1、Designation: C 1502 09Standard Test Method forDetermination of Total Chlorine and Fluorine in UraniumDioxide and Gadolinium Oxide1This standard is issued under the fixed designation C 1502; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, 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 test method covers the determination of chlorineand fluorine in nuclear-grade uranium dioxide
3、(UO2) powderand pellets, nuclear grade gadolinium oxide (Gd2O3) powderand gadolinium oxide-uranium oxide (Gd2O3-UO2) powderand pellets.1.2 With a 2 gram UO2sample size the detection limit of themethod is 4 g/g for chlorine and 2 g/g for fluorine. Themaximum concentration determined with a 2 gram sam
4、ple is500 g/g for both chlorine and fluorine. The sample size usedin this test method can vary from 1 to 10 grams resulting in acorresponding change in the detection limits and range.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisst
5、andard.1.4 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 regulatory limitations prior to use.2. Refer
6、enced Documents2.1 ASTM Standards:2C 753 Specification for Nuclear-Grade, Sinterable UraniumDioxide PowderC 776 Specification for Sintered Uranium Dioxide PelletsC 888 Specification for Nuclear-Grade Gadolinium Oxide(Gd2O3) PowderC 922 Specification for Sintered Gadolinium Oxide-Uranium Dioxide Pell
7、etsD 1193 Specification for Reagent Water3. Summary of Test Method3.1 The halogens are separated from the test materials bypyrohydrolysis in a quartz tube with a stream of wet oxygen orair at a temperature of 900 to 1000C. (1-4) Chloride andfluoride are volatilized simultaneously as acids, absorbed
8、in abuffer solution as chloride and fluoride and measured with ionselective electrodes (4-6).4. Significance and Use4.1 The method is designed to show whether or not thetested materials meet the specifications as given in eitherSpecification C 753, C 776, C 888 or C 922.5. Interferences5.1 The buffe
9、r controls the pH of the measured solution toavoid hydroxide ion interference or the formation of hydrogencomplexes with fluoride.5.2 Bromide, iodide, cyanide and sulfide, if present in thecondensate, interfere in the measurement of chloride withion-selective electrodes, but have very little effect
10、upon themeasurement of fluoride with ion-selective electrodes.5.3 As the ionic activity of the chloride and fluoride ions istemperature dependent, the standard solutions and samplesolutions should be measured at the same temperature.6. Apparatus6.1 Pyrohydrolysis Equipment, the assembly of suitablee
11、quipment is shown in Fig. 1.6.2 Gas Flow Regulator and Flowmeter.6.3 Hot Plate, used to warm the water saturating the spargegas to 5080C.6.4 Combustion Tube Furnace, having a bore of about 32mm with a length of about 300 mm and the capability ofmaintaining a temperature of 950 6 25C. Combustion tube
12、furnaces with different dimensions may be satisfactory. Tem-peratures between 900 and 1000C have been found to besatisfactory.6.5 Quartz Reaction Tube (Fig. 2)The exit end should notextend more than 50 mm beyond the furnace with a groundjoint connecting to the delivery tube. The delivery tube extend
13、sinto a polyethylene or Pyrex absorption vessel with a tipcapable of giving a stream of very fine bubbles. A secondabsorption vessel connected in series, may be necessary toensure complete collection of the fluorine and chlorine fromthe sample.1This test method is under the jurisdiction of ASTM Comm
14、ittee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved June 1, 2009. Published July 2009. Originally approvedin 2001. Last previous edition approved in 2001 as C1502 01.2For referenced ASTM standards, visit the ASTM website,
15、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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.FI
16、G. 1 Pyrohydrolysis EquipmentFIG. 2 Quartz Reaction TubeC15020926.6 Combustion Boat, a ceramic, platinum or quartz boatwith a 10 mL capacity (approx. 90100 mm long, 13 mm wide,and 10 mm high). Boats with different dimensions may besatisfactory.6.7 Absorption Vessel, a 50-ml polyethylene graduate ort
17、ube is satisfactory.6.8 Ion-Selective Electrodes, fluoride-selective activity elec-trode3, chloride-selective activity electrode4. Combinationelectrodes may be suitable.6.9 Double-Junction Reference Electrode5, such as a silver-silver chloride with appropriate filling solutions.6.10 pH/mV MeterThe m
18、eter should have minimum reso-lution of 1 mV.6.11 Magnetic Stirrer.6.12 Beakers, 50 mL polyethylene.7. Reagents7.1 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 onAnalyti
19、cal Reagents of the American Chemical Society, wheresuch specifications are available.6Other 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 AcceleratorTwo accelerators have be
20、en investigatedfor this system, halogen free U3O8and a flux of sodiumtungstate and tungsten trioxide. (1, 2) Halogen free U3O8requires no special preparation before use but will require alonger pyrohydrolysis period. The flux of sodium tungstate(Na2WO4) with tungsten trioxide (WO3) may reduce thepyr
21、ohydrolysis period by half but it requires the followingspecial preparation. Dehydrate 165 g of Na2WO4in a largeplatinum dish. Transfer the dried material to a mortar, add 116gofWO3, and grind the mixture to ensure good mixing.Transfer the mixture into a platinum dish and heat with aburner for 2 h.
22、Cool the melt, transfer the flux to a mortar andgrind to a coarse powder. Store the flux in an airtight bottle.Mix about8goffluxwith each portion of sample to bepyrohydrolyzed.7.3 Buffer Solution (0.1 M)Dissolve 10 g, potassiumacetate (KC2H3O2) in water, add 5 mL of acetic acid(CH3CO2H, sp gr 1.05),
23、 and dilute to 1 L. Other buffers may besatisfactory. It will be necessary to validate the buffers andoperating conditions with spike recovery determinations.7.4 Chloride, Standard Solution (100 g Cl/mL)Dissolve0.165 g of dry sodium chloride (NaCl) in water and dilute to 1L. Commercially prepared st
24、andard solutions may be used.7.5 Fluoride, Standard Solution (50 g F/mL)Dissolve0.111 g of dried sodium fluoride (NaF) in water and dilute to 1L. Store the solution in a polyethylene bottle. Commerciallyprepared standard solutions may be used.7.6 Compressed Oxygen or Air.7.7 Purity of WaterUnless ot
25、herwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D 1193, Type I.8. Procedure8.1 Adjust the pyrohydrolysis system to operating conditionas follows:8.1.1 Heat the furnace to 950 6 25C. (See 6.4).8.1.2 Fill the water reservoir and heat to 50 to
26、80C.8.1.3 Adjust the gas flow to 1 to 2 L/min.8.1.3.1 The furnace temperature, the gas flow and thedimensions of the delivery tube tip are critical variables thatwill affect the spike recovery of the method.8.2 Flush the reaction tube and boat with moist oxygen.8.3 Run a pyrohydrolysis blank using a
27、 halogen-free ura-nium oxide or gadolinium oxide according to the procedure in8.5.8.3.1 Alternatively an empty combustion boat can be usedfor the pyrohydrolysis blank.8.3.2 A blank run should be made each day and after anysample that contains abnormally high levels of chlorine orfluorine.8.4 Run sam
28、ples, controls, duplicates and spikes in accor-dance with the users quality assurance control plan andrequirements.8.5 Sample Pyrohydrolysis:8.5.1 Pellets should be crushed prior to analysis.8.5.2 Weigh 1 to 10 g of sample and spread in the combus-tion boat. If an accelerator is desired, mix4gofU3O8
29、accelerator or8gofthetungstate flux with the sample beforespreading in the boat. A flux to sample ratio of 1 has beenfound to work satisfactorily. Other ratios may be applicable asdetermined by the analyst.8.5.3 Place 15 mL of acetate buffer solution in the collectionflask and submerge the delivery
30、tip in the solution.8.5.4 Remove the stopper from the entrance of the reactiontube and insert the boat into the hot area of the furnace.Quickly stopper the furnace tube.8.5.5 Check the gas flow and adjust to 1 to 2 L/min.8.5.6 Continue the reaction for 1 hour. Thirty minutes maybe sufficient with th
31、e tungstate flux.NOTE 1The time required to complete the pyrohydrolysis will varywith differences in accelerator type, equipment and sample type. Toestablish the total time required for complete pyrohydrolysis, replace thebuffer solution at 15 to 30 minute intervals and continue the reaction untilco
32、mplete.8.5.7 When the pyrohydrolysis is completed, transfer thebuffer solution to a 25-mL volumetric flask. Rinse the deliverytube (including inside) and collection tube with a minimum ofbuffer solution. Make up to volume with buffer.8.6 Chloride and Fluoride Measurement:8.6.1 Assemble the mV meter
33、and ion specific electrode andtake the meter readings in accordance with the manufacturersinstructions.3The Orion Model 9409 has been found satisfactory.4The Orion Model 9617 has been found satisfactory.5The Orion Model 9002 has been found satisfactory.6Reagent Chemicals, American Chemical Society S
34、pecifications , AmericanChemical Society, Washington, D.C. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Reagent Chemicals and Standards,byJoseph Rosin, D. Van Nostrand Company, Inc., New York, New York, and theUnited States Pharmacopeia.C15020938.6.2 Add
35、 0, 0.1, 0.2, 0.4, 0.8, 1, 2, 4 and 10 mL of thechloride and the fluoride solutions prepared in 7.4 and 7.5 toseparate 25 mLflasks. Dilute each with buffer solution. Preparecalibration curves by plotting the millivolt readings of thestandards versus the concentration in micrograms per 25 mLonsemi-lo
36、g paper. The concentration of chloride covers 10 g/25mL to 1000 g/25 mL and the fluoride from 5 g/25 mL to 500g/25 mL.8.6.3 Use one half of the diluted sample from 8.5.7 for eachof the halide determinations. Read the concentrations from thecalibration curves. Alternatively the spike addition techniq
37、uemay be applicable as determined by the analyst.NOTE 2The chloride and fluoride measurements may be determinedusing ion chromatography. Appropriate buffer solutions that are compat-ible with ion chromatography, will be necessary. The solutions will requirespike recovery test work.9. Calculations9.1
38、 ChlorineCalculate as follows:Cl, g/g 5C B!W(1)where:C = micrograms of total chlorine in absorber solution,B = micrograms of total chlorine in the pyrohydrolysisblank, andW = sample weight in grams.9.2 If a second sample solution was generated in a second-ary impinger vessel as described in 6.5 calc
39、ulate the result ofthe second impinger in the same manner as 9.1. The totalmicrograms of chlorine in the sample is the sum of bothimpingers.9.3 FluorineCalculate as follows:F, g/g 5F B!W(2)where:F = micrograms of total fluorine in absorber solution,B = micrograms of total fluorine in the pyrohydroly
40、sisblank, andW = sample weight in grams.9.4 If a second sample solution was generated in a second-ary impinger vessel as described in 6.5 calculate the result ofthe second impinger in the same manner as 9.3. The totalmicrograms of fluorine in the sample is the sum of bothimpingers.10. Precision and
41、Bias10.1 Uranium Dioxide:10.1.1 PrecisionThe standard deviation for the method isgiven in Table 1. The data were obtained over several monthsby different analysts in laboratory A.10.1.2 BiasThere is no accepted reference material avail-able. The bias of the method was evaluated by spiking 4 gramsamp
42、les of uranium oxide powder. The powder was preparedby furnace oxidation of UO2at 950C. The spiking solutionwas added directly to the sample in the combustion boat. Thesample was dried at 110C for 30 min. before pyrohydrolysis.The data in Table 3 were obtained during a five week periodusing one furn
43、ace by one analyst in Laboratory A.10.1.3 The supporting data for Table 1 are available fromASTM headquarters.10.2 Gadolinium Oxide:10.2.1 PrecisionThe standard deviation for the method isshown in Table 2. The data were obtained during a one monthperiod using three different furnaces.10.2.2 BiasTher
44、e is no accepted reference material avail-able. The bias of the method was evaluated by spiking a sampleof Gd2O3-UO2pellets. The data in Table 2 were obtainedduring a one month period using three different furnaces atlaboratory B.10.2.3 The supporting data for Table 2 are available fromASTM headquar
45、ters.11. Keywords11.1 chlorine; fluorine; gadolinium oxide; uranium dioxideTABLE 1 Standard DeviationUranium DioxideSampleTypeElementConcentration(g/g)StandardDeviation(g/g)DeterminationsUO2powderA Fluorine 28 2 20UO2powderA Chlorine 38 4 20UO2powderB Fluorine 18 2 20TABLE 2 Standard DeviationGadoli
46、nium OxideSampleTypeElementSpike(g)Mean(g)StandardDeviationBiasEstimateNumber ofDeterminationsGd2O3-UO2pelletsFluorine 50 49 4 1 31Gd2O3-UO2pelletsChlorine 50 50 5 0 31C1502094REFERENCES(1) American Standards Association, Inc., “Referee Methods for theChemical Analysis of Nuclear Fuels,” ASA N5.7, 1
47、965, p. 37.(2) Powell, R.H., and Menis, O., “Separation of Fluoride from InorganicCompounds by Pyrolysis,” Analytical Chemistry, ANCHA, Vol 30,1958, p. 1546.(3) Warf, J.C., Cline, W.E., and Tevebaugh, R.D., “Pyrohydrolysis in theDetermination of Fluoride and Other Halides,” Analytical Chemistry,ANCH
48、A, Vol 26, 1954, p. 342.(4) Plucinski, C.E., “Determination of Microgram Quantities of Fluoridein Metal Oxides,” USAEC Document BNWL-601, AEROB, 1968.(5) Frant, M.S., and Ross, J.W., Jr., “Electrode for Sensing Fluoride IonActivity in Solution,” Science, KAGTA, Vol 154, 1966, p. 1553.(6) Rechnitz, G
49、.A., “Ion-Selective Electrodes,” Chemical and EngineeringNews, CENEA, Vol 25, 1967, p. 1946.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed
