welve large-diameter bur' d conduit sections of various shapes were tested in th 60-to-149d p s i overpressure region o h b P r i s c i l l a to make an empiricai determination of the degree of personnel protection afford d by commercially available steel and concrete conduits a t depths of burial of 5, 7.5, and 10 feet below grade. Essentially, it was desired to assure that Departmgnt of Defense Class I (100-psi and comparable radiations) and Class I1 (50-psi and comparable radiations) protection is afforded by use of such conduits of various configurations. Measurements were made of free-field overpressure at the ground surface above the structure; pressure inside the structures; acceleration of each structure; deflection of each structure; dust inside each structure; fragmentary missiles inside the concrete structures; and gamma and neutron radiation dose inside each structure. All buried conduit sections tested provided adequate Class I protection (100-psi overpressure and comparable radiation protection) for the conditions under which the conduits were tested. Standard 8-foot concrete sewer pipe withstood 126-psi overpressure without significant damage (minor tension cracks observed) ; standard 10-gage corrugated-steel 8-foot circular conduit sections withstood 126-psi overpressure without significant damage; and standard 10-gage corrugated-steel cattle-pass conduits withstood 149-psi overpressure without significant damage.

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To improve existing knowledge on gamma and neutron shielding properties of shelters. ABSTRACTAn analytical approach is developed to permit determination of gamma radiation attenuation as it passes through two-legged rectangular ducts and shelter entranceways.The approach used employs the albedo concept for wall scattering and includes correction terms necessary to account for the "corner lip effect." With appropriate simplifying assumptions, moderately simple engineering formulas are obtained. Actual use of the formulas requires better knowledge of differential angular albedo than is presently available; however, by assuming isotropic distribution of the albedo function, a very good comparison of experimental information with results calculated by this technique is obtained.

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