The civil and military utilization of nuclear power results in continuously increasing stockpiles of spent fuel and separated plutonium. Since fast breeder reactors are at present not available, the majority of spent fuel discharged from commercial nuclear reactors is intended for direct final disposal or designated for interim storage. An effective form of intermediate plutonium storage is recycling in thermal reactors. Recycling of the recovered plutonium in commercial light water reactors (LWRs) is currently practiced in Belgium, France, Germany, and Switzerland. The number of mixed-oxide (MOX) assemblies reloaded each year in a large variety of reactors demonstrates that plutonium recycling in LWRs has reached industrial maturity. The status of experience gained today at Framatome ANP confirms the reliability of the design codes and the suitability of fuel assembly and core designs. The validation database for increasing exposures of MOX fuel is being continuously expanded. This provides the basis for further extending the discharge exposures of MOX assemblies and for licensing the use of higher plutonium concentrations. Options to support the weapons plutonium reduction programs and for the development of advanced MOX assembly designs are investigated.