1、Designation: C1430 07 (Reapproved 2011)1C1430 18Standard Test Method forDetermination of Uranium, Oxygen to Uranium (O/U), andOxygen to Metal (O/M) in Sintered Uranium Dioxide andGadolinia-Uranium Dioxide Pellets by AtmosphericEquilibration1This standard is issued under the fixed designation C1430;
2、the number immediately following the designation indicates the year oforiginal adoption or, in the case 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
3、 NOTEA units statement was added editorially in June 2011.1. Scope1.1 This test method applies to the determination of uranium, the oxygen to uranium (O/U) ratio in sintered uranium dioxidepellets, and the oxygen to metal (O/M) ratio in sintered gadolinium oxide-uranium dioxide pellets with a Gd2O3
4、concentration ofup to 12 weight %. The O/M calculations assume that the gadolinium and uranium oxides are present in a metal dioxide solidsolution.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not
5、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 safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use. For specific h
6、azards statements, see Section 89.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Org
7、anization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C696 Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Uranium DioxidePowders and PelletsC776 Specification for Sintered Uranium Dioxide Pellets for Light Water
8、 ReactorsC859 Terminology Relating to Nuclear MaterialsC922 Specification for Sintered Gadolinium Oxide-Uranium Dioxide PelletsC968 Test Methods for Analysis of Sintered Gadolinium Oxide-Uranium Dioxide PelletsC1287 Test Method for Determination of Impurities in Nuclear Grade Uranium Compounds by In
9、ductively Coupled PlasmaMass Spectrometry3. Terminology3.1 Definitions:3.1.1 For definitions of terms relating to the nuclear fuel cycle, refer to Terminology C859.4. Summary of Test Method4.1 The uranium, and either O/U or O/M, are determined by measuring the weight change of a sintered pellet afte
10、r it has beenexposed to an equilibrating atmosphere to bring it to the stoichiometric condition. Sintered pellets are weighed and loaded into asample boat. The boat is placed in a tube furnace capable of holding a temperature of 800 6 10C. The furnace is purged witha moist gas flow of 4 % hydrogen a
11、nd 96 % argon or nitrogen to remove all air. The temperature of the furnace is raised to 800C1 This test method is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.Current edition approved June 1, 2011Feb. 1
12、, 2018. Published June 2011February 2018. Originally approved in 2000. Last previous edition approved in 20072011 asC1430C1430 07 (2011)107 DOI: 10.1520/C1430-07R11E01.10.1520/C1430-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm
13、.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 the user of an ASTM standard an indication of what changes have been made to the previous version. Because
14、it 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 standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr
15、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1and held at this temperature with constant gas flow for 4 h. The furnace then is turned off and allowed to cool, with gas purge on,to room temperature. The samples are removed from the furnace and reweighed.4.2 The weight ch
16、ange, gadolinia content, and chemical impurity content are used to calculate % uranium and the O/U or O/M.5. Significance and Use5.1 Uranium dioxide is used as a nuclear-reactor fuel. This test method is designed to determine whether the percent uraniumand O/U or O/M content meet Specifications C776
17、 and C922.6. Interferences6.1 Parameters for temperature, gas composition, gas flow, and moist air purge must be monitored and maintained carefullywithin the limits set in the procedure.6.2 This test method assumes that chemical impurities meet Specifications C776 and C922 limits. Potential methodin
18、terferences from higher impurity concentrations will require evaluation.6.3 Furnace tubes or boats made from metals that oxidize under the test conditions may prevent proper equilibration byconsuming available oxygen.6.4 Precise weighing of samples is critical to the accuracy of this test method.6.5
19、 Loss of weight due to pellet chipping would invalidate the analysis. Handle pellets with care.6.6 This test method assumes that pellets are sintered. It does not correct for moisture or volatile additives.6.7 This test method assumes that UO2-Gd2O3 pellets have formed a solid solution; however, the
20、 error from incompletedissolution of Gd2O3 would be very small (see the calculation in 10.211.2).7. Apparatus7.1 Analytical Balance, capable of weighing to 6 0.0001 g.7.2 Tube Furnace, capable of controlling temperatures at 800 6 10C, that has been fitted with a fused quartz furnace tube.7.3 Fused Q
21、uartz Sample Boats.7.4 Assorted Connectors, Tubing, Flasks, Stoppers, and Delivery TubesThe purge gas is passed through a humidifier, into thetube furnace. A bubbler flask is attached to the furnace outlet to monitor gas flow (see Fig. 1).7.5 Gas Pressure Gage and Regulator.FIG. 1 Assorted Connector
22、s, Tubing, Flasks, Stoppers, and Delivery TubesC1430 1827.6 Purge Gas (4 % hydrogen, 96 % argon or 4 % hydrogen and 96 % nitrogen. Gas purity of 99.995 % has been found toperform satisfactorily.7.7 Purge Gas Humidifier, with heater and controller capable of maintaining water temperature at 35 6 10C.
