【国外标准】 Standard Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Mixed Oxides ((U, Pu)O2)

4.1 Mixed oxide, a mixture of uranium and plutonium oxides, is used as a nuclear-reactor fuel in the form of pellets. The plutonium content may be up to 10 weight %, and the diluent uranium may be of any 235U enrichment. In order to be suitable for use as a nuclear fuel, the material must meet certain criteria for combined uranium and plutonium content, effective fissile content, and impurity content as described in Specification C833.4.1.1 The material is assayed for uranium and plutonium to determine whether the plutonium content is as specified by the purchaser, and whether the material contains the minimum combined uranium and plutonium contents specified on a dry weight basis.4.1.2 Determination of the isotopic content of the plutonium and uranium in the mixed oxide is made to establish whether the effective fissile content is in compliance with the purchaser's specifications.4.1.3 Impurity content is determined to ensure that the maximum concentration limit of certain impurity elements is not exceeded. Determination of impurities is also required for calculation of the equivalent boron content (EBC) as described in Practice C1233.4.2 Fitness for Purpose of Safeguards and Nuclear Safety Applications—Methods intended for use in safeguards and nuclear safety applications shall meet the requirements specified by Guide C1068 for use in such applications.1.1 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade mixed oxides, (U, Pu)O2, powders and pellets to determine compliance with specifications.1.2 The analytical procedures appear in the following order:  SectionsUranium in the Presence of Pu by Potentiometric Titration   2Plutonium by Controlled-Potential Coulometry   2Plutonium by Amperometric Titration with Iron (II)   2Nitrogen by Distillation Spectrophotometry Using Nessler Reagent  8 to 15Carbon (Total) by Direct Combustion-Thermal Conductivity  16 to 26Total Chlorine and Fluorine by Pyrohydrolysis  27 to 34Sulfur by Distillation-Spectrophotometry  35 to 43Moisture by the Coulometric, Electrolytic Moisture Analyzer  44 to 51Isotopic Composition by Mass Spectrometry   3Rare Earths by Copper Spark Spectroscopy  52 to 59Trace Impurities by Carrier Distillation Spectroscopy  60 to 68Impurities by Spark-Source Mass Spectrography  69 to 75Total Gas in Reactor-Grade Mixed Dioxide Pellets    4Tungsten by Dithiol-Spectrophotometry  76 to 84Rare Earth Elements by Spectroscopy  85 to 88Plutonium-238 Isotopic Abundance by Alpha Spectrometry   5Americium-241 in Plutonium by Gamma-Ray SpectrometryUranium and Plutonium Isotopic Analysis by Mass Spectrometry  89 to 97Oxygen-to-Metal Atom Ratio by Gravimetry  98 to 1051.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (For specific safety precaution statements, see Sections 6, 13.2.5, 41.7, and 93.6.1.)