The mini-nuke plants cost $1 billion to $2 billion a piece. But we probably wouldn’t need 715 of them. We probably just need 200 hundred, and the industrial capacity to quickly make more.
I want to compliment you for your comments. Only one further suggestion but think you have already thought of this one and that is to bury the lines.
Maybe one other thought ... Since the substations would remain above ground a breaker could be set to trip once the surge came in thereby saving the underground lines.