The problem is that nuclear reactors are huge so you're never going to build that many of them compared to wind turbines (thousands) or solar panels (millions).

France plans to build a series of six reactors for its EPR2 programme with each reactor scheduled for completion 1-2 years apart, but that is only expected to reduce costs by 30% compared to the (hugely expensive) EPR.

Small modular reactors hope to improve things but it's far from clear they will end up any cheaper. Historically making reactors bigger makes them more efficient. The Rolls Royce SMR is just under 1/3rd of the size of the EPR so even if successful any cost reductions are not likely to be dramatic.