CHAPTER 4 CONCLUSIONS AND RECOMMENDATIONS 401 - CONCLUSIONS Twenty-seven penetrations of ES«10.1: from multimsgaton-yield detonations were a 8 ranging from 20 to 73 minutes after detonation and at altitudes ranging from 20,000 to 50,000 feet. Sixteen of these penetrations wre earlier than 45 minutes after detonation, and seven were earlier than 30 minutes. All penetrations made earlier than 45 minutes were bore~throughs in which the aircraft completely traversed the cloud from one side to the other at the penetrating altitude. Fenetrations were made through clouds from air, land~ surface, and water-surface detonations. Maximdose rates as high as 800 r/hr were encountered in some of the early penetrations, and several flights yielded total radiation doses to the crew of 15 r (meas- ured by film badges) and 35 to 40 r (measured by instrumentation mre Sensitive to soft radiation). Data collected on these flights and in conjunction with past Studies of conditions prevailing within clouds from nuclear detonations warrant a number of conclusions regarding the feasibility of flying through such clouds at relatively early times after detonation: The average and maximum external gamma-radiatioa dose rates in the mushroom of the cloud from nuclear detonations are dependent on the penetration tims and the fission-to-total-yleld ratio of the detonation and are indspendent of the yield of the detonation, The average radiation dose rate in the mushroom of the cloud from a 100-percent-fissionyield detonation as a function of time from 3 to 80 minutes after detonation is given by the equation: D=1,0 x 105t7l-? Wheres (401) D = Average dose rate, r/hr. t = Tims after detonation, minutes, This average dose rate, D, may vary by as mich as a factor of two for any given penetration, Beyond 1 hour after detonation, when the mushroom begins to be dispersed by the winds, a more-rapid decay of the radiation dose rate in -_ -.-- the cloud is noted in which the slope may be as great as -3 or -4, The radiation dose rate in the stem beneath the mushroom of clouds from water~surface or air detonations is less by a factor of five to ten than in the mushroom itself, 34 BEST AVAILABLE COPY Ce