Radiation Exposure Received During Return to Base Although the above illustrated that fighter-type aircraft were capable of collecting the desired samples from two explosions within the acceptable limit for the in-cloud radiation exposure, a complete estimate of capability included additional exposure received while the aircraft was returning to base, During the flight through a cloud some of the radioactive debris | adhered to the exterior surfaces of the sampling aircraft, As a result a radiation flux or "cockpit" radiation background existed within the interior of a sampling aircraft after its departure from the cloud, to base the pilot received additional radiation exposure, While returning Since this exposure decreased that which was available for collecting a sample, it was important to understand what factor contributed to it and to be able to estimate what increases over the in-cloud exposure project personnel might expect under operational conditions, Such an increase was especially significant when the in-cloud exposure was required to be high and the time to return to base of long duration. © To Los Alamos scientists the retention of radioactive material on the surface of the aircraft appeared to depend markedly upon the location of the surface, its state of cleanliness, the mode of airflow over it, and the state of aggregation of the contaminating radioactive debris, While the phenomena involved in the retention of the material were somewhat complex,. all of the surfaces taken together were considered as a collector similar to the filter devices carried by the aircraft. For short flight times in the cloud, therefore, the amount of material adhering after a single cloud penetration was determined by an equation similar to that used for 211 AFWL/KG SWEH-2-003h 2° ~