FF3/7.3/32:mf
J15-9
of their washdown systems, concentrations of up to seve
roentgens per hour
built up on BATROKO and PHILIP (plane guard for BAIROKO), with average readings’
~gaching 500 and 750 nillircentgens per hour, respectively,
The fallout pattern
was not symmetrical, since both OSTES and CUNTISS, appreaximately the aane distance
“von ground zgere as BALIOKO but on opposite sides. of her, reccived less contam-.
ination, Other ships, including these which had been moved southward before the
detonation, received none of this early fallout.
3. In addition to the early heavy fallout encountered by some ships during the
moming, in the afternoon and: early evening of 1 March, light, invisible fallout
was detected by all ships in the area, Again, damage control measures were em-
ployed by all ships, This fallout commenced about 1300M, reached a maximum about
1800M and decreased to almost zero by 2400M, Average readings during this period
reached 300 mr per hour, with maximm concentration up to 475 mr per hour, Ships
experiencing this fallout were located in the general area between true bearings
Llo*T to 155°T from ground zero, distances from 20 to 70 miles. .
he Decontamination of the ships by the ships ow decontamination crews, Pine
ie
natural radioactive decay, brought the radioactive intensity down rapidly.
following table shows average topside intensities in milliroentgens in wie
roentgens per hour (gamma only) of three representative ships at various timep:
DATE
TIME
BAIROKO
PHILIP
GYPsY
1 MAR
0900
1000
1100
500
500
500
750
265
196
-=---seo,
1200
350
5
1400
240
_ 138
2000
180
199
150
2 MAR
0000
01,00
0800
1200
1600
2000
160
145
134,
108
36
30
188
156
I,
78
60
La
130
110
so
L5
10
35
3 MAR
0000
04,00
0800
39
41
34
35
35
25
1300
1500
1600
1700
1800
1900
300
200
170
140
200
180
~—(t
U7
134
180
225
262
194
---
-
---
7
30
200
230°
250
200