Fukushima I Nuclear Power Plant (福島第一原子力発電所, Fukushima Dai-Ichi Genshiryoku Hatsudensho?, Fukushima I NPP)
Since September 2010, Unit 3 has been fueled by mixed-oxide (MOX) fuel, rather than the low enriched uranium (LEU) used in the other reactors.[3][4] Units 1–5 were built with Mark I type (light bulb torus) containment structures, Unit 6 has a Mark II type (over/under) containment structure.
Mixed oxide, or MOX fuel, is nuclear fuel containing more than one oxide of fissile or fertile materials. Specifically, it usually refers to a blend of oxides of plutonium and natural uranium, reprocessed uranium, or depleted uranium (eg 7% Pu, 93% U) which behaves similarly (though not identically) to the low-enriched uranium oxide fuel for which most nuclear reactors were designed. MOX fuel is an alternative to low enriched uranium (LEU) fuel used in the light water reactors that predominate nuclear power generation.
One attraction of MOX fuel is that it is a way of disposing of surplus weapons-grade plutonium, which otherwise would have to be disposed as nuclear waste, and would remain a nuclear proliferation risk.[1] However, there have been fears that normalising the global commercial use of MOX fuel and the associated expansion of reprocessing will itself lead to greater proliferation risk.