23、8. Standard Materials8.1 NBL3,NBL-traceable, or equivalent, uranium dioxide pellets. Analyze at least one standard pellet per batch.9. Hazards and Precautions9.1 Take proper safety precautions for handling uranium.9.2 The furnace, sample tube and sample boats are heated to 800C. Care must be taken t
24、o avoid burns.9.3 Exercise appropriate caution when working with compressed gasses.10. Procedure10.1 Analyze samples as whole pellets. No preparation is required. The nominal sample size is 510-g pellet. Smaller pelletsmay need to be composited (two pellets/test) to maintain minimum weight. Avoid us
25、ing chipped or cracked pellets.10.2 Place a small weighing tray or watch glass on the balance pan. Tare the balance and check to ensure that the balance isstable. If the balance will not stabilize, do not proceed.NOTE 1The extremely small weight changes that are being measured in this test method ma
26、ke it critical that the balance is working properly.10.3 Weigh a check weight at least daily to confirm that the analytical balance is operating correctly.10.4 Create a boat map to maintain sample identity.10.5 Use a pair of tweezers and carefully weigh the pellet. Rezero the balance and repeat the
27、pellet weighing until a consistentweight is obtained. Carefully place the pellet in the quartz sample boat. Repeat for each pellet.10.6 Include one or two equilibrated standard control pellets with each sample batch.10.7 Carefully place the loaded boat into the sample tube. Position the boat as clos
28、e to center of the furnace tube as possible.10.8 Fit the purge gas connection to end of tube and clamp. Make certain that the water in the humidifying flask is at 35 6 10C(6 5C is optimal) and check the gas cylinder pressure to verify there is sufficient gas to complete the cycle.10.9 Turn on the ga
29、s flow and allow the chamber to purge for approximately five minutes.NOTE 2The flow rate of the purge gas and the length of the purge cycle will vary with the size of the furnace tube. A purge of greater than or equalto three furnace volumes/minute is the recommended minimum.The flow rate must be ad
30、equate to maintain a positive pressure inside the sample chamber.10.10 Attach a Pyrex delivery tube with ground glass fitting to the exit end of the furnace, and place the end in a containerof water to verify and monitor the gas flow.10.11 Turn on the furnace and bring the temperature to 800C.10.12
31、After temperature is reached, allow the pellets to equilibrate for a minimum of 4 h. Monitor the system occasionallyduring the run to ensure constant temperature and gas flow.10.13 At the end of the 4-h cycle, turn the furnace down to 50C and allow the samples to cool. The purge gas flow must bemain
32、tained until the samples reach 50C. Then, turn off the carrier gas and allow the pellets to cool to room temperature.NOTE 3If the samples are allowed to cool to room temperature while the purge gas is flowing, the water in the purge gas will begin to condense insidethe tube and on the pellets. A tem
33、perature of 50C is high enough to prevent condensation but low enough to prevent oxidation by room air.10.14 Remove the sample boat and reweigh the pellets immediately. Use multiple weighings as necessary to obtain a consistentweight.11. Calculation11.1 O/U (UO2 Pellets):52.0002 W2 2W1!W2!AWo!/AWu 1
34、2AWo!#(1)52.0002 W2 2W1!W2!0.0593!3 Available from the New Brunswick Laboratory, 9800 S. Cass Ave., Argonne, IL.C1430 183where:W1 = Weight of sample before equilibration, g,W2 = Weight of sample after equilibration, g,AWo = Atomic weight of oxygen,AWu = Atomic weight of uranium, and0.0593 = AWo!AWu
35、12AWo! .11.2 O/M (UO2-Gd2O3 Pellets):Pellet O/M52.0002O/M (2)52.0002 W2 2W1!W2!0.05931%Gd2O3 30.00026!#where:W1 = Weight of sample before equilibration, g,W2 = Weight of sample after equilibration, g,% Gd2O3 = Measured Gd, expressed as stoichiometric weight % Gd2O3, and(% Gd2O3)(0.00026) = Correctio
36、n factor for weight gain due to formation of oxygen-rich UO2-Gd2O3 solid solution duringsintering. For processes that do not produce a 100 % solid solution, this factor should be evaluated todetermine if modification is necessary (see Appendix X1).11.3 Percent Uranium:11.3.1 Percent Uranium, Based o
