CHAPTER 1 INTRODUCTION 1.1 OBJECTIVE The objective of this project was to measure the radiation dose and dose rate one would experisnce in flying through the cloud resulting from a megaton-range weapon and some factors affecting personnel safety in the event of an operational situation requiring flights through such clouds. Specific information was sought on the radiation dose rates inside the cloud, the total dose received in flying through such a cloud, the total dose received on ths return flight after flying through the cloud, and the conditions of flight inside the cloud. This information is needed by the operational commands of the Air Force in their planning to insure the mst-effective utilization, consistent with crew safety, of aircraft in cloud areas. 1.2 BACKGROUND AND THEORY During Operation GREENHOUSE the first significant data on gamma dose rates within atomic clouds were collected. These are reported in Reference 1, The data were collected by drone aircraft flown through the clouds from weapons ranging in yield and at tins of from 3 to 25 minutes after detonation. [feference 1 shows average gemma dose rates within the cloud to be of the orders of 10% r/br from 3 to 5 minutes after detonation and 350 r/br at 20 minutes after detoration. Further measurements of gamma dose rates within atomic clouds wre made in Operation UPSEOT-KNOTHOLE and reported in Reference 2, LDoserate~measuring instruments were mounted in paracimte-borze canisters, and the dose-rate instrments previously used by the Naval Radiological Defense Laboratory (NRDL) in Operation GREENHOUSE (Reference 1) were mounted in QF-80 drone aircraft. Both the canisters and the QF-90's passed through only the head, or mushroom, of the clouds resulting from Yoon ranging in size. Dose rates of the order of 10* r/br were measured from 2 to 6 mimutes after detonation, A compilation of the GAZENHOUSE and UPSHOT-KNOTHOL2 average dose rates as a function of tim after detonation is presented graphically in Reference 2, These points are also included in Figure 3.2 of this report. The time after detonation for each point is the approximate time after detonation at which the airplane or canister entered the cloud. A least-square analysis of the data showed that the best-fit line had the equation: , “32 COPY AS BEST AY AL 1