This is one of the most compelling nuclear plans I've seen. From the sound of it, these would be fine for intermittent power supply
Building a single one wouldn't be cheap, but the modular / standard design can benefit from economy of scale
Er, how does this work? You can't control when wind and solar produce power, so how can you use them to "fill up the demand when necessary"? If anything, using a fluctuating source on top of already fluctuating demand just increases the amount of power storage you need.
A power source that ramps up and down quickly is more convenient than one that ramps up and down slowly, but both are miles more convenient than one which ramps up and down uncontrollably.
For some simulations to help answer when those two options are best:
Hydrogen is cool, but we should also be investing in efficient methane production. AFAICT it's not too hard to make and has immense advantages - existing transport, storage and use infrastructure and market as a heavily traded good. We can use it for most of our energy or carbon needs with today's technology and existing machines with no or easy modifications.
Hydrogen can be more efficient and probably simpler when appropriate but is more finicky, still needs research and will take a lot of time to ramp up.
Biogas is mostly better than fossil, but we should generate methane from H₂O + CO₂ + energy. It would be useful and quick way to achieve energy storage and decarbonization.
"This paper presents a comprehensive techno-economic evaluation of two pathways: one reliant on wind, solar, and batteries, and another also including firm low-carbon options (nuclear, bioenergy, and natural gas with carbon capture and sequestration). Across all cases, the least-cost strategy to decarbonize electricity includes one or more firm low-carbon resources. Without these resources, electricity costs rise rapidly as CO2 limits approach zero. Batteries and demand flexibility do not substitute for firm resources."
Solar does provide a good way to mitigate carbon emissions in the meantime, even if it's role in a fully decarbonized economy is dubious. It's fast to build and makes a good complement for gas plants. Turn off the gas when the solar cells are collecting, and you can save a good deal of emissions.
Solar also has niche use cases that make sense even with nuclear power. Rooftop solar is a good way to offset air conditioning energy use. In this case, the solar energy collected by the panels are intrinsically connected to the power demand of the air conditioning unit. Plus the energy production and energy demand are co-located.
How much would it cost to build nuclear power generation capacity to meet peak demand, vs. building a grid with renewables, long-term transmission and storage? The levelized cost of solar and wind power is way below that of nuclear power (and that difference will become much larger if you're only fully utilizing nuclear power during the daily peak demand), so the question is how much storage and transmission add for renewables.
It also means you have more turbines on site than the reactor needs on its own, so you can add a furnace burning whatever you like (hydrogen, biofuels, synthetic methane), and that handles the days when renewable output is below average.