‘WRakie DELAYED SHUTTER STUDI®S$ In the delayed shutter exposures, retinal burns, 6 of 16 rabbits sustained The lesions were produced mostly in cases where the exposure included the maximum or near maximum flux of the second pulse. Increments of the flash beyond 0.6 seconds did not produce burns in this event. FILTER STUDTES © Burns produced behind filters at URIAH and VAN at 3.0 and 3.8 miles, respectively, were similar in size and appearance to blink reflex lesions sustained on JAPTAN (DAVID) at 8.1 miles distance from ground zero, From this it is inferred that the filters reduced the caloric dose and dose rate at URIAH and VAN to a level below that veto could produce burns, PROTECTIVE ELECTRONIC SHUTTERS These shutters were inoperative at H hour due to a fire in the wiring circuit at H -4 minutes, With the grid mechanism fully open, the shutter still reduces the incident visible light by about 60 percent. As a first approximation it is estimated that the energy reaghing the rabbit eye was effectively reduced a It is of interest that no lesions were produced in the animals behind the protective shutters, Within the limits imposed by the yield threshold of burn production for this event lies between Gea CONCLUSTONS The blink reflex time for animals and man is not sufficiently a rapid to protect against the flash from an atomic detonation | on koeSD/D98, ge Het se -~ 17 - Q

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