Increase of minor actinides in spent MOX fuels
This diagram compares the production of minor actinides in PWR reactors using standard uranium fuel (UOX) or in fuel containing 30% MOX and therefore plutonium. The numbers correspond to an annual load for 20 tons of heavy metal (uranium and plutonium). More minor actinides are produced in the MOX fuel, as they can be formed more easily from plutonium nuclei. These minor actinides increase the long-term radiotoxicity of radioactive waste,. This is a disadvantage of MOX fuels.