FF3/7.3/32:mf
ee
of their washdown systems, concentrations of up to several
roentgens per hour
built up on BATROKO and: PHILIP (plane guard for BAIROKO), with average readings’
sgaching 500 and 750 nillircentgens per hour, respectively, The fallout pattern
:
vas not symmetrical, since both DSTES and CURTISS, approximately the sane distance
“von ground zero as BAINOKO but on opposite aides.of her, received less contam-.
‘
ination.
Other ships, including these which had been moved southwardbefore the
detonation, received none of this early fallout.
3.
In addition to the early heavy fallout encountered by some chips during the
moming, in the afternoon andearly evening of 1 March, light, invisible fallout
was detected by all ships in the area, Again, damage control measures wore em~
ployed: byall ships, This fallout commenced about 1300M, reached a naximm about:
1800M and decreased to almost zero by 2400M,
Average readings during thie period. -
reached 300 mr per hour, with maximum concentration up to 475 mr per hour.. Ships
experiencing this fallout were located in the general area between trus bearings
oerTt to 155°T from ground zero, distances from
n20 to 70 miles... ~
oo
4. Decontamination of the ships by the ships ow decontamination crews, plus
natural radioactive decay, brought the radioactive intensity down rapidly. The
following table shows average topside ‘intensities in milliroentgens in milli-
roentgens per hour (gamma only) of three representative ships at various timeg: DATE
TIME
1 MAR
0900
1000
1100
2200
1300
1400.
1500
1600
1700
1800
GYPSY -
750
265
19%
|
U5
U7:
_ 138
134
* 180
225
262 —
0000
1,00
0800
160
U5
134,
188
156
ni,
1600
2000
36
30
60
4h?
1200
3 MAR
PHILIP
500
500
500
350
300
240
200
170
140
200
1900
2000
2 MAR
BATROKO
0000
04,00
0800
.
180
180
108
27
25
22
.
-
194
199
.
~
m-= =
’
-<--.
22.
-2;
Bo
mee
7.
Dos,
30..
re
“200
- 230°
250:
20
150
130
110
80
78
45
er
39
Al
3h
40
>)
35
35
25
-
Ve
aOEa ee LD