1、Designation: C1502 09C1502 16Standard Test Method forDetermination of Total Chlorine and Fluorine in UraniumDioxide and Gadolinium Oxide1This standard is issued under the fixed designation C1502; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, 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 chlorine and fluorine in nuclear-grade uranium d
3、ioxide (UO2) powder andpellets, nuclear grade gadolinium oxide (Gd2O3 ) powder and gadolinium oxide-uranium oxide (Gd2O3-UO2) powder and pellets.1.2 With a 2 gram UO2 sample size the detection limit of the method is 4 g/g for chlorine and 2 g/g for fluorine.The maximumconcentration determined with a
4、 2 gram sample is 500 g/g for both chlorine and fluorine. The sample size used in this test methodcan vary from 1 to 10 grams resulting in a corresponding change in the detection limits and range.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are incl
5、uded in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to
6、 use.2. Referenced Documents2.1 ASTM Standards:2C753 Specification for Nuclear-Grade, Sinterable Uranium Dioxide PowderC776 Specification for Sintered Uranium Dioxide PelletsC859 Terminology Relating to Nuclear MaterialsC888 Specification for Nuclear-Grade Gadolinium Oxide (Gd2O3) PowderC922 Specifi
7、cation for Sintered Gadolinium Oxide-Uranium Dioxide PelletsD1193 Specification for Reagent Water3. Terminology3.1 DefinitionsExcept as otherwise defined herein, definitions of terms are given in Terminology C859.3.2 Definitions of Terms Specific to This Standard:3.2.1 acceleratora chemical compound
8、 or a flux that will decrease the reaction time or prohydrolysis time.4. Summary of Test Method4.1 The halogens are separated from the test materials by pyrohydrolysis in a quartz reaction tube with a stream of wet oxygenor air at a temperature of 900 to 1000C.1000C (1-4). Chloride and fluoride are
9、volatilized simultaneously as acids, absorbed ina bufferan absorption solution as chloride and fluoride and measured with ion selective electrodes (4-6).5. Significance and Use5.1 The method is designed to show whether or not the tested materials meet the specifications as given in either Specificat
10、ionC753, C776, C888 or C922.6. Interferences6.1 The buffer absorption solution controls the pH of the measured solution to avoid hydroxide ion interference or the formationof hydrogen complexes with fluoride.1 This test method is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and
11、 is the direct responsibility of Subcommittee C26.05 on Methods of Test.Current edition approved June 1, 2009Jan. 15, 2016. Published July 2009February 2016. Originally approved in 2001. Last previous edition approved in 20012009 asC1502 01.C1502 09. DOI: 10.1520/C1502-09.10.1520/C1502-16.2 For refe
12、rencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide t
13、he user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the stand
14、ard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.2 Bromide, iodide, cyanide and sulfide, if present in the condensate, interfere in the measurement of chloride withio
15、n-selective electrodes, but have very little effect upon the measurement of fluoride with ion-selective electrodes.6.3 As the ionic activity of the chloride and fluoride ions is temperature dependent, the standard solutions and sample solutionsshould be measured at the same temperature.7. Apparatus7
16、.1 Pyrohydrolysis Equipment, the assembly of suitable equipment is shown in Fig. 1.7.2 Gas Flow Regulator and Flowmeter.7.3 Hot Plate, used to warm the water saturating the sparge gas to 5080C.50 to 80C.7.4 Combustion Tube Furnace, having a bore of about 32 mm with a length of about 300 mm and the c
17、apability of maintaininga temperature of 950 6 25C. Combustion tube furnaces with different dimensions may be satisfactory. Temperatures between 900and 1000C have been found to be satisfactory.7.5 Quartz Reaction Tube (Fig. 2)The exit end should not extend more than 50 mm beyond the furnace with a g
18、round jointconnecting to the delivery tube. The delivery tube extends into a polyethylene or Pyrex absorption vessel with a tip capable ofgiving a stream of very fine bubbles. A second absorption vessel connected in series, may be necessary to ensure completecollection of the fluorine and chlorine f
19、rom the sample.7.6 Combustion Boat, a ceramic, platinum or quartz boat with a 10 mL capacity (approx. 90100 90 to 100 mm long, 13 mmwide, and 10 mm high). Boats with different dimensions may be satisfactory.7.7 Absorption Vessel, a 50-ml polyethylene graduate or tube is satisfactory.7.8 Ion-Selectiv
