e. A single radiation measurement usually has a limited operational significance (except to the
unit in the immediate area), since it gives information at the point of the reading only. A number of
individual measurements considered together can give a picture of the radiation pattern over an entire
area.
f. RADIAC instruments measure GAMMA radiation without regard to its source. The doses or
dose rates of radiation measured may represent radiation from fallout, neutron-induced GAMMA
activity, or a combination of these. These radioactive materials emit ALPHA, BETA, and GAMMA
radiation. However, only GAMMA is a militarily significant hazard, if the proper protective measures
are taken by exposed personnel.
g. Ground (outside) dose rates are the basic reference used to determine the magnitude of a
contamination hazard. The ground dose rate is the unshielded dose rate measured 1 meter above ground
level (about waist high). This dose rate approximates the average whole body dose rate a person would
receive if standing in the open in the contaminated area at the location of the measurement.
2.
RADIAC Instruments.
RADIAC instruments are required for the detection of nuclear radiation. Radiological contamination
cannot be detected by the physical senses. Radiation absorbed by the body is cumulative in nature and
commanders must be on the alert that individuals do not accumulate casualty-producing amounts.
a. IM-93/UD Series Dosimeter.
Dosimeters are devices designed to measure the total radiation (GAMMA) dose received by an
individual. The standard tactical dosimeter is the IM-93/UD Series. Normally, they are issued on the
basis of two per platoon-size unit, with two spares in the company headquarters. IM