Task
Analysis of exposures, %
Group
Oto2r
2to4r
4to6r
G6tol2r
Over12r
Total
exposed
7.1
1.2
7.3 7.4
7.5
Hq. JTF-7
68
94.8
80.3
83.2
13.2
100
21.7
3.9
14.5
8.8
12.3
0
8.4
1.3
3.4
4.6
13.1
0
2.1
0
1.7
2.1
1.0
0
0.3
0
0.1
1.7
0.1
0
1,300
551
6,153
759
1,421
90
Total 10,174
order to provide the Task Force Rad-Safe Officer with the necessary information to accurately evaluate any radiological hazard. In particular, samples analyzed by the Section included the following:
a. Lagoon samples to prevent undue radiological contamination to surface vessels an-
chored within the lagoon.
b. Drinking-water samples from the evaporators of ships anchored in contaminated
have been exposed as a result of working with{tritium gas] ia
g.- Other special samples as required by TG-7.1.
. Organization and equipment: The Section included an officer supervisor and four navy
hospital technicians who had been given a brief training period at LASL prior to joining
TU-7. This organization proved to be adequate to handle any of the assignments,
A mobile radiological field laboratory, completely equipped for carrying out chemical as well as radiological analysis of samples, was stationed on board the USS Bairoko
and was utilized throughout the operation for carrying out most of the laboratory work.
An alpha scintillation counter, two counting rate meters, and four Geiger-Mueller type
detectors and Berkeley scaler combinations comprised the major components of the
laboratory. An adequate supply of spare parts enabled the instrument repair section of
the Laboratory Group to keep the instruments in good working order,
Work load: The majority of the samples analyzed by the Section were water samples
consisting of samples taken from the lagoon and drinking-water samples from the ships
anchored in contaminated water. Fig. 5.1 shows graphically the number of such samples analyzed by weekly periods from 1 March to 10 May 1954. Peak periods occurred
the week following /ARAUd cand Roniggevents. In addition to these samples, air samples,
soil samples, decay rates, etc., were run. A total of 706 samples were analyzed during
Operation Castle from the period 1 March to 14 May 1954.
. Occurrence of fall-out on USS Bairoko: The operation of the Section was rendered more
difficult, particularly following/4CQv¢, by the occurrenceof fall-out on the USS Bairoko.
On this occasion the background becamesohigh that precise counting became impos-_
sible. Primary fall-out commenced.at 0755, 1 March, 1 hr and 24 min after[ BOQ -
and continued off and on throughout the day. Fall-out again occurred at 2230 on 28
March, 41 hr following RAE) This was a secondary fall-out, however, as was that
45
cam
lagoon water.
c. Drinking-water and food samples as dictated by the occurrence of fall-out on inhabited islands.
,
d. Air samples collected in fall-out areas by vacuum typeair filters and cascadeimpactor slides.
e. Solid soil samples containing fall-out particulate matter for the determination of the
decay rate and apparent energies of the various types of radiations.
{. Urine samples analyzed for tritium content were obtained from personnel who may