THE PRECAUTIONARY MEASURES TAKEN
FOR THE TESTS IN FRENCH POLYNESIA
Among the numerous precautions taken before conducting a nuclear test, studies are obviously made of local weather conditions, particularly of the prevailing and occasional winds at
different altitudes. With this information the testers can predict the radioactive cloud movement
and determine the perimeter of the local fallout, outside of which no radiation above the threshold
of tolerance can be produced.
Several studies had previously been made on the wind system in Polynesia, but it was still
necessary to substantiate their findings. and clarify certain special points on which the data was in-
adequate. The information necded was collected over a three-year period by a network of about
15 meteorological wind and temperature observation stations.
These stations’ observations, combined with those of French military ships and aircraft.
made it possible to gain actual experience with the weather conditions prevailing in the Southeast
Pacific. It has been established that there is a stable west wind at a high altitude, and that any disturbances can be predicted for a great part of the year.
_ By knowing the meteorological factors, it is possible to define the zoneof fallout and,taking
into account the yield and altitude of the firing, to assess the amount of contamination with sufficient accuracy.
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