ASTM C696-99(2005)

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 C 753 and C 776.

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

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

3.1.3 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’specifications.

3.1.4 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).

1.1 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade uranium dioxide powders and pellets to determine compliance with specifications.

1.2 This test method covers the determination of uranium and the oxygen to uranium atomic ratio in nuclear-grade uranium dioxide powder and pellets.

1.4 This test method covers the determination of chlorine and fluorine in nuclear-grade uranium dioxide. With a 1 to 10-g sample, concentrations of 5 to 200 g/g of chlorine and 1 to 200 μg/g of fluorine are determined without interference.

1.5 This test method covers the determination of moisture in uranium dioxide samples. Detection limits are as low as 10 μg.

1.6 This test method covers the determination of nitride nitrogen in uranium dioxide in the range from 10 to 250 μg.

1.7 This test method covers the spectrographic analysis of nuclear-grade UO2 for the 26 elements in the ranges indicated in Table 2.

1.8 For simultaneous determination of trace elements by plasma emission spectroscopy refer to Test Method C 761.

1.9 This test method covers the spectrochemical determination of silver in nuclear-grade uranium dioxide. The relative standard deviation is 15 % for the concentration range of 0.1 to 50 μg/g.

1.10 This procedure is designed for a rapid determination of surface area of nuclear-grade uranium dioxide (UO2) powders. The determination of surface area by this procedure is automatic, simple, and fast enough to be used in quality control work. The range of analysis is from 1 to 1500 m²/g.

1.11 This test method covers the determination of hydrogen over the range from 0.05 to 100 μg of hydrogen (H2) in uranium dioxide UO2 pellets by inert gas fusion.