Do-it-yourself shelters - Part II : Blast shelters

ABSTRACT

In Part I we discussed the fallout threat and fallout shelters, and we offered some basic information on protection and shelter requirements. It would be a good idea to review Part I before reading Part II. One way to keep the blast and hot wind out of the ventilation system is to use blast valves to close the vents. The construction is concrete and steel. Based on 10 square feet per person, it could hold 6 people. I prefer more room. The overpressure protection is given as 15 psi. The Oak Ridge National Laboratory has been doing some excellent research on how to provide blast protection at prices we can afford. The key is not to build a superfortress but rather to take advantage of some long-known but little-used physical laws that have already been tested. The principle is known as "earth arching", and it states that if the shelter and its entrance closure are capable of "bending but not breaking" and earth fill above is coarse, then a major portion of the downward load will divert to the side and travel into the dirt surrounding the shelter