2.2.1 Enewetak Atoll
Of the six shots, BRAVO, ROMEO, and NECTAR caused measurable fallout on
the residence islands of Enewetak Atoll. Generally, such fallout was secondary (onset
was well after the time of detonation) and relatively minor in nature.
was considered a "nuisance factor" (Reference [{2).
UNION and
At the time it
Fallout on Enewetak from Shots
YANKEE was apparently even less significant as evidenced by the
conflicting reports of the minor contamination following these two shots (References
10 and 14).
Fallout from Shot BRAVO began on Enewetak at approximately 1745 hours on
| March, 11 hours after the shot (Reference 10).
Soon after, average gamma
intensities were 3-4 mR/hr and by 2300 hours, when fallout stopped, average
intensities were 10 mR/hr with a maximum intensity of 15 mR/hr being reported.
Figure 2-3 depicts the free-field radiation intensity on the residenceislands (Parry and
Enewetak) of Enewetak Atoll.
Radioactive decay after 2300 hours is inferred from
decay rates measured during the same time period on Bikini Atoll.
Fallout on Enewetak from Shot ROMEO came in two distinct "waves".
It began
at approximately 1700 hours on 27 March and peaked at 2100 hours with average
intensities of 3 mR/hr being reported on Parry Island (Reference 12).
Another period
of fallout began during the late evening of 28 March and did not peak until noon on
30 March, at which time the average island intensities were approximately 9 mR/hr;
maximum intensities were reported to be 15 mR/hr.
intensity for Enewetak Atoll.
Figure 2-4 depicts the radiation
It is seen from the figure that BRAVO fallout
contributed but little to the intensity after Shot ROMEO.
The TG 7.2 unit history for Operation CASTLE (Reference 14) indicates that
Enewetak Island may have received contamination following Shots UNION and
YANKEE.
It states, "The radiation level, however, did not become significant.
Following UNION, a peak intensity of four milliroentgens per hour (mR/hr) was
received, and following YANKEE, the peak reading was only one mR/hr."
Although
these levels are not high, they are contradictory to those given in the JTF-7 rad-safe
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