Neutronic Analysis of a Plutonium Burner PWR Partially Fed with Inert Matrix Fuel

The plutonium coming from dismantled warheads and that already stockpiled coming from spent fuel reprocessing have raised many concerns related to proliferation resistance, environmental safety and economy. The option of disposing of plutonium by fission has been discussed and many proposals for plutonium burning in a safe and economical manner have been put forward. The advantages of utilizing the pressurized water reactors (PWRs) for plutonium disposition are the well developed and reliable technology and their diffusion. The mixide-oxide (MOX) fuel form, that is used for plutonium recycling in power reactors, is well developed. Nevertheless, to eliminate the production of additional plutonium during irradiation, an improved design fuel was analysed, which replace the natural or depleted uranium with inert oxides. This type of fuel offers the potential for annihilation of the major portion of the plutonium: commercial PWRs operating in a once-through cycle scheme could burn more than 98% of the loaded Pu-239 and more than 73% of the overall initially loaded reactor-grade plutonium. The plutonium still left in the spent fuel was quality-poor and then offered a better proliferation resistance. Power peaking problems could be faced with the adoption of burnable absorbers: zirconium diboride coating in the form of integral fuel burnable absorber (IFBA) appeared particularly suitable. In spite of a reduction of the overall plutonium loaded mass by a factor 3.7, there was not evidence of an increase of the Minor Actinides radiotoxicity after a time period of about 25 years.