An unconventional mixed-oxide (MOX) fuel management concept for a pressurized water reactor core is proposed. Subassembly management (SAM) is an in-out reloading scheme applied within MOX assemblies that are “reconstructed” at each end of cycle. The SAM concept needs only one kind of MOX fuel pin instead of the three pins necessary in the standard MOX fuel management concept; it also leads to better use of plutonium.