Nuclear energy - Isotopic analysis of uranium hexafluoride - Double-standard gas-source mass spectrometric method

Isotopic measurements of uranium isotopes are of great importance to the uranium enrichment facilities, not only for an accurate determination of the 235U enrichment, but also for a determination of the minor isotopes 234U and 236U. This International Standard specifies a method of isotopic analysis of uranium hexafluoride (UF6) with 235U concentrations less than or equal to 5 % by mass and 234u and 236U concentration between 0.001 % by mass and 1.5 % by mass. The method is in routine use to determine conformance to UF6 specifications. Uranium hexafluoride is a basic material to prepare nuclear reactor fuel. To be suitable for this purpose, the material must meet criteria for isotopic composition. This International Standard is applicable if the mass spectrometer uses Faraday cups. This method describes the measurement of the isotopes directly from the process gas UF6. The method can be used for the measurement of samples, but also for on-line measurements