Plutonium management and multi-recycling in LWRs using an enriched uranium support

The MIX concept proposes a realistic trade-off between the will to utilize Pu in actual PWRs, and the necessity (for economic reasons) to go toward long cycle lengths and high burnups. Indeed, if burnups around 50 GWd/t have to be reached with MOX, then the Pu content must be around 10% which impairs the control mean efficiency. In the MIX, the Pu content is limited at 4% and the uranium is enriched in order to attain the target burnups; even with a poor quality Pu, the necessary U²³⁵ enrichment is lower than for the UOX core. The core characteristics are presented, as well as the transition from a UOX core to a MIX core, and two accidental configurations (cooling transient and control cluster ejection)