A cermet waste package may improve the long-term performance of the YM repository by two mechanisms: reducing (1) the potential for nuclear criticality in the repository and (2) the long-term release rate of radionuclides from the waste package.

In the natural environment, the centers of uranium ore deposits have remained intact for very long time periods while the outer edges of the ore deposit have degraded. A cermet waste package may operate in the same way. The sacrificial, slow degradation of the waste package and the DU oxide protects the SNF uranium dioxide in the interior of the package long after the package has failed.

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