. 427 = SHUTTER In the delayed shutter exposures, retinal burns, 6 of 16 rabbits sustained The lesions vere produced mostly in cases vhere the exposure included the maximur or near maximum flux of the second pulse. Increments of the flash beyoni 0.6 seconds did not produce burns in this event. sTupTss Burne produced tehind filters at URIAH and VAN at 3.0 and 3,8 miles, respectively, were sixiler in sise anid appearance to blink reflex lesions sustained on 7APTAN (DAVID) at ground sero, distance from VYrom this it is inferred that the filters reduced the Calorie jose and dose rate at URIAR and VAN to a level below that vhioh could produce burns. PROTECTIV? FIF“TRONIC SHUTTERS These shutters were inoperative at H hour due to a fire in the wiring circuit at Ho -4 minutes. With the grid mechanism fully open, the shutter still reduces the incitent visible light by about 60 percent, As a first approximation it {5 estimated that the energy reaching the 9 rabtit eye vas effectively reduced from 2 @ about au’. is of interest that no lesions vere produced in the animals behind the protective shutters, Within the limits imposed by the yiel4 of the weapon and the blink re“lex timo, it would appear that the “hresnaiy burn production ‘or this event lies veer Wt BEST AVAILABLE COPY Ny COM“ LUS IONS The blink reflex time for animals ani man ie not suffloientiy ( rapid to protect against the flash from an atomic detonation — 9 sw 7 “en. aA SAS i ea RE (7 B