How is overbuilding going to help when the source of the power itself is intermittent? The sun regularly sets and the wind has this unfortunate habit of not blowing. Or, oddly enough, blowing too much.
If we hope to go 100% renewable, storage is a key piece of that puzzle.
Technically yes if you have an entire fleet to both spread the load following across and their manage their fuel cycles since they get less flexible the further into a fuel cycle a reactor is.
Economically? Load following with nuclear power means an even worse business case than running at 100% 24/7. And nuclear power is already a laughably bad business case when running at 100%.
You don't need to change fuel cycles to reduce the output of a nuclear plant. You can accomplish it by more aggressively cooling the water in the steam turbines, effectively wasting heat (and thus generating less power).
Nuclear is a bad business case compared to a fossil fuel grid. Solar and wind backed by fossil fuels are a better business choice, too. But when it comes to a fossil-fuel free grid, it's the only viable option if you don't have a big source of hydropower nearby. Batteries can't deliver the required storage capacity. Remember, the world uses 60,000 GWh of electricity per day. And as transportation and industrial uses of fossil fuels are electrified, that'll increase.
“Oh no we have too much power, what are we going to do with it” is a much better problem to have than “the sun and wind are going down at the same time and we don’t have enough power, what are we going to do about it”.
Don’t piss on my leg and tell me it’s raining. Most of the costs and all of the shutdowns in nuclear power are primarily motivated by anti-nuclear activism. What you’re describing is a policy choice, not an essential reality.
If it costs you money to generate power at a time you cannot sell it, that is losing money. Wind and solar are unique in that they have low marginal costs, whereas a nuclear plant requires more staffing and fuel burn.
Nuclear's electrical output can indeed be turned down, by over-cooling the steam in the turbines. The reactor is putting out the same power, but less electricity is generated since you're deliberately increasing waste heat. This is not efficient so it's rarely done.
Furthermore, too much energy is a far easier problem to solve than too little energy. People can desalinate water, or do any other energy intensive things.
Technically yes if you have an entire fleet to both spread the load following across and their manage their fuel cycles since they get less flexible the further into a fuel cycle a reactor is.
Economically? Load following with nuclear power means an even worse business case than running at 100% 24/7. And nuclear power is already a laughably bad business case when running at 100%.
The fuel is burned at the same rate using this method of modulating output. Thermal output from the reactor is the same. Electrical output is reduced because heat is deliberately wasted.
If we hope to go 100% renewable, storage is a key piece of that puzzle.