bombs detonated over Hiroshima and Nagasaki, Japan were detonated high enough
above the ground to result in the immediate type of radiation exposure of the
people in these cities with little or no fallout occurring.
The effect of
this type of exposure to penetrating radiation is covered in Chapters 8, 9 and 10.
However, when the fireball does touch the surface of the earth large amounts
of incinerated earth, water and dabris are sucked up into the bomb cloud and
adhere to the radioactive fission and induced products.
This mixture of
particles settles to earth, in accordance with Stoke's law, for several
hundred miles in a downwind. direction.
This is designated as the localized
or "close-in" type of fallout and is characterized by radiation of much
higher intensity than occurs with worldwide fallout.
Such a fallout occurred
in the Marshall Islands following the experimental detonation of a thermonuclear
device at Bikini Island on March 1, 1954.
Figure 1 shows a rough map of the
fallout area.
The following table (Table 1) shows the island groups with degree of involvement.
Table 1
Summary of Fallout Exposure
Group*
Composition
Fallout observed
Rongelap
Ailingnae
Rongerik
Utirik
64
18
28
157
Heavy (snowlike)
Moderate (mistlike)
Moderate (mistlike)
None
Marshallese
Marshallese
Americans
Marshallese
Estimated gamma
dose(rads)
175
69
78
14
Extent of
skin lesions
Extensive
Less extensive
S$light
No skin lesions
epilat:
*Also exposed were 23 Japanese fishermen who received a sublethal dose(Miyoshi and
and Kumatori; Koyama; Kumatori et al.).
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