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DOE-STD-3028-2000
system is generally a mixture of oxides with a O/U ratio between 2 and 3. Uranium
oxides in this range are considered stable and suitable for storage.
1. The criterion of 0.5 wt % volatiles provides a reasonable balance between the
difficulty of achieving lower volatiles contents (primarily moisture) and the cost (of
both the container and any ancillary impact on storage facility size) of providing a
container that will withstand the overpressure theoretically postulated by a higher
volatiles content. Correlation of the volatiles criterion with bounding pressures in
storage containers is established in Appendix B (Derivation of Pressure Equation)
and other sections of this Appendix.
2. Most of the stored 233U oxide powders were assayed for volatiles content at varying
heating temperatures at the times they were formed, then stored in closed
containers. Testing each batch for volatiles content according to Criterion 6.1.2.3 will
verify if the historic measurements are still reliable. Existing material failing to meet
the 0.5 wt% requirement must then be treated as specified in Section 6.1.2.2 and be
subject to subsequent verification.
3. The stabilization requirements of this Standard accomplish the following primary
objectives:
reduce the residual moisture (volatiles) content to less than 0.5 wt% and similarly
reduce equivalent quantities of species such as hydrates that might produce
pressurizing gases during long-term storage via radiolysis;
minimize potential for water readsorption above the 0.5 wt% threshold; and
stabilize reactive volatile 233U species.
There are also secondary objectives that are desirable, but not absolutely necessary.
If the material is treated to meet a primary objective, then the following secondary
objectives should also be considered:
convert to U3O8
enhance particle size
If the volatiles content cannot be shown to be less than 0.5 wt %, this Standard
specifies that oxide material will be placed in a continuously oxidizing atmosphere at
a material temperature of greater than 750C (1382F) for a minimum of one hour.
20


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