Attacked for what purpose? Reactor fissionable material can't be used to make bombs.

Anyway, if being attacked is a possibility, physical security for such plants isn't a hard problem.

> if they’re attacked

Between blowing up an SMR and blowing up any number of modern chemical plants, I’d rather be downwind of the former. We don’t keep huge amounts of fissile material in modern reactor cores.

If French nuclear power plants are getting bombed, then France is in a full scale war. Since they have nuclear weapons I think the limited radioactivity from power plant bombing will be a minor problem compared to mushroom clouds over large cities. So people not realize large nuclear arsenals still exist?