Integral Fast Reactor - Efficiency and Fuel Cycle

Efficiency and Fuel Cycle

The goals of the IFR project were to increase the efficiency of uranium usage by breeding plutonium and eliminating the need for transuranic isotopes ever to leave the site. The reactor was an unmoderated design running on fast neutrons, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel).

Compared to current light-water reactors with a once-through fuel cycle that induces fission (and derives energy) from less than 1% of the uranium found in nature, a breeder reactor like the IFR has a very efficient (99.5% of uranium undergoes fission) fuel cycle. The basic scheme used pyroelectric separation, a common method in other metallurgical processes, to remove transuranics and actinides from the wastes and concentrate them. These concentrated fuels were then reformed, on site, into new fuel elements.

The available fuel metals were never separated from the plutonium, and therefore relatively difficult to use in nuclear weapons. Also, plutonium never had to leave the site, and thus was far less open to unauthorized diversion.

Another important benefit of removing the long half-life transuranics from the waste cycle is that the remaining waste becomes a much shorter-term hazard. After the actinides (reprocessed uranium, plutonium, and minor actinides) are recycled, the remaining radioactive waste isotopes are fission products, with half-life of 90 years (Sm-151) or less or 211,100 years (Tc-99) and more; plus any activation products from the non-fuel reactor components. (Tc-99 and Iodine-129 are also candidates for nuclear transmutation to stable isotopes by neutron capture.)