Uranium hexafluoride used to produce nuclear-reactor fuel must meet certain criteria for its isotopic composition. This test method may be used to help determine if sample materials meet the criteria described in Specifications C 787 and C 996.

1.1 This is a quantitative test method applicable to determine the mass percent of uranium isotopes in uranium hexafluoride (UF₆) samples. This method as described is for concentrations of ²³⁵U between 0.1 and 10 mass percent, and ²³⁴U and ²³⁶U between 0.0001 to 0.1 mass percent.

1.2 This test method is for laboratory analysis by a gas mass spectrometer with a multi-collector.

1.3 This standard complements C 761, sections 35 through 40, the double-standard method for gas mass spectrometers using a single collector, by providing a method for spectrometers using a multi-collector.

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.