Given these assumptions, starting from 1988 EDF decided to implement a 4-batch strategy with a cycle length reduced to 275 equivalent full power days (efpd) with respect to the former 3-batch and 330 efpd strategy. This change allowed for a 12% reduction in the overall fuel cycle cost and for a better fuel utilisation. However, a few years later, the forecast turned out to be inaccurate, with energy demand rising unexpectedly and the nuclear park being at margins only for 2 000 hours per year.