14
The level was 1/3 this
amount if the consumption period was assumed
to last for 30 days.
This guidance was accepted as doctrine by U.S. Civil Defense
organizations over the next several years.
The count-rate produced by
a few cc's of sample containing 9 x 1072 microcuries per cc is easily
measured by an ordinary Geiger counter instrument.
The Geiger tube
probe with the beta shield open was placed over a compound in the lid
of a standard 4-ounce ointment tin containing an amount of U-238 or
radium that empirically had been adjusted to give the count rate desired.
The unknown water or food sample was placed in the bottom section of
the tin, and a comparison of the two readings indicated whether the
radioactivity of the sample was above or below the acceptable level.
These comparison standards were purchased by OCD and distributed so
as to be available for emergency use.
Today both the standards and the measurement techniques are no
longer used by U.S. Civil Defense for the following reasons.
First,
the fallout is now known to be a principal hazard of a nuclear war.
Studies of hypothetical nuclear attacks show that fallout could seriously
affect very large areas of the country.
Thus, adherence to the con-
servatism reflected in the earlier calculations could unnecessarily deny
the use of badly-needed food and water.
Second, because of high back-
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