9.4 OPL RATIONS
9.4.1 Survey Vessel.
Three ships were utilized in making the Project 2.62 fallout survey
afterShot. these were destroyer escorts, the USS McGinty (DE 365) and the USS
silverstein (DE 534). These two ships were outfitted with the following equipment: (1) detector
probes for measuring the dose rate at the water surface, plus the allied equipment necessary
for measuring the dose rate at depths to and belowthe thermocline; (2) mast-head instruments
(Nayv-rad), for scanning the sea Surface for radiation from atop the bridge; (3) drogues with
which to mark water masses of particular interest for measurement of subsequent current drift;
and (4) water-sampling equipment for the taking of surface samples.
The third ship was the research vessel M/V Horizon of SIO. The ship was outfitted similarly
to the two destroyer escorts and had the following additional equipment: (1) decay tank for measuring the decay of radioactivity as recorded by the thick-walled probe; (2) radiochemical laboratory for a systematic study of the extent of radioactive contamination of the marine environment,
(3) water-sampling equipment for the collection of samples from any desired depth; and (4) ocean-
ographic equipment for making allied measurements and for collecting marine organisms and
bottom samples.
In addition to these three vessels, the two Project 2.63 YAG’s were used in the overall fallout
survey. For joint Project 2.62 and 2.63 purposes, these two ships were outfitted with probes
and allied equipment necessary to measure radioactivity at the water surface and at depths.
2.4.2 Control Center.
In order to coordinate the movements of the survey vessels, a con-
trol center was set up on the USS Estes (AGC-12) under the direction of the Program 2 staff.
This control center was operated during the entire time that each survey was in progress.
Representatives from the participating projects were present during this time and had at their
disposal the radio equipment necessary to communicate, advise, and direct all survey units.
It was the function of these representatives and of the Program 2 staff to: (1) coordinate the
movements of the survey units so that any discrepancies in measured values could be resolved
immediately; (2) ensure that all the areas of the fallout pattern were surveyed in sufficient detail to yield a complete picture; and (3) direct the various survey units to rendezvous points for
intercalibration checks.
2.4.3 Procedures. During the hours of darkness preceding and at the detonation time of each
event, Ships remained at sea on stations assigned by CTG 7.3. After the shot, the survey ships
remained on station and in communication with the control center. During this period of waiting
after the shot, the control center sent estimated positions of the boundaries and axis of the expected fallout pattern. These messages, as well as all others pertaining to the survey, were
Sent by radio in a code agreed upon by the participating projects.
Based upon information being received from the YAG’s and other projects, the control center
determined when it was radiologically safe for the Project 2.62 ships to commence their survey.
The three ships were informed of this decision and were also sent a recommended course for
Starting the survey.
From this time on, to the end of the survey, the procedure for the destroyer escorts was as
follows: (1) the ship proceeded on recommended course until the boundary of fallout radiation
Was contacted; (2) she passed through this boundary into the area of contaminated water and
made a station consisting of a bathythermograph (BT) measurementto determine the thermoCline depth, measurements to determine the depth to which the radioactivity had penetrated,
Collection of surface-water sample for subsequent analysis by Project 2.62 and other projects,
and launching of a drogue! to mark this region of contaminated water; (3) the ship then proceeded
back through the boundary into clean water on a course approximately 45 degrees to the edge of
———
lam.
This method of tagging water was not used extensively after Shot Cherokee, because the drogues
drifted into the area of deep~moored skiffs and were suspected of parting the pennant connecting the
Skiff with deep float.
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