8/5/2023 0 Comments Beneath a steel sky radiation![]() Comparisons between protection factors from fallout data and MRMU data at the underground group shelter were excellent. This was good, considering the limitations of the two sets of data and other factors affecting the differences. Protection factors from fallout data and mobile radiological measurements (MRMU) at the basement structure compared roughly within a factor of 2. These measurements were compared more » with measurements taken under actual fallout conditions at an earlier time and were also compared with the theoretical calculations. Radiation levels at selected points inside the structures were measured with sensitive ionization- chamber detectors. An idealized fallout radiation field was simulated by the use of a sealed radioactive Co/sup 60/ source that was pumped at a uniform speed through a long length of flexible tubing evenly distributed over the area of interest. The two buildings studied were a lightly constructed building with a basement, and an underground group shelter. « lessĪn experimental study designed to provide a basis for estimating protection against fallout radiation was made on two types of structures at the Nevada Test Site. It was concluded that beta doses must be considered in protecting growing food crops and livestock, and that even minimal shelter to prevent direct surface contamination would be of great importance. The estimated dose for Artemisia was 4449 rads but the reduction in dose by the shelters was nearly sufficient to prevent damage to the shrubs, even though all other Artemisia shrubs in the center of the fallout pattern were killed. Beta doses to the shrubs were still further reduced to 31% of the 25-cm beta dose in the open by shielding the shrubs from direct fallout contamination. ![]() This reduction was attributed to self-shielding. The beta doses to unsheltered vegetation were, however, reduced by almost 50% compared to doses at 25 cm in the open. For shrubs not covered, it was found that the gamma radiation doses were essentially the same as the doses measured in the open and away more » from shrubs but there was a 15% reduction in dose under the sheets. In addition, polyethylene sheets were placed over shrubs to determine whether the shrubs could thus be protected against radiation damage. On the basis of information from two earlier experiments, Palanquin and Cabriolet, special dosimeters for measuring both beta and gamma radiation were placed in the open environment and on shrubs in the downwind area where fallout was anticipated. Project Schooner was a nuclear cratering experiment in the PLOWSHARE Program for peaceful application of nuclear explosives. The structures given as examples include small wood frame and large brick houses. The results were reported for the 1-hr weapon fallout, and TMI-2 cloud and fallout spectra, as well as for discrete energies from 15 KeV to 15 MeV. A generalized method for calculating the effect of ground roughness on the attentuation factor for fallout sources was also developed. That development included a method of accurately combining buildup factors in multi-region problems over wide ranges of energy and photon mean free path. Point kernel models were developed for both the fallout and cloud sources. The research reported here transfers the knowledge gained from the previous weapon-fallout shielding work to realistic protection factors for more » possible accidental releases whatever the released spectrum might be. This information is well known only for a few gamma ray spectra, such as that from weapon fallout. In order to determine what doses the public might receive if they try to evacuate or seek shelter, it is necessary to know how much protection structures such as homes and vehicles provide. In the event of a release of radioactive material, it is necessary to know the doses the public could receive in order to make decisions that minimize the public's risk.
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