THE RELATIVE EFFECTIVENESS OF STRUCTURES AS PROTECTION FROM GAMMA RADIATION FROM CLOUD AND FALLOUT SOURCES AS A FUNCTION OF SOURCE ENERGY (POINT-KERNEL, INFILTRATION, BUILD UP)

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. 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. This information is well known only for a few gamma ray spectra, such as that from weapon fallout. The research reported here transfers the knowledge gained from the previous weapon fallout shielding work to realistic protection factors for possible accidental releases whatever the released spectrum might be.;The results show that the protection provided by houses for the PWR-2 event is approximately equal to that for the 1-hr weapon fallout. However there are significant differences for other spectra, such as the release from Three Mile Island. The effects of varying building size and wall thickness are reported as well as the relative importance of both cloud and fallout sources that infiltrate into structures.;This work should influence the decisions made to evacuate or seek shelter in the event of a radioactive release.;Point kernel models were developed for both the fallout and cloud sources. That development included a method of accurately combining buildup factors in multi-region problems over wide ranges of energy and photon mean free path. A generalized method for calculating the effect of ground roughness on the attenuation factor for fallout sources was also developed. The results were reported for for the 1-Hr. weapon fallout, Reactor Safety Study PWR-2 cloud and fallout, SL-1 fallout and TMI-2 cloud and fallout spectra as well as for discrete energies from 15 KeV to 15 MeV. The structures given as examples include small wood frame and large brick houses.