User Guide

strongly absorbed by the air it travels through, which causes the

intensity to drop off much more rapidly.

These scaling laws show that the effects of thermal radiation

grow rapidly with yield (relative to blast), while those of radiation

rapidly decline.

In a small nuclear attack (bomb yield approx. 15kT) casualties

(including fatalities) would be seen from all three causes. Burns

(including those caused by an ensuing fire storm) would be the most

prevalent serious injury (two thirds of those who would die the first

day would be burn victims), and occur at the greatest range. Blast

and burn injuries would be found in 60-70% of all survivors. People

close enough to suffer significant radiation illness would be well

inside the lethal effects radius for blast and flash burns, as a result

only 30% of injured survivors would show radiation illness. Many of

those people would be sheltered from burns and blast and thus

escape the main effects. Even so, most victims with radiation illness

would also have blast injuries or burns as well.

With yields in the range of hundreds of kilotons or greater (typ-

ical for strategic warheads) immediate radiation injury becomes

insignificant. Dangerous radiation levels only exist so close to the

explosion that surviving the blast is impossible. On the other hand,

fatal burns can be inflicted well beyond the range of substantial blast

damage. A 20 megaton bomb can cause potentially fatal third degree

burns at a range of 40km, where the blast can do little more than

break windows and cause superficial cuts.

A convenient rule of thumb for estimating the short-term fatali-

ties from all causes due to a nuclear attack is to count everyone inside

the 5 psi blast overpressure contour around the hypocenter as a fatal-

ity. In reality, substantial numbers of people inside the contour will

survive and substantial numbers outside the contour will die, but the

assumption is that these two groups will be roughly equal in size and

balance out. This completely ignores any possible fallout effects.

OVERVIEW OF DELAYED EFFECTS

Radioactive Contamination. The chief delayed effect is

the creation of huge amounts of radioactive material with long

lifetimes (half-lifes ranging from days to millennia). The primary

source of these products is the debris left from fission reactions. A

potentially significant secondary source is neutron capture by

non-radioactive isotopes both within the bomb and in the outside

environment.

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