Overhead and Entranceway Radiation Doses

Shielding: Any material or obstruction that absorbs or attenuates radiation and thus tends to protect personnel or materials from the effects of a nuclear explosion. A moderately thick layer of any opaque material will provide satisfactory shielding from thermal radiation, but a considerable thickness of high-density material may be needed for nuclear radiation shielding, especially for neutron radiation shielding. NORAD S-Series fallout shelters are rated at 10 psi with 72 inches of earth over the crown of the shelter ceiling.

How to Read this Table

Dist. GZ: Distance from Ground Zero
MSD: Minimum Survival Distance

Example: Referring to the table, a shelter located in the 8 psi range or one mile downwind of a one-hundred-KT surface burst weapon would be exposed to a gamma radiation dose on the ground of 10,054 rems. A shelter at this location with thirty-six inches of earth cover (thirty-three inches is the closest conservative number) would result in a radiation dose of 170 rems to people inside the shelter. People receiving this dose would suffer radiation sickness within two to three hours. Most people would survive if they are in good health at the time. The established maximum radiation dose inside an underground shelter is twenty-five rems from all radiation sources for the first thirty days following the detonation.

GAMMA AND NEUTRON RADIATION DOSES COMBINED IN REMS INSIDE A SHELTER BASED ON EARTH COVER
100 KT SURFACE BURST
Dist. GZ MSD 0.5 MI 0.6 MI 0.7 MI 0.8 MI 0.9 MI 1 MI 10 MI 25 MI 50 MI 100 MI
Overpressure psi 200 30 21 15 12 10 8 0 0 0 0
Initial Gamma rems 25,000 25,000 10,000 4,500 2,000 1,200 500 0 0 0 0
Fallout Gamma rems 9,554 9,554 9,554 9,554 9,554 9,554 9,554 5,800 3,800 375 100
Neutron rems 1,000,000 80,000 25,000 15,000 7,000 4,000 1,600 0 0 0 0
Earth-inch                      
5.5 517,277 57,277 22,277 14,527 9,277 7,377 5,827 2,900 1,900 188 50
11.0 258,639 28,639 11,139 7,264 4,639 3,689 2,914 1,450 950 94 25
16.5 129,319 14,319 5,569 3,632 2,319 1,844 1,457 725 475 47 13
22.0 64,660 7,160 2,785 1,816 1,160 922 728 363 238 23 6
27.5 32,330 3,580 1,392 908 580 461 364 181 119 12 3
33.0 8,353 1,165 501 337 236 199 170 91 59 6 2
38.5 4,176 583 251 169 117 100 85 45 30 3 1
44.0 2,088 291 125 84 59 50 42 23 15 1 0
49.5 1,044 145 62 42 30 25 22 11 7 1 0
55.0 522 73 31 21 14 13 11 6 4 0 0
60.5 261 37 16 11 8 6 5 3 2 0 0
66.0 69 18 7 5 3 3 2 1 1 0 0
71.5 35 6 3 2 1 1 1 1 0 0 0
77.0 17 3 1 1 1 1 1 0 0 0 0
82.5 9 2 1 0 0 0 0 0 0 0 0
88.0 5 1 0 0 0 0 0 0 0 0 0
93.5 2 0 0 0 0 0 0 0 0 0 0
99.0 0 0 0 0 0 0 0 0 0 0 0
104.5 0 0 0 0 0 0 0 0 0 0 0
110.0 0 0 0 0 0 0 0 0 0 0 0
115.5 0 0 0 0 0 0 0 0 0 0 0
121.0 0 0 0 0 0 0 0 0 0 0 0
PRINCIPLES OF PROTECTION, The US Handbook of NBC Weapons Fundamentals and Shelter Engineering Design Standards, 6th edition, 2013, Walton McCarthy M.E. Brown Books.
Effects Rems
50% Lethal 200-450
radiation sickness 50-200
blood effect 25-50
safe 0-25