Coal and nuclear are both inflexible power sources, they are either on or off, and they are hard to turn on and off. Nuclear does have the benefit of being cheap after very high initial capital costs. Natural gas is a much better backup to renewables however, since it can turned on and off at will. Dam hydroelectric also has that nice quality (send water through the generator when you need it, otherwise let it stay in the reservoir).
Given nuclear’s inflexibility, doing untimely work when less electricity is needed for more timely needs is also a win.
I don’t see nuclear making it big any time soon. There’s too much up front costs, but in theory one could make use of any excess heat during off peak hours.
For example desalination, hydrogen production, indoor growing with the light cycle at night or whenever the low demand period is, etc...
For the near future I’d only expect small modular reactors to see much use in areas with unreliable sunlight for chunks of the year. Especially since they could use the waste heat for heating/growing.
Nuclear with hydro/pumped storage is an interesting combo: use the extra nuclear power to pump water up into a reservoir and then when extra energy is needed, move the water down through a turbine. The reservoir is basically a battery in this context.
Waste heat isn’t really recyclable, or it wouldn’t be waste heat :).
To generate electricity you need a hot side and a cool side.
The huge towers on power plants are for cooling the warm (waste) output. If you can get someone to cool your warm waste water even further than the cooling towers would, it would both increase efficiency of electricity generation, and use the boatloads of low grade heat for something useful.
You still need independent cooling capability either way.
Nuclear's inflexibility is not a barrier to countries like France generating over 70% of its electricity from it. Energy demand fluctuations throughout the day are significant but not huge - usually ~20% different from peak to trough.
Nuclear reaction can be slowed down, coal furnace can be used with lower amount of coal at lower temperature.
Nuclear does not need to be turned on or off spontaneously. Nuclear power plant can increase or decrease power smoothly, and that’s practically enough because consumption patterns are easily predicted.
The inflexibility you are describing is nonissue.
High capital cost is. But the largest issue is irrational fears of voters.
But that takes minutes or hours to do. And on anything but 100% power, the fuel innefficiency is bad.
That latter is mostly a problem with coal, but even nuclear is burning fuel and costing wear.
Plants can be optimized to react really fast, or run efficient on lower capacity, or run efficient on max capacity. Choose one.
You're right that power consumption is predictable. But looking at some great-parent posts I'd assume we're still talking about using nuclear as backup for renewable sources.
In this case, often the renewable power production is the bigger variable factor in my opinion, and it's less predictable than usage patterns.
Given nuclear’s inflexibility, doing untimely work when less electricity is needed for more timely needs is also a win.