Plutonium Burning in Pressurized Water Reactors Via Nonfertile Matrices

The plutonium that comes from dismantled warheads and that is already stockpiled from commercial fuel reprocessing has raised many proposals for its burning in a safe and economical manner. The utilization is examined of current pressurized water reactors (PWRs) that are partially fed with a nonfertile oxide-type fuel, while the rest of the core is still fed with standard ²³⁵U-enriched fuel. The unconventional fuel consists of PuO₂ diluted in an inert matrix, which should be highly radiation resistant, scarcely neutron absorbent, and chemically stable and which allows the final disposal of the discharged fuel without any treatment. Commercial PWRs operating in a once-through cycle scheme can transmute 97 to 99% of²³⁹Pu and 71 to 84% of total initially loaded reactor- and weapons-grade plutonium, respectively. The remnant plutonium is in a proliferation-resistant condition. The high initial reactivity of the plutonium-bearing rods causes a high initial rod power peak and continuously decreasing power generation in these rods during the irradiation. A less pronounced rod power peak in UO₂ rods at end of life has to be addressed. The reactivity coefficients are, in absolute terms, slightly lower than the standard UO₂ fuel ones.