Radiation ProtectionIf the fireball of the weapon touches the ground, the blast is defined as a `ground burst'. In a ground burst, rock, soil, and other material in the area is vaporized and pulled up into the fireball. This debris is uniformly fused with fission products and radioactive residues and becomes radioactive itself. It then falls to the ground as `radioactive fallout'. If the fireball from the explosion does not reach the ground, the blast is said to be an `air burst'. Radiation (except for initial radiation) does not become a factor in an airburst.
Radiation protection is achieved by incorporating the principals of shielding and geometry.
Gamma radiation is a great health problem for a two-week period. Everyone should stay sheltered in a good fallout shelter for two full weeks. If blast is not a consideration, 4 feet of earth cover shielding over the radiation shelter is sufficient to shield from gamma radiation.
Gamma Ray defense is further achieved by building entrances that have the proper length to diameter ratio and incorporating a 90-degree turn at approximately the middle of the shelter. Approximately 90% of the gamma radiation is directed into the ground from the vertical portion of the entrance. As an example, entrances that do not exceed 48 inches in diameter should have the total length of the vertical and horizontal run no less than 20 feet in length with a 90 degree turn at the 10 foot mark. Larger diameter entrances require longer lengths. The other 10% is almost entirely attenuated by the horizontal portion of the entrance.
The threat of exposure to initial nuclear radiation is confined to a radius of about one and one half miles from ground zero and would prove fatal to any unsheltered individuals. However, in hardened underground shelters, such as those that are being built by Utah Shelter Systems, people could survive all nuclear weapons effects, including initial radiation, within ½ mile of a ground burst, and at ground zero of an air burst. Shelters that may be within the initial radiation zone, must have at least 8 ft. of dirt cover and the entrances must be configured with the proper shielding and geometry.
Alpha and Beta radiation will not penetrate through the outside layers of the skin and do not pose a health hazard unless they accumulate internally. If food has been exposed to fallout, great care should be taken to wash the lids before opening canned food, and to wash and peel all exposed fruits and vegetables. Water purification, food preparation, and post war survival will be discussed in another section of this web site. Call us if you have design questions, or need consultation on other aspects of your shelter plans.