What you need is this:
http://www.stormrooms.dupont.com/solution.html
"The StormRoom™ with Kevlar® uses the same material found in bullet-resistant vests that help protect the police and military forces. This storm shelter is the newest innovation from DuPont, a company known for bringing the world miracles of science"
It's Kevlar for your walls. We are planning to use this material to shore up a lab for protection of the control room.