MOX fuel
About 30% of the plutonium originally loaded into MOX fuel is consumed by use in a thermal reactor. In theory, if one third of the core fuel load is MOX and two-thirds uranium fuel, there is zero net gain of plutonium in the spent fuel, and the cycle could be repeated; however, there remains multiple difficulties in reprocessing spent MOX fuel. As of 2010, plutonium is only recycled once in thermal reactors, and spent MOX fuel is separated from the rest of the spent fuel to be stored as waste.