Is this a good book idea?

Actually, that does sound pretty good. The characters are great. Not many people have the character descriptions down first thing, but it's always nice when they do. Are you going to do a lot of research for this? Maybe where they make or made nuclear bombs or where there are some big nuclear plants? And/or a time frame? This could probably be a pretty good one to have set in the past, as long as you make sure people know it's fiction.