southeast of GZ) at 06/1600M; 0.005 r/hr at Mejit Island (350 nautical miles east-southeast of
GZ) at 07/1300M; 0.003 r/hr at Ormed Island, Wotje Atoll (320 nautical miles southeast of GZ)
at 05/1600M; 0.001 r/hr at Erikub Island, Erikub Atoll (320 nautical miles southeast of GZ) at
05/1715M; 0.002 r/hr at Kaven Island, Maloelap Atoll (365 nautical miles southeast of GZ) at
06/1130M; 0.001 r/hr at Wotho Island, Wotho Atoll (100 nautical miles south-southeast of GZ)
at 06/1615M; 0.0004 r/hr at Uliga Island, Majuro Atoll (440 nautical miles southeast of GZ) at
07/1200M; and 0.160 r/hr at Bikar Island, Bikar Atoll (290 nautical miles east-northeast of
GZ) at 09/1200M.
4.3.2 §
Rorigo
Results of the initial amec,radiological-safety survey indicated no extensive recontamination except within the Bokobyaadaa—Namu chain. Slight recontamination occurred within the
remainder of the Atoll. Intensities of 1000 to 2000 r/hr could have been encountered in the
crater area (Fig. 4.2).
A secondary fall-out occurred the night of AvGco +1 day in the southern islands of the Atoll
and aboard the ships anchored off Eninman. This fall-out is shown in Figs. 4.3, 4.4, and 4.8 in
the late radiation peaks of the
interval. Intensities leveled off between 0700 and 0800 on
KCMEC +2 days with residual topside levels on the Ainsworth at 8 mr/hr, the Estes at 12 mr/hr,
and the Bairoko at 30 mr/hr, whereas intensities on the adjacent islands were increased by
100 mr/nr.
The western quarter of the lagoon was recontaminated by radioactive sediment with radiation levels comparatle to those of ARAUL , The flushing of lagoon waters through the southwest
passages materially increased background radiationlevels in the vicinity of Ourukaen, Bokoaetokutoku, and Bokororyuru.
The USS Epperson,at a position 18 miles north-northwest of Enyu anchorage, reported a
fall-out of 100 mr/hr at 27/2030M March 1954,
Eniwetok Atoll experienced a light fall-out of radioactive material or!Motto} 1 day. This
fall-out peaked at about 9 mr/hr at approximately 30/1200M (Fig. 4.9). No significant fall-out
was reported from areas outside the Pacific Proving Grounds.
4.3.3
~~.
Koo
The initial radiological-safety survey was able to determine that Bokobyaadaa, Namu,
Eniirikku, and Bikini islands and the Yurochi-Aomoen chain of islands were materially con-
taminated by the, hoon
detonation (Fig. 4.10), The lagoon survey indicated contaminated
waters spreading north from the crater. Consequently all the lagoon northwest of a line between Airukiiji and Bikini was considered contaminated to an extent that would require radiological-safety control within the first few days.
Koon
“Jerater was materially different in size and surrounding intensities from that
ofBRAVE fand|ome With the exception of size and water in the crater, there was much similarity to the crater of the Jangle surface burst. Small sand dunes surrounding the crater were
extremely radiqactive. These dunes were later washed away by wave action from)Yvon’
.
er
:
andthe revised{
Rain squalls shortly after detonation were instrumental in the removal of contamination
from equipment and islands. No significant fall-out was reported by land areas outside the
Pacific Proving Grounds.
4.3.4 |
_
~
Ghior
The initial survey of the Atoll indicated that recontamination was limited to the Yurochi-—
Aomoen and the Bikini— Enyu sequence of islands (Fig. 4.11). Waters of the north central portion of the lagoon were materially contaminated in a rough circular pattern about 3 miles in
diameter. Readings of 4.2 r/hr were obtained at an altitude of approximately 500 ft above GZ.
This contamination settled with time, and thercfore a layer of maximum contamination could
be found at a 60-ft depth 30 hr after detonation. Surface contamination moved to the west and
southwest, flushing over the western reef and through the southwest passages,
26