37、n Sample Weight:%U 5F1002G 2%I!15.9994 G2FO/M 3G157.25 GFO/MAWuG1F 115.9994G (3)TABLE 1 Stoichiometric Factors to Convert Metals to OxidesOxide Conversion Factors for Impurity CalculationAElement Oxide FactorAl Al2O3 1.89B B2 O3 3.23Ba Ba O 1.12Be Be O 2.78Ca Ca O 1.40Cd Cd O 1.14Co Co2O3 1.41Cr Cr2
38、O3 1.46Cu Cu O 1.25Dy Dy2 O3 1.15Eu Eu2O3 1.16Fe Fe2 O3 1.43Gd Gd2 O3 1.15Hf Hf O2 1.18Li Li2 O 2.15Mg Mg O 1.66Mn MnO2 1.58Mo Mo O3 1.50Na Na2 O 1.35Ni Ni O 1.27P P2 O5 2.29Pb Pb O2 1.15Sb Sb2 O4 1.26Si Si O2 2.14Sm Sm2 O3 1.16Sn Sn O2 1.27Ta Ta2 O5 1.22Th Th O2 1.14Ti Ti O2 1.67V V2 O5 1.79W W O3
39、1.26Zn Zn O 1.24Zr Zr O2 1.35AOxide conversion factor is defined as grams oxide per gram of element.C1430 184where:G = Weight % Gd = weight % Gd2O3 0.86759%I = Total nonvolatile impurities, expressed as weight % impurity oxides in UO2.Add the weight % of each detected impurityoxide plus a correction
40、 factor to account for less than threshold of detection impurities. This correction factor will needto be determined for each facility.Afactor of 0.01 % has been found to provide satisfactory results. See Table 1 to obtainconversion factors to convert common impurity elements to oxides.The list of i
41、mpurities to be tested for will depend upon specification requirements (see Specifications C776 and C922),elements obtained from multielement methods (see Test Methods C696, C968, and C1287), and fuel processingconditions. In some cases, a nominal value for impurities is adequate.O/M = Oxygen/uraniu
42、m ratio or oxygen/metal ratio calculated in 10.1 or 10.2, respectively.O/M = Oxygen/uranium ratio or oxygen/metal ratio calculated in 11.1 or 11.2, respectively.AWu = Atomic weight of uranium. Normally for U-235 enrichment of approximately 4 %, a nominal value of 237.96 may beused. For accuracy bett
43、er than 0.03 %, or for U-235 enrichments 5 %, calculate the actual atomic weight.11.3.2 Percent Uranium, Corrected for % Gd2O3 Content:%U,Corrected5 %U120.01!%Gd2O3!#(4)11.4 Precision and Bias:11.4.1 Percent Uranium UncertaintiesPercent uranium was determined on 29 NBL-125 UO2 standards by five oper
44、ators inone laboratory over a two month period, using a single spectrometric measurement for total impurities (%I) and a single measuredvalue for atomic weight (AW). The certified value of the standard is 88.079 % uranium. The bias was + 0.005 % (absolute), withan average result of 88.0841 %. The pr
45、ecision was 0.0004 % (1 s.d.).11.4.2 O/U and O/M UncertaintiesCertified NBL, or equivalent, standards for O/M and O/U are not available. The O/M ratiowas determined on 27 working UO2-Gd2O3 standard pellets over a two month period by five operators in one laboratory. Thenominal value of the standard
46、pellets which were made by equilibrating a batch of 8 % Gd2O3 production pellets, is 2.000. Theaverage result of 2.0002. The precision was 0.0002 (1 s.d.). The bias from the nominal value is not statistically significant.11.4.3 Sampling and Impurities Measurement UncertaintiesThe uncertainties assoc
47、iated with sampling and measurement ofimpurities are not included in the precision and bias information in 10.4.111.4.1 and 10.4.211.4.2. Uncertainties associated withdetermination of values for % Gd2O3 and % U-235 are negligible.11.4.4 Equilibration Procedure UncertaintiesUncertainties associated w
48、ith the equilibration procedure, such as weighingerrors, furnace temperature, gas composition, gas flow, and pure gas humidity are included in the 10.4.111.4.1 and 10.4.211.4.2data. These errors, however, will vary with equipment and the laboratory environment. Each laboratory should perform its own
49、precision and bias evaluation.12. Keywords12.1 atmospheric equilibration; equilibration; oxygen to metal; oxygen to uranium; uraniumAPPENDIXES(Nonmandatory Information)X1. MODEL FOR NONSTOICHIOMETRY OF URANIA-GADOLINIAX1.1 A thermodynamic analysis of the published oxygen potential data for urania-lanthanide solutions gives a set of equationsrelating the atmospheric oxygen potential at which a solid solution specimen neither gains or loses oxygen, to the specimencomposition (lanthanide content and O/M) and temperature. The oxygen p
