PISONIA_ EVENT
OPERATION HARDTA
1.
Eniwetok
The PISCNIA device was detonated on a barge off Yvonne Island,
Atoll, at 1100M, 18 July 1958
The yield was approximately
wn: the cloud rose to
2,
The P2V aircraft (Wildroot #10) was vectored on a line from
Keith to Bruce and then gradually across the upper portion of the lagoon
on radials from Alvin,
Heavy rain showers caused isolated readings of
5 r/or, 6 r/hr, and 7 r/hr throuzhout the area adjacent to ground zero.
Readings attenuated quickly, but it was difficult to obtain a picture of
the situation for several hours.
The P2V was placed on a barrier patrol
on radials of 240 degrees and 250 degrees for 75 miles from Eniwetok.
A
final clearing run was made to Ujelang, and the P2V was released at 1845M.
3.
Weather prevented utilization of helicopter survay aircraft.
Meboats were dis-atched at 1415M.
One turned back at Yvonne because of
hot water, and the other read 1 r/br at the Mack photo tower.
at 1800M,.
Two
Both returned
A helicopter survey was made the following morning, from 0700M
degrees for approximately 250 miles.
Local radiation level on Eimer rose
to a peak of 30 mr/hr suddenly, at 1448M, in heavy rain.
TAB A
Intensity quickly
—
It is estimated that tha fallout fell along a bearing of 270
a9
4.
re
anv 4
=
to O900M, and readings of 1 mr/hr ware made on Yvonne and Wilma.