Homogeneous thorium-plutonium fuels - proliferation risk and potential for plutonium reduction

Significant amounts of plutonium already separated from spent fuel (today 500 t worldwide) pose a proliferation problem that has to be tackled in a sound way. Advanced reactor concepts discuss thorium fuels as alternative to mixed uranium/plutonium oxide (MOX) and inert matrix fuels (IMF) to enable proliferation-resistant disposal of plutonium. Thorium fuels are ascribed special potential to dispose of weapons-usable plutonium since they do not give rise to production of new plutonium as is the case for conventional uranium fuels. On the other hand, employing such fuels leads to production of fissile U-233 that, in principle, is nuclear weapon usable material, therefore constituting a proliferation risk. In comparison with similar previous work for IMF and MOX fuels, we performed MCNP cell burn-up calculations with different homogeneous thorium-plutonium fuels, analysing their potential to dispose of plutonium and the proliferation concern associated with their use.