however, if a key experiment vital to the success of the shot will _ not be successful for any reason. Built-in safeguards automatically can stop a detonation if certain key experiments are not functioning at any second up to detonation, This occurred on a spring 1952 shot. . a \ . Any zshange in the forecast wind direction or velocity could result in a postponement. The formulae for predicting the intensity and location of significant fallout, on-site and off-site, must be matched to the varying weather forecasts throughout the night. The 1 conservative guide to public radiation exposure -- 3.9 roentgens per series -- is determining in evaluating off-site fallout forecasts. If there are any indications that fallout from the present shot will cause exposure-approaching that figure at any inhabited nearby point or if new fallout plus fallout from a previous shot in the series would bring the total near that figure, the shot will be postponed. It may be seen-that as a series progresses, the segment of acceptable wind direction for a sensitive shot may grow constantly more restricted. Related both to technical and safety considerations are the fac-— tors of cloud cover and atmospheric moisture. Clouds can prevent air operations, including key experiments. Any indication of significant precipitation over the test site or nearby region could result in a postponement. Precipitation at more than 200-300 miles is not a major factor, because by then radioactivity in the cloud has greatly decreased, For an air drop, any malfunctioning of the drop aircraft would of course cause a postponement. With heavy conzentrations cf aircraft above NTS, provision has necessariiy been made for postponement if any craft is dangerously cut of place for any reason. Ail fiights are monitored by radars stationed within a few feet of the master control room at the Controi Point. Oniy the reaction time of individuals invoived determines the time required ty stop a test in-such a case. Forecasts of the intensity and location of blast waves, based on weather forecasts, are made with each weather forecast. High explosive detonations fired shortly before the nuclear shot send out waves which are recorded on microbarographic equipment in nearby communities. A postponement couid result if there was a firm forecast that high blast levels would be recorded in communities. ae All individuals must be checked as having cleared the forward area. If a singie person were unaccounted for, the shot probably would be delayed. Pre~chot consideration is given to the flash effect from the viewpoint cf issuing the necessary public warnings and taking such - 18 ~ The flash CO ert TOE LR 4 a4 sy steps as asking state officials to establish roadblocks. effect weuld now cause a postponement.