Yeah I'm always surprised at how many people don't grasp that the big reactor cooling systems are run off the electrical grid. And backup is usually diesel generators. (And then next backup is batteries, IF the company decided another level of safety was worth the trouble and expense). So if the grid is down (likely in Russian attacks), and a missile happens to take out the generators, you are looking at potential disaster. And, even if the plant was shut down shortly before, there's the problem they call decay heat, which is just intermediate radioisotopes with a short half-life still cranking out heat in the fuel rods and this still requires the coolant pumps to be running for several days or weeks.
The new generation of modular reactors with passive emergency cooling are much safer, especially in a crazy world with bad actors. They still have the waste problem, of course.