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EXCERPTS FROM LETTER FROM PAUL C. PINE TO DAFOL FROMEN, DATED JULY 1, 1954.
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(Signature of person mak
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New York Onerations Office
"herial Monitoring of Fell-Out in See Wester (Operstion CASTLE)
An initiel ettempt to locate and evaluate fall-out activity was made
by plecing a series of 300 rafts in the sector centered about the
predicted path of the radioactive cloud resulting from the YANLEE shot.
"These rafts were placed in clusters of 10 on headings normal to the
prediction, with five clusters per heading; the first line started
at 30 miles from ground zero at Bikini Atoll. Six lines of rafts
were laid in this manner, so that the refts eppeared at approximately
18° intervels throughout the sector, up to a distance of 180 miles.
"The individual refts were composed of either polystyrene foam, 4 inches
thick x 4 feet x 5 feet, or of 4-foot x 6-foot plywood units consist-
ing of two sheets of. plywood seperated by two infleted tire inner-tubes,
so that the upper sheet floated approximately 3 inches above the water.
The rafts were impregnated with a low viscosity silicon oil, and
approximetely 50% of the units were dyejd red and numerically identified.
On D +1, two search planes were sent out in an effort to locate the
rafts; on thet day approximately seven were found. These were mainly
in the first two lines of clusters. On D + 3, approximately 20 rafts
were located, of which only one had identification remaining. These
rafts were also in the first two lines of rafts leid, and the reidentified raft was one of the group originelly identified on D « l.
The position of the refts had changed, due to the tidal drift, but the
clusters were fairly compact. The location problem was serious, and,
on this basis, further raft-droprping activity would seem to be inadvis~able.
"In compliance with a request from the Scriprs Oceeanorraphic Institute
Consultant, a heading was flown in the predicted fall-out using aerial
survey techniques. It wes possible to identify a path of activity,
which by altitude change was identified with the sea water. The response
on the detector indiceted elmost square wave cherecteristics with a
width of activity measuring 9 miles. Drta were then taken at 50 miles
from ground zero and et 75 miles, with similar sherp areas of activity
indicated. With but these three points, it wes evident that the predicted wind trajectory could be identified with the redioective fallout and that e change of wind direction shortly efter shot time might
have existed since the data indiceted a bow in the region of 25 miles.
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