has a role to play as a scaleable demand-responsive source

Nuclear is best used a base load, it scales in the sense that you can build more plants, but the plant output can't be adjusted as rapidly as the tiny natural gas turbine plants, reservoir-storage, battery array, or other sources.

The best use for nuclear output in a surplus phase would be storing the energy (water reservoir pumping, battery arrays, etc.) or expensive wasteful processes (electric steel plant ovens, hydrolysis to generate hydrogen fuel.)