Feasibility Study of a Proliferation-Resistant Fuel Form for Plutonium Recycling

A feasibility study of a proliferation-resistant fuel form for commercial power reactors was conducted. An increase in ²³⁸Pu is known to increase the heat load in pure plutonium metal. At high ²³⁸Pu concentrations in spent fuel, the heat load in the plutonium may be sufficiently high that it will be less desirable for weapons production. An actinide-based fuel is proposed that will increase the ratio of ²³⁸Pu/²³⁹Pu in spent fuel, leading to a fuel form resistant to diversion for weapons use. Two actinides were considered, ²³⁷Np and ²⁴¹Am, for seeding in low-enriched (3% ²³⁵U) uranium oxide fuel. The ORIGEN point depletion code was utilized to calculate time-dependent spent-fuel concentrations of ²³⁸Pu, ²³⁹Pu, ²³⁷Np, ²⁴¹Am, and other nuclides of interest. The preliminary results show that both ²³⁷Np and ²⁴¹Am in small quantities generate significant ²³⁸Pu in spent fuel, and more importantly, both actinide-based fuels shift the ²³⁸Pu/²³⁹Pu ratio significantly higher at relatively small initial concentrations. Based on a closed-loop actinide-fuel life cycle study, a ²³⁷Np-based fuel cycle seems much more sustainable as compared to ²⁴¹Am. However, ²⁴¹Am addition to ²³⁷Np-based fuel may have benefits in reducing the end-of-cycle deficit of ²³⁷Np.