【国外标准】 Standard Test Method for Determination of Hydrogen (total from all sources) in Mixed Oxide ((U, Pu)O2) Sintered Pellets by the Inert Gas Fusion Technique Followed by Thermal Conductivity Measurement

5.1 MOX is used as a nuclear-reactor fuel. This test method is designed to determine whether the hydrogen content of the pellets meet the requirements of fuel specification. Examples of these requirements are given in Specification C833. Other requirements may apply based on agreements between the supplier and the customer.5.2 This method is suitable for all sintered MOX pellets containing up to 15 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 hydrogen in the sample. At lower concentrations, the relative uncertainty increases. At hydrogen contents close to the typical hydrogen content specification limit (1.3 μg hydrogen/g U + Pu metal); the combined relative uncertainty at the 95 % confidence level (k = 2) is approximately 30 %.1.1 This test method covers the determination of hydrogen in nuclear-grade mixed oxides of uranium and plutonium ((U, Pu)O2) sintered fuel pellets. This test method is an alternative to Test Method C698 for the determination of moisture in nuclear-grade sintered mixed oxide (MOX) fuel pellets. Test Method C698 describes the detection of moisture in mixed oxides using a coulometric, electrolytic moisture analyzer. Although the main source of H2 in the fuel pellets is moisture, there could be other sources. The MOX pellet Specification C833 specifies a limit for hydrogen from all sources, not only moisture. The inert gas fusion followed by thermal conductivity detector specified in this test method allows for detection of hydrogen from all sources. Therefore, this test method can be used to determine the limit specified in C833.1.2 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 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.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.