Exploiting the plutonium stockpiles in PWRs by using 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 is one of the most widely discussed and many proposals for plutonium burning in a safe and economical manner have been put forward. Due to their diffusion, PWRs appear to be the main candidates for the reduction of the plutonium stockpiles. In order to achieve a high plutonium consumption rate, a uranium-free fuel may be conceived, based on the dilution of PU02 within a carrier matrix made of inert oxides. In this paper, a partial loading of inert matrix fuel in a current technology PWR was investigated with 3-D calculations. The results indicated that this solution has good plutonium elimination capabilities: commercial PWRs operating in a oncethrough cycle scheme can transmute more than 98% of the loaded Pu-239 and 73 or 81% of the overall initially loaded reactor grade or weapons grade plutonium, respectively. The plutonium sti11 left in the spent fuel was of poor quality and then offered a better proliferation resistance. Power peaking problems could be faced with the adoption of burnable absorbers: IFBA seemed to be particularly suitable. In spite of a reduction of the overall plutonium loaded mass by a factor 3.7 or 5.4 depending on its quality, there was no evidence of an increase of the Minor Actinides radio toxicity after a time period of about 25 years.