Question about the Glowing Sea (spoilers)

So when I got to the Glowing sea, and more specifically the Crator of Atom, I see a group of nutters, people of the Church of the Children of Atom. They seem to have no care in the world, but how can they survive in such an irradiated area. I have to use rad away every few minutes in my Power Armor, and yet here these guys are, practically soaking in the radiation.

So how do they live there? By the game's own logic, it should be impossible. Unless it has something to do with being in the early stages of becoming a ghoul (and even that I am skeptical about).