Make reactors consume uranium at a constant rate.
A nuclear reaction is hard to start and stop or scale at a whim.
Nuclear reactors should consume a constant rate of uranium and generate a constant rate of power thus balancing electricity and incentivizing the use of batteries that can charge when systems are idle, solar panels for supplementation, and turning reactors/systems on/off for conservation of energy.
A further, realistic idea is to make the generators use a fuel cell produced from uranium and some other elements which, when inserted into a reactor and turned on, will keep reacting indefinitely until consumed fully or extracted. The spent cells could pose a hazard and be required to be ejected into space with appropriate systems for safety.