【国外标准】 Standard Test Method for The Determination of the Oxygen to Metal (O/M) Ratio in Sintered Mixed Oxide ((U, Pu)O2) Pellets by Gravimetry

5.1 MOX is used as a nuclear-reactor fuel. This test method is designed to determine whether the O/M ratio meets the requirements of the fuel specification. Examples for establishing a fuel specification 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 C757.1.1 This practice is an alternative method to Test Method C698 for the determination of the oxygen-to-metal atom ratio (O/M) in sintered mixed oxide fuel (MOX) pellets. The method presented in Test Method C698 is a one-step thermogravimetric method for determining O/M ratio in sintered MOX powders and pellets. As stated in Test Method C698, thermogravimetric methods using a two-step heating cycle are also satisfactory (1, 2).2 The method presented in this test method is a two-step heating cycle method. This test method is applicable to sintered MOX pellets containing up to 10 weight percent PuO2.1.2 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.