238PuO2, the fuel used in Radioisotope Power Systems for space exploration, undergoes a secondary (a,n) reaction with the naturally occurring 17O and 18O found in the oxide.  This (a,n) is the primary source of worker dose rates and can have a detrimental impact on spacecraft components.  Currently, isotopic exchange with 16O is used to minimize the (a,n) reaction, but the kinetics and mechanism of this reaction are not well understood.  Previous work on CeO2 suggests that the rate limiting step in the oxygen isotopic exchange rate for CeO2 and PuO2 is small polaron hopping (i.e. the movement of Ce3+ through the material), which is very interesting because this suggests that the exchange rate would be independent of the atmospheric composition and the physical characteristics of the PuO2 powder. New experiments to study the oxygen isotopic exchange kinetics and mechanism on 238PuO2 are in the planning stage.  Results from these experiments will be presented and compared to previous PuO2 and CeO2 exchange data in an attempt to determine the full rate law, mechanism, and thermodynamic properties of this reaction.

Isotopic oxygen exchange kinetics and mechanisms with <sup>238</sup>PuO<sub>2</sub>

247th National Meeting (2014)

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Isotopic oxygen exchange kinetics and mechanisms with 238PuO2

Isotopic oxygen exchange kinetics and mechanisms with ²³⁸PuO₂