium mixed oxide, including thosethat must meet ASTM product specifications.4.
19、2 Plutonium and uranium mixtures 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. Themateria
20、l is assayed for plutonium and uranium to determine ifthe content is correct as specified by the purchaser.4.3 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 material
21、s. In general, these unique plutonium materialsare dissolved with various acid mixtures or by fusion withvarious fluxes. Many plutonium salts are soluble in hydrochlo-ric acid.5. Apparatus5.1 Balances, for weighing samples and solutions. A bal-ance with a sensitivity of 0.1 mg is necessary; however,
22、 abalance with 0.01 mg sensitivity is more desirable. A calibratedbalance must be used.5.2 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 ap
23、propriatecontainers.5.3 Furnace, with controller for timed operation. The fur-nace must be capable of maintaining an even temperature of610C up to 700C.5.4 Heating EquipmentHot plates and infrared lamps areused.5.5 Inert Atmosphere Glove-Box Systemcapability ofmaintaining less than 10 ppm of H2O and
24、 of O2is preferred.5.6 Sealed-Reflux Dissolution ApparatusThe example ap-paratus is shown in Fig. 1 and Fig. 2 and is further describedin Ref (1).6. ReagentsNOTE 1Use distilled or demineralized water for all reagents.6.1 Hydrochloric Acid (sp gr 1.18), 12 M.6.2 Hydrochloric Acid,6MAdd 500 mL of 12 M
25、 HCl to500 mL of water and dilute to 1 L with water.6.3 Hydrochloric Acid,1MAdd 83 mL of 12 M HCl to900 mL of water and dilute to 1 L with water.6.4 Hydrofluoric Acid (sp gr 1.17), 28 M.6.5 Hydrofluoric Acid, 1.3 MTransfer 4.8 mL of 28 M HF,using a plastic pipet, to a 100-mL plastic graduated cylind
26、ercontaining 90 mL of water and dilute to 100 mL with water.Transfer to a plastic bottle for storage.6.6 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 HNO3.6.7 Nitric Acid (sp gr 1.42), 16 M.6.8 Nitric Acid,1MAdd 62 mL of 16 M HNO3t
27、o 900mL of water and dilute to 1 L with water.6.9 Sodium Bisulfate, Anhydrous, Fused, NaHSO4Grindthe sodium bisulfate just before use, if necessary.6.10 Sulfuric Acid (sp gr 1.84), 18 M.6.11 Sulfuric Acid, 0.5 MCautiously add 28 mL of 18 MH2SO4to water and dilute to 1 L with water.FIG. 1 Sealed-Refl
28、ux Dissolution TubeFIG. 2 Heating BlockC 116827. Procedures7.1 Procedure 1Dissolution of Plutonium Metal with Hy-drochloric Acid:7.1.1 Remove surface oxide, if present, from the bulksample before cutting into portions. This procedure can bedone either by filing the plutonium metal in an inert atmo-s
29、phere 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 inert-atmosphere glove box.7.1.2 Weigh a representative sample size, considering therequired precision and the analysis metho
30、d to be used. Normalsample size is 50 to 700 mg, but this may vary.7.1.3 Transfer the weighed sample to a beaker or centrifugetube and cover with a watch glass.7.1.4 Cautiously add 6 M HCl dropwise through the spoutof the beaker or centrifuge tube until the sample dissolvescompletely.7.1.5 Inspect t
31、he solution for suspended particles or depos-ited solid and, if present, warm the solution.7.1.6 If solid still is present, add 0.5 mL 16 M HNO3andthree drops 1.3 M HF, and heat.7.1.7 Quantitatively transfer the solution to a previouslytared polyethylene dispensing bottle and weigh the solution ortr
32、ansfer to a volumetric flask, using at least four rinses of thewatch glass and beaker or centrifuge tube with 1 M HCl.7.1.8 Mix the solution well, equilibrate to room tempera-ture, and dispense aliquants for analysis.7.2 Procedure 2Dissolution of Plutonium Metal with Sul-furic Acid:7.2.1 If present,
33、 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 Plutonium metal reacts with air and moisture to form PuO2,so it is recommended that it be cleaned and weighed in an inert-at
34、mosphere glove box.7.2.2 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 vary.7.2.3 Transfer the weighed sample to a beaker or Erlenm-eyer flask and cover with a watch glass.7.2.4 Carefully plac
