Steel vs icf concrete

We plan and design our bunkers according to guidelines specified by TACDA Academy Civil Defense Basics. See below: 

Underground fallout shelters provide much better protection than basement shelters. Four feet of soil overhead will provide a PF greater than 1000. Good underground fallout shelter entrances should be between 30 and 48 inches in diameter and should have a total length of 22 feet or more. The best attenuation is reached if each leg of the L shaped entrance is 11 feet in length or greater.

Blast shelters should be built with arched ceilings. Flat-topped shelters will not carry the dirt load at those depths, and could fail catastrophically under the additional load from large over-pressures. Shelters in areas near heavy blast targets should be buried at twice their diameter. This depth of cover provides an ‘earth arching’ effect. The full earth arching effect will provide the shelter with approximately 200 psi of overpressure protection. A 10-ft. diameter shelter should be placed into a 20-ft. deep hole. A 9-ft. diameter shelter should be placed into an 18 ft. deep hole. This level of protection provides survivability at 1/2 mile from ground zero of a one-megaton yield ground burst.

The concept of building shelters from corrugated steel tanks was conceived by scientists and engineers at Oak Ridge National Laboratory (ORNL), and actually tested under blast conditions to 200 psi.

This type blast shelter would also provide protection from the ‘initial radiation’ which otherwise is lethal within 1 1/2 mile range of the detonation. Shielding, however, must be placed into the horizontal runs of the entrances to capture the neutrons from the initial radiation. The overhead shielding for initial radiation requires 8 ft. of cover.

Outside of the 1
-mile radius of the blast, initial radiation is not an issue. Residual radiation (fallout) is easily attenuated with as little as 4 ft. of dirt cover overhead.