In spent nuclear fuel (SNF), the micron- to nano-sized epsilon phase (Mo-Ru-Pd-Tc-Rh) is an important host of {sup 99}Tc which has a long half life (2.13 x 10{sup 5} years) and can be an important contributor to dose in safety assessments of nuclear waste repositories. In order to examine the occurrence and the fate of the epsilon phase during the corrosion of SNF over long time periods, samples of uraninite from the Oklo natural reactors ({approx}2.0 Ga) have been investigated using transmission electron microscopy (TEM).

Citation: Utsunomiya, S., and Ewing, R.C. United States. Oak Ridge National Laboratory. The Fate of the Epsilon Phase in UO2 of the Oklo Natural Fisson Reactors. Washington, D.C.: Department of Energy, 2005.

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