4.1 Uranium dioxide is used as a nuclear-reactor fuel. In order to be suitable for this purpose, the material must meet certain criteria for uranium content, stoichiometry, isotopic composition, and impurity content. These test methods are designed to show whether or not a given material meets the specifications for these items as described in Specifications C753 and C776.

4.1.1 An assay is performed to determine whether the material has the minimum uranium content specified on a dry weight basis.

4.1.2 The stoichiometry of the oxide powder is useful for predicting its sintering behavior in the pellet production process.

4.1.3 Determination of the isotopic content of the uranium in the uranium dioxide powder is made to establish whether the effective fissile content is in compliance with the purchaser's specifications.

4.1.4 Impurity content is determined to ensure that the maximum concentration limit of certain impurity elements is not exceeded. Determination of impurities is also required for calculation of the equivalent boron content (EBC).

4.1.5 Determination of the oxygen-to-uranium ratio is performed on the completed pellets to determine whether they have the appropriate stoichiometry for optimal performance during irradiation.