15 ToT EEG Poy Parith PoE RP daGtin VE Bebe det 14 13 12 — © ALTITUDE, THOUS OF FEET 11 0.01 0.1 1.0 10 100 YIELD, KT [[] Population safe with l-psi protection ES} Questionable Bes Population safe with 100-psi protection ANS E23) Population unsafe with 100-psi protection Population safe with 30-psi protection Fig. 41 — Altitudes at Which Friendly Commander Could Use Nuclear Warheads of Various Yields for Various Levels of Population Protection exceeds the distance at which people in shelter will exceed an LD, dose in 48 hr (about 4000-r cumulative 2-day dose, at a distance from Gz ranging to 8 miles). It seems clear that basementshelter attenuating radiation by 0.9 is not enough protection for urban dwellers, since they can receive LDs doses before rescue workers, impeded by debris and high radiation dose rates, can reach them. It also seemsclear that the traditional civil defense postattack services will not be possible over most of the attacked area. Since preattack evacuation is neither feasible nor desirable in view of fallout, the only alternative would seem to be large shelters capable of sustaining life for days or weeks and attenuating all radiation effects. In a shelter system postattack measures would consist of working from the inside out (once radiation levels had fallen to tolerable limits) rather than the present civil defense practice of attempting to clear roads into the damagedarea. 56 ORO—R-17 (App B) CONFIDENLAL