It doesn't have 100% nuclear or 100% renewables, that's why it's called an energy mix. Nuclear does play an important role as France has shown time and time again. Compare France's energy mix (70% nuclear, 2% coal) with Germany's (47% renewables, 30% coal). Shutting down nuclear almost always means burning fossil fuels. Remember, these are NPPs that have already been built and can continue to generate electricity for many years to come. Closing them down one reactor at a time can be easily done after renewable capacity is installed to compensate for the closures.

https://environmentalprogress.org/france