Experimental Evaluation of the Radiation Protection Provided by an Earth-Covered Shelter.

摘要

A study was undertaken to determine the protection against fallout radiation provided by an earth-covered shelter. The study indicated that the shelter offered excellent protection from fallout radiation deposited on and around the shelter. This study also added additional data to the research in radiation shielding provided by various structures which is being conducted by the Civil Effects Test Operations, Division of Biology and Medicine, U. S. Atomic Energy Commission. A fallout radiation field was simulated by pumping, at constant speed, a sealed Co60 source through a long length of tubing which was evenly distributed over an area. Radiation measurements were made Inside the shelter by dose-integrating ionization chambers. In general, the results indicated that the protection factor (ratio of the open-field exposure dose rate to the exposure dose rate in the structure) was approximately 5000 in the center of the shelter, increasing to 10,000 to 15,000 along the sides, and decreasing to about 3000 near the ends. Directly below vents the protection factor was found to be approximately 2500 at the 3-ft level. The shelter was a half-round corrugated-steel structure covered by a minimum of approximately 2 ft of earth on the top and 5 to 7 ft of earth on the sides.