PART B: COMPUTE NUCLEAR DATA IN AREAS OF INDUCED RADIATION
Neutrons are produced in all nuclear weapon detonations. Some of these neutrons may be captured by
the various elements in the soil under the burst. As a result of neutron capture, some of these elements
become radioactive, generally emitting beta particles and gamma radiation for an extended period of
time following an explosion. Beta particles are a negligible hazard unless the radioactive material
makes direct contact with the skin for an extended period of time. In this case, the beta particles can
cause skin irritations varying from reddening to open sores. In contrast gamma radiation readily
penetrates the body and can cause radiation injury and even death. Consequently, the external military
hazard of induced radiation is determined substantially through an analysis of the dose rate of the
emitted gamma radiation. The principal characteristics of induced radiation are:
1.
Localized Symmetrical Pattern.
The pattern of induced radiation is circular around ground zero. The dose rates within the pattern are
highest at ground zero and decrease with distance from ground zero. The pattern is much smaller than
the fallout pattern would be if the same weapon were burst on the surface. Weather conditions have no
influence on the location and size of the pattern or the dose rate of induced radiation, and there is no
shifting of the pattern by surface winds. The pattern, if produced, will always be located around ground
zero.
2.
Difficult to Decontaminate.
Since the soil in the target area is made radioactive to a depth of about .5 meter, decontamination is
difficult, requiring the removal of the top 10 centimeters of soil where most of the radiation exists. In
contrast, fallout is a deposit of radioactive dust on the surface and can be removed with somewhat more
ease than induced radiation. Both types can be covered by earth.
3.
The decay characteristics of induced radiation are considerably different from those of fallout. Fallout is
a mixture of many different substances, all with different rates of decay. Induced radiation is produced
primarily in aluminum, manganese, and sodium. Other elements either emit so little gammna radiation
or decay so fast that they are less important. During the first 1/2 hour after a burst, the main contributor
to induced radiation is radioactive aluminum. Aluminum is one of the most abundant elements most all
soils contain. Radioactive aluminum has a
CM2308
6-26
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