Adreraft The contamination level on the YAG-39 aircraft WES SO low that a decontamination study was not warranted and the ef- fectiveness of the washdown system could not be evaluated ac~ curately. The YAG-40 aircraft was sufficiently contaminated to warrant an experimental decontamination study. began on R+5 and ended on R+9 days. This study A series of decontami- nation processes were employed which,with the aid of one rain squall and decay, reduced the gamma radiation level at the cockpit from 850 mr/hr to 45 mr/hr. At the same time, the gamma intensity level on an area on a wing section was reduced from 10 r/hr to 85 mr/hr. The left magneto on the YAG-39 air-~ craft would not cheek out when the aircraft was turned up after the test, but no material damage was detected on the YAG-40 aircraft. Interior Contamination_ Air samplers and particle collectors operated normally over the designed time interval after debarking, shutting off at H+t44 hours. Maximum field intensity indicated by gamma detectors on the YAG-+0 occurred at about H+8 hours. However, precut sections of ventilation duct continued to be exposed to activity deposition until H+1% hours. Neither air samplers nor duct sections showed appreciable activity. Two topside nillipore filters showed moderately high ectivity but here the existence of surface streaks leads to suspicion of direct fallout contamination rather than collection of airborne particulate mg nent —_— —--—- &xd gg Ul

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