SCATTERED RADIATION (SKYSHINE) CONTRIBUTION TO A CONCRETE-COVERED BASEMENT LOCATED IN A SIMULATED FALLOUT FIELD.

The report determines, experimentally, the effect of overhead mass thickness on the shielding characteristics of a concrete-walled basement located in a simulated fallout field and compares the results with theoretical calculations set forth in NBS Monograph 42. A uniformly contaminated residual gamma radiation area was simulated to a radius of 600 feet with a cobalt 60 point-source circulation system. Experimental exposure-rate measurements were obtained in the free field and also within a concrete-covered basement as a function of height above the basement floor. Ionization chamber dosimeters were used as radiation detectors. Experimental measurements were extrapolated by analytical procedures to infinite field conditions and divided by the infinite free-field exposure rate measured 3 feet above ground to find the reduction factors. These reduction factors were compared with the theoretical results. (Author)