[en] In the framework of plutonium multirecycling studies, several scenarios have been studied, including advanced reactor concepts (HM-PWR, CAPRA) as well as advanced fuels or solutions using existing reactor systems. These theoretical recycling scenario studies have shown plutonium degradation during multiple recycling, which in turn lead to an increase in the plutonium content and a worsening of the reactivity coefficients. This effectively imposes a limit on the recycling capabilities due to the requirement to satisfy the safety criteria. This limit to the recycling is strongly linked to the concepts of reactors. Fast reactors or HM-PWR present favourable characteristics. Another way of improvement is on the fuel itself in a standard PWR. The aim is to limit the plutonium content in the reactor in order to get acceptable reactivity coefficients. Thus, an extreme case, shown in the previous scenarios studies, is a complete dilution in the park. This paper presents the study realized in order to characterize and optimize this concept in terms of core parameters, transient behaviour and flexibility from a UOX to a MOX loading in a standard P4 PWR. The steps of the study are a sensitivity analysis, a core evaluation and a transient accident analysis. This last part is the most important and must prove the acceptability of the concept. (author)