Modern Nuclear can load follow, its not as precise as peaker plants but its not too far off. Another cool thing with modern nuclear is you don't have to directly spin the turbines some modern plants are designed to shunt thermal production to thermal batteries (large pile of salt in a tube) which can be more finely throttled allowing the exact amount of power the grid needs at any given moment to be met. They just have to throttle the reactor to keep the Salt boiling. https://www.energy.gov/ne/advanced-reactor-demonstration-projects