toe i
PowaN BABLATION INJURY
wrepertion ef contaminant frum eau onrfo-c-.
That re-ssining is firmly fized aad is net litely
te becen e eirbernecnsily. If 2 personnel decontamination center is established, it should be
relativety mobile and isolated from more permanent buildings where definitive care is given.
This stems from the fact that contamination
can only be transferred, not destroyed, and the
decontamination area is likely to become quite
“hot” in a relatively short time. Tinned goods
can be eaten with complete safety and it is
highly unlikely that city water systems outside
the area of blast damage will be contaminuted
soon after a burst. One thing appears to be
certain—any effects from internal radiation will
be long range and «::] be of no concern in the
acute period. Total body radiation from
gamma rays, and skin irradiation from beta
emitters will be the chief radiological concern
at early times following an explosion.
6.36
Evasive Action; Prosection From Fallout
Some warning of possible fallout will be
available and the falling radio-active material
may actually be visible. As stated, the pattern
of fallout will depend on wind velocities and
other weather conditions, and the pattern is thus
difficult to predict under the best of circumstances. However, it will be apparent that in
closer-in areas, fallout may not occur for severn] minutes after the blast and this period may
extend to several hours at greater distances and
with slower wind velocities. Thus, there is some
time for evasive action.
Consideration might
be given to evacuating the area if possible fallaut patterns have been investigated and are believed to be predictable. Or it may he possible
to take shelter. Sufficient time probably would
be available to allowrelatively complete preparation for an extended stay in adequate shelters
with storing of sufficient food and water to
allow some axdvantaye to be taken of the decay
of fission product radiation with safer evacuation of an ares a few dave after the fallout.
Facilities may, for the moat part, be enmentially
intact, such as water, power, fire hghting equip
ment, etc. Tn this sense. at lewst, one is im:
&
naeouieny Seleer of than with the area of
blast and thermal damage.
With regard to efectivences of shelters in the
fallow area, the following estimates have besa
released. A frame house would reduce the total
dose received by one-half, and a brick or concrete structure would be more effective. A
basement would reduce the total exposure to
one-tenth of ita value. Ina shelter of thickness
equivalent to three feet of earth, the dose would
be reduced to one five-thoussndth of its value,
affording complete protection in the most hesv-
ily contaminated areas.
It shoukd also be noted, on the other hand,
that while the decay of fission product radia-
tions is extremely rapid over the first few minutes after detonation, the rate of decay becomes
considerably lew rapid in the succeeding hours
(2). Thus, with fallout occurring some hours
after the blast, if adequate shelter is not available, earlier evacuation may be better than re-
lying on partial shelter and on rapid decay of
the radiation field.
Starting at 1 hour after
the blast, » given dose rate will fall to about
44 percent of its value by | hour later. However, at 10 hours after the blast, a given dose
rate will fall by only 11 percent of its value in
a period of | hour, e. g., the dose rate at {1 hours
will be 49 percent of what it was at 10 hours.
Such statements as “more than S0 percent of
the radiation dose from atomic debris will be
delivered within 10 hours of the explosion time”
are true only if fallout occurs immediately after
the detonation, If the maximum fallout and
Thus maximum exposure rates ina fallout area
have not occurred for several hours, the rate
of fallout in the area obviously will not be as
rapid as it would be for earlier fallout material.
6.4
Estimation of the Severity of Exposure to GammaRadiation
6.41
Predictions From Physical Estimeees of Dose
If the aleolute nsitivity of man to radiahon were known, and if it were feasible to determine the deee t yroups under catasd rophe