35、e 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 until the sample is dissolved.7.2.5 Inspect the solution for suspended particles or depos-ited solid and, if present, warm th
36、e solution.7.2.6 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 Erlenmeyer flask with 0.5 M sulfuricacid.7.2.7 Mix the solution well, equilibr
37、ate to room tempera-ture, and dispense aliquants for analysis.7.3 Procedure 3Dissolution of Plutonium Oxide andUranium-Plutonium Mixed Oxide by the Sealed-Reflux Tech-nique:7.3.1 Tare a weighing pan or other type of container.7.3.2 Transfer sample to the tared pan or other containeruntil the desired
38、 weight of sample is obtained, usually 0.5 g.Weigh to at least 0.1 mg sensitivity.7.3.3 Quantitatively transfer the sample from the pan into asealed-reflux tube, see Fig. 1.7.3.4 Reweigh the pan. Compute the weight of sampletransferred to the tube by subtracting the weight of the panfrom the weight
39、of the sample plus the pan.7.3.5 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 major constituent that can be used are described in Ref (1).7.3.6 Seal the tube with a stopper, clamp, and heat at 150Cin a
40、 heating block (see Fig. 2) for2horuntil the sampledissolves completely. Cool the tube to 30C before releasingthe clamp.7.3.7 Quantitatively transfer the solution to a previouslytared polyethylene dispensing bottle and weigh the solution ortransfer to a volumetric flask, using at least four rinses o
41、f thetube with 1 M HCl.7.3.8 Mix the solution well, equilibrate to room tempera-ture, and dispense aliquants for analysis.7.4 Procedure 4Dissolution of Plutonium Oxide andUranium-Plutonium Mixed Oxides by Sodium Bisulfate Fu-sion:NOTE 5This dissolution method is not recommended for use withtrace-imp
42、urity analysis methods because of the possibility of contaminat-ing the sample with impurities from the flux or beaker, or both.7.4.1 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 sil
43、icacontainer 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 choice; however, experience hasshown that borosilicate glass can be used.7.4.2 Add ten t
44、imes the sample weight of anhydrous fusedNaHSO4and carefully swirl the beaker to mix the powders.7.4.3 Cover the beaker with a watch glass and place it in acold furnace.7.4.4 Slowly heat to 600 to 625C to prevent sample spatteror temperature overshoot, or both, hold at 600 to 625C for 20to 30 min. (
45、WarningDo not exceed 600 to 625C or the 30min time limit because an insoluble component may form.)7.4.5 After cooling at room temperature for at least 30 min,add 30 to 40 mL of 0.5 M H2SO4or of water.NOTE 7Experience has shown that in this acid bisulfate medium,water can be used to dissolve the salt
46、 when maximum acid strength andsample volume cannot be exceeded. The solution should be mixedimmediately after the water is added.7.4.6 Quantitatively transfer the solution to a previouslytared polyethylene dispensing bottle and weigh the solution ortransfer to a volumetric flask, using at least fou
47、r rinses of thebeaker and watch glass with 0.5 M H2SO4.C 116837.4.7 Mix the solution well, equilibrate to room tempera-ture, and dispense aliquants for analysis.7.5 Procedure 5Dissolution of Uranium-Plutonium MixedOxides and Low-Fired (650C) Plutonium Oxide in Beakers:7.5.1 Quantitatively transfer a
48、 sample of up to 1 g that isweighed to at least 60.1 mg into a beaker.7.5.2 Add 10 to 50 mL of 0.05 M HF16 M HNO3mixture,cover with a watch glass, and heat until the sample dissolvescompletely.NOTE 8Experience has shown that a HNO3concentration in this acidmixture of 8 M or greater is adequate.7.5.3
49、 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 thebeaker and watch glass with 1 M HNO3.7.5.4 Mix the solution well, equilibrate to room tempera-ture, and dispense aliquants for analysis.8. Reliability8.1 The objectives of a dissolution treatment are completesolubility, absence of plutonium polymers, and complete re-covery in all operations. Careful laboratory practices arerequired in all operations.8.2 For optimum reliabil
