Studies conducted in 1953 using animal subjects in drone aircraft had previously shown that it would be safe for manned aircraft to enter atomic clouds relatively soon after detonation. Penetrations of clouds from low-yield detonations were made during Operation TEAPOT in 1955. Penetrations of the larger clouds from high-yield detonations were made during Operation REDWING in 1956. Special radiation exposure limits, in excess of the usual 3.9 roentgens maximum permissible exposure limit, were established for some of these flight crews.
During Operation TEAPOT, four Air Force officers were permitted to receive up to 15 roentgens, and two received this amount. Exposures of up to 25 roentgens were permitted during Operation REDWING, but no one received this amount. The largest exposures were approximately 15 roentgens for three officers.
Pre- and post-mission urine tests and evaluation in whole-body counters showed no significant internal deposition of fission products or unfissioned plutonium. This work was supported by the U.S. Atomic Energy Commission. (This experiment was referenced in the Markey report and included in The DOE Roadmap of February 1995)
Headquarters Field Command. Manned Penetration of Atomic Clouds. Report of Operation TEAPOT Project 2.8a. Armed Forces Special Weapons Center, WT-1156. Reynolds Electrical and Engineering Co., Inc., Coordination and Information Center, Las Vegas, NV, CIC Document 12800.
Headquarters Field Command. The Radiation Hazards to Personnel Within an Atomic Cloud. Report of Operation UPSHOT/KNOTHOLE Project 4.1. Armed Forces Special Weapons Center, WT-743. Reynolds Electrical and Engineering Co., Inc., Coordination and Information Center, Las Vegas, NV, CIC Document 40992.