【国外标准】 Standard Test Method for The Determination of Carbon (Total) Content in Mixed Oxide ((U, Pu)O2) Sintered Pellets by Direct Combustion-Infrared Detection Method

5.1 MOX is used as a nuclear-reactor fuel. This test method is designed to determine whether the carbon content of the pellets meet the requirements of the fuel specification. Examples of these requirements are given in Specification C833.5.2 This method is suitable for all sintered MOX pellets containing up to 12 weight % PuO2 when the UO2 and PuO2 meet the requirements of Specifications C753 and C757. The method uncertainty is related to the concentration of the carbon in the sample. At lower concentrations, the relative uncertainty increases. At carbon contents close to the typical carbon content specification limit (100 μg carbon/g U + Pu metal) the method uncertainty is on the order of 5 %, but exact method performance is difficult to determine due to the lack of matrix matched certified reference material.1.1 This test method is an alternative to Test Method C698 for the determination of carbon in nuclear grade sintered mixed oxide (MOX) fuel pellets. The method for the determination of carbon presented in Test Method C698 consists of combusting carbon contained in MOX pellets with oxygen in a high-frequency induction furnace and detecting the resulting carbon dioxide using a thermal conductivity cell. The method for the determination of carbon presented in this test method consists of combusting carbon contained in MOX pellets with oxygen in a high-frequency induction furnace and subsequent detection of the resulting carbon dioxide (CO2) using a non-dispersive infrared detector (NDIR). Sulfur oxide is stripped from the carrier gas stream by a cellulose filter prior to the detection of CO2.1.2 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 may involve hazardous material, operations, and equipment. 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 consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.