Is the thermal efficiency really relevant? I always understood the externalities to drive much of the costs. And even if you're building a mega site with milit

Is the thermal efficiency really relevant? I always understood the externalities to drive much of the costs. And even if you're building a mega site with military defences, you could still build it by having 10 small reactors. If they are cheaper to build "per megawatt" due to economies of scale, you are still ahead.