It should be noted that particles collected in close-in early
fallout from a nuclear detonation, such as those during atmospheric
nuclear testing, contain multiple radionuclides including small amounts
of plutonium.
Fallout particles from near surface detonations tend to
be of larger size (10 to > 100 microns) than particles from airbursts
(1 to 3 microns).
Most of the tests at Bikini were at or near surface
bursts.
Fallout particles from different portions of the cloud from a
surface detonation contain different ratios of radionuclides due to
fractionation.
For example, samples collected from a dust column
within a few minutes after detonation are depleted with respect to
volatile isotopes as well. as isotopes having volatile or gaseous
precursors.
Samples collected from clouds at 70 to 80 kilometers
from the detonation are enriched by isotopes having gaseous precursors.
Dose to Lung Received From Pu-239 Contaminated Areas.
It is difficult
but not impossible to predict lung doses resulting from continuous
occupancy of plutonium contaminated areas.
Plutonium at Bikini is
most likely to be in the oxide form and relatively insoluble.
If
values for resuspension (including reduction with time), air attentuation
and particle size obtained from field tests are used along with para-
sae
MMB (PO