France’s nuclear fleet performs load following but it is harder on the steam mechanicals requiring more frequent maintenance. The question is if this operating model is more cost efficient versus lithium and sodium battery storage at scale for buffering generation and load, with battery storage around $52/kWh for fully integrated systems currently (LFP chemistry). They're constantly burning ~1GW of fossil gas that could potentially be replaced with grid forming battery storage, assuming nuclear output is increased.
Besides domestic battery storage, an additional challenge is that they’re transmission constrained and there is too much nuclear and renewables and insufficient battery storage for domestic demand. Additional inteconnector capacity is coming online to Ireland in 2026 though (Celtic Interconnector, 700MW HVDC submarine cable).