There actually have been many months without more than half of nuclear reactors in France in 2022 - beginning 2023. And in France there are not enough different energy sources to compensate.
https://www.france24.com/en/france/20220825-france-prolongs-...
Taking down such reactors is a periodically routine for maintenance. The question is only how fast you can bring them up again (especially in case of serious repair needs).