More EVs (charged at morning and at night) and more renewables, will lead to more volatility on the grid. Meaning the supply of electricity generated will have more variability.

Nuke is really good at producing large swaths of constant energy. However, it is not good at throttling up and down to supply instantaneous demand variability.

In short, nuke is great at producing energy, but more and more, the grid is in need of capacity (ability to flexibly follow load and make electricity at peak demand)