If the electrical grid fails and takes years to re-establish, how will the plants cool down?
If they are shut down and there is no grid power, then they would use diesel generators to run the cooling systems, the generator would need refueling every eight hours. If they are operational, they produce more than enough power for the cooling system. A conventional nuclear power plant is at it's most dangerous when shut down which is ironic since most safety protocols demanded of them requires shutting them down whenever there is a slight risk such as what happened at Fukishima, had Fukishima been left on, there would not have been a problem. You could bet that even if the entire grid may take years to rebuild, the nuclear power plants, hospitals and even grocery stores would have priority and would have power very quickly, a grid doesn't have to be completely repaired for portions of it to work. Solar storms are really not a civilization ending threat, merely an inconvenience as it might take some time for the entire grid to be operational again but that does not mean portions of it wouldn't be operational sooner as in days. Of course, conventional solid fuel rod nuclear technology were developed for expediency in producing weapons grade plutonium and the proprietary fuel rods allowed the manufacturers to direct the economic benefits to themselves much as printer manufacturers do with inkjet cartridges. A competing technology called liquid flouride thorium reactors could not melt down, could not explode, could not leak, shuts down safely if cooling power is lost, stays shutdown safely without power, and consumes existing nuclear waste reducing the nuclear wastes to a small amount that only needs to be stored for 350 years instead of the current 30,000 years. The military had no need for it, the government didn't want it because it did not employ an army of technicians, the reactor manufacturers didn't want it as it did not have proprietary nuclear fuel rods.