20、e Electrodes, fluoride-selective activity electrode, chloride-selective activity electrodeelectrode Combinationelectrodes may be suitable.7.9 Double-Junction Reference Electrode, ,such as a silver-silver chloride with appropriate filling solutions.7.10 pH/mV MeterThe meter should have minimum resolu
21、tion of 1 mV.7.11 Magnetic Stirrer.7.12 Beakers, 50 mL polyethylene.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents conform to the specifications of the Committee on Analytical Reagents of the American C
22、hemical Society, where suchspecifications are available.3 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purityto permit its use without lessening the accuracy of the determination.3 Reagent Chemicals, American Chemical Society Specifications, Ame
23、rican Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (
24、USPC), Rockville, MD.FIG. 1 Pyrohydrolysis EquipmentC1502 1628.2 AcceleratorTwo accelerators have been investigated for this system, halogen free U3O8 and a flux of sodium tungstate andtungsten trioxide.trioxide (1, 2). Halogen free U3O8 requires no special preparation before use but will require a
25、longerpyrohydrolysis period.The flux of sodium tungstate (Na2WO4) with tungsten trioxide (WO3) may reduce the pyrohydrolysis periodby half but it requires the following special preparation. Dehydrate 165 g of Na2WO4 in a large platinum dish. Transfer the driedmaterial to a mortar, add 116 g of WO3,
26、and grind the mixture to ensure good mixing. Transfer the mixture into a platinum dishand heat with a burner for 2 h. Cool the melt, transfer the flux to a mortar and grind to a coarse powder. Store the flux in an airtightbottle. Mix about 8 g of flux with each portion of sample to be pyrohydrolyzed
27、.8.3 BufferAbsorption Solution (0.1 M)Dissolve 10 g, potassium acetate (KC2H3O2) in water, add 5 mL of acetic acid(CH3CO2H, sp gr 1.05), and dilute to 1 L. Other buffers absorption solutions may be satisfactory. It will be necessary to validatethe buffers absorption solutions and operating condition
28、s with spike recovery determinations.8.4 Chloride, Standard Solution (100 g Cl/mL)Dissolve 0.165 g of dry sodium chloride (NaCl) in water and dilute to 1 L.Commercially prepared standard solutions may be used.8.5 Fluoride, Standard Solution (50 g F/mL)Dissolve 0.111 g of dried sodium fluoride (NaF)
29、in water and dilute to 1 L. Storethe solution in a polyethylene bottle. Commercially prepared standard solutions may be used.8.6 Compressed Oxygen or Air.8.7 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean reagent water conforming toSpecification D1193, Typ
30、e I.9. Procedure9.1 Adjust the pyrohydrolysis system to operating condition as follows:9.1.1 Heat the furnace to 950 6 25C. (See 6.47.4).9.1.2 Fill the water reservoir and heat to 50 to 80C.9.1.3 Adjust the gas flow to 1 to 2 L/min.9.1.3.1 The furnace temperature, the gas flow, and the dimensions of
31、 the delivery tube tip are critical variables that will affectthe spike recovery of the method.9.2 Flush the quartz reaction tube and boat with moist oxygen.9.3 Run a pyrohydrolysis blank using a halogen-free uranium oxide or gadolinium oxide according to the procedure in 8.59.5.9.3.1 Alternatively
32、an empty combustion boat can be used for the pyrohydrolysis blank.9.3.2 A blank run should be made each day and after any sample that contains abnormally high levels of chlorine or fluorine.9.4 Run samples, controls, duplicates and spikes in accordance with the users quality assurance control plan a
33、nd requirements.9.5 Sample Pyrohydrolysis:9.5.1 Pellets should be crushed prior to analysis.9.5.2 Weigh 1 to 10 g of sample and spread in the combustion boat. If an accelerator is desired, mix 4 g of U3O8 acceleratoror 8 g of the tungstate flux with the sample before spreading in the boat. A flux to
34、 sample ratio of 1 has been found to worksatisfactorily. Other ratios may be applicable as determined by the analyst.NOTE 1All dimensions in millimetres.FIG. 2 Quartz Reaction TubeC1502 1639.5.3 Place 15 mL of acetate buffer absorption solution in the collection flask polyethylene absorption vessel
35、and submerge thedelivery tip in the solution.9.5.4 Remove the stopper from the entrance of the quartz reaction tube and insert the boat into the hot area of the furnace.Quickly stopper the furnace quartz reaction tube.9.5.5 Check the gas flow and adjust to 1 to 2 L/min.9.5.6 Continue the reaction fo
36、r 1 hour. Thirty minutes may be sufficient with the tungstate flux.NOTE 1The time required to complete the pyrohydrolysis will vary with differences in accelerator type, equipment and sample type. To establish thetotal time required for complete pyrohydrolysis, replace the bufferabsorption solution
37、at 15 to 30 minute intervals and continue the reaction until complete.9.5.7 When the pyrohydrolysis is completed, transfer the bufferabsorption solution to a 25-mL volumetric flask. Rinse thedelivery tube (including inside) and collection tube the polyethylene absorption vessel with a minimum of buf
38、ferabsorptionsolution. Make up to volume with buffer.the absorption solution.9.6 Chloride and Fluoride Measurement:9.6.1 Assemble the mV meter and ion specificselective electrode and take the meter readings in accordance with themanufacturers instructions.9.6.2 Add 0, 0.1, 0.2, 0.4, 0.8, 1, 2, 4 and
39、 10 mL of the chloride standard solution and the fluoride solutions standard solutionprepared in 7.48.4 and 7.58.5 to separate 25 mL flasks. Dilute each with bufferabsorption solution. Prepare calibration curves byplotting the millivolt readings of the standards versus the concentration in microgram
40、s per 25 mL on semi-log paper. Theconcentration of chloride covers 10 g/25 mL to 1000 g/25 mL and the fluoride from 5 g/25 mL to 500 g/25 mL.9.6.3 Use one half of the diluted sample from 8.5.79.5.7 for each of the halide determinations. Read the concentrations fromthe calibration curves. Alternative
41、ly the spike addition technique may be applicable as determined by the analyst.NOTE 2The chloride and fluoride measurements may be determined using ion chromatography. Appropriate bufferabsorption solutions that arecompatible with ion chromatography, will be necessary. The solutions will require spi
42、ke recovery test work.10. Calculations10.1 ChlorineCalculate as follows:Cl, g/g 5C 2B!W (1)where:C = micrograms of total chlorine in absorber solution,C = micrograms of total chlorine in absorption solution,B = micrograms of total chlorine in the pyrohydrolysis blank, andW = sample weight in grams.1
43、0.2 If a second sample solution was generated in a secondary impingerabsorption vessel as described in 6.57.5 calculate theresult of the second impinger absorption vessel in the same manner as 9.110.1. The total micrograms of chlorine in the sample isthe sum of both impingers.10.3 FluorineCalculate
44、as follows:F, g/g 5F 2B!W (2)where:F = micrograms of total fluorine in absorber solution,B = micrograms of total fluorine in the pyrohydrolysis blank, andW = sample weight in grams.10.4 If a second sample solution was generated in a secondary impingerabsorption vessel as described in 6.57.5 calculat
45、e theresult of the second impinger absorption vessel in the same manner as 9.310.3. The total micrograms of fluorine in the sample isthe sum of both impingers.absorption vessels.11. Precision and Bias11.1 Uranium Dioxide:11.1.1 PrecisionThe standard deviation for the method is given in Table 1. The
46、data were obtained over several months bydifferent analysts in laboratory A.11.1.2 BiasThere is no accepted reference material available.The bias of the method was evaluated by spiking 4 gram samplesof uranium oxide powder. The powder was prepared by furnace oxidation of UO2 at 950C. The spiking sol
47、ution was addeddirectly to the sample in the combustion boat. The sample was dried at 110C for 30 min. before pyrohydrolysis. The data in Table3 were obtained during a five week period using one furnace by one analyst in Laboratory A.11.1.3 The supporting data for Table 1 are available from ASTM hea
48、dquarters.C1502 16411.2 Gadolinium Oxide:11.2.1 PrecisionThe standard deviation for the method is shown in Table 2. The data were obtained during a one month periodusing three different furnaces.11.2.2 BiasThere is no accepted reference material available. The bias of the method was evaluated by spi
49、king a sample ofGd2O3-UO2 pellets. The data in Table 2 were obtained during a one month period using three different furnaces at laboratory B.11.2.3 The supporting data for Table 2 are available from ASTM headquarters.12. Keywords12.1 chlorine; fluorine; gadolinium oxide; uranium dioxideREFERENCES(1) American Standards Association, Inc., “Referee Methods for the Chemical Analysis of Nuclear Fuels,” ASA N5.7, 1965, p. 37.(2) Powell, R.H., and Menis, O., “Separation of Fluoride from Inorganic Compounds by Pyrolysis,” Analytical
