-

viCLASSIFIED
“ila

f

to date as reports came in and an iso-intensity line of 0.1 r per day

in the lagoon water was also plotted on this chart,

The surface and air radexes were plotted daily from weather data

obtained from Aerology. Utilising a vector analysis of the wind
velocities, fall-out patterns for the surface, 15,000, 20,000, 25,000
and 30,000 feet were determined.

These patterns were plotted on charts

with a superimposed polar grid. From the fall-out patterns, the surface
radex, given as two bearings from zero point, and also recommendations
as to the direction of the third pass for each drone plane mother were
determined.

Definite criteria were used to determine whether or not the day

was operational from a radiological safety viewpoint. If the fall-out
from 45,000 feet or below, did not extend between 90°T or 170°T from
zero point, the day was considered operational, If the fall-out from

45,000 feet fell on the bearing of Eniwetok-Parry islands (150°-160°)

the day was considered questionable with moderate hazard. If the faliout from 35,000 feet or below fell on these islands, the day was considered non-operationalL,
Three days preceding the test a forecast for a test day was made,
and on the day before the test day the latest weather forecast was
presented at 1800. Actual wind data was plotted at intervals from this
time to 0300 at which time the last baloon sounding was made and the
data was prepared for the briefing.
X-RAY Plus Two - YOKE Test

Considerable radioactivity was found on the islands west of the

test. island, indicating extensive fall-out.

Evidences of fall-out

elsewhere were slight, A consolidated report was prepared and all the
evidences of fall-out noted during the days following the test.
On X-RAY-plus 5, Commander Task Group 7.6 sent a report to Camander

Joint Task Force 7 stating that the survey of all the perimeter islands

had been completed, and reconrmended that long term closure of the islands
from Yeiri westward to the southwest passage inclusive be instituted
because of the radioactivity discovered along the beaches and the evidences
ef fall-out. The temporary clearance of the other islands and of the
layjoon beaches on these islands for swimming was recommended,
Dust collectors had been set up on each of the principal ships of
the Task Force, and were e> -:ined daily, together with a careful check
of the evaporators.
Several surveys were ade on the test island and the csradual retreat of the iso-ihtensity lines was plotted in Radop.

eam

\

Select target paragraph3