/diy/ - Do It Yourself

Tube guy here.
Another thing to keep in mind is that concrete helps a lot more against radiation than metal does. The only thing to keep a close eye on (if you intend to use it as a long-term SHTF-style bunker) is that concrete absorbs oxygen like a sponge. In other words, make sure you've coated the walls in latex paint, or some other kind of coating which keeps the concrete from interacting with the oxygen, also make sure that it's ventilated it properly and have more O2 in storage than you need, just in case.