At the moment, barring magical energy sources that haven't been proven in any meaningful sense, nuclear technology has shown itself to have the fewest long-term consequences and the highest efficiency. However, it is unfortunately also the easiest to point to a few events in history and easily make the layman cast doubt on its safety. It's worth pointing out that the most significant nuclear accident in history took place in the USSR (which wasn't particularly notorious for its safety protocols), on a reactor that had several known design flaws that were ignored, and the only other major accident representing a one in a thousand years perfect-storm that overcame several redundancies.
This concern about "drones" in relation to nuclear power plants is borderline paranoia. Are you concerned about drones dropping bombs or somehow disabling safety systems on a nuclear reactor? Every single nuclear power in the world has nuclear power plants, so they're all equally susceptible to the same attack in the same way that they're all equally capable of responding to said attack- mutually assured destruction as it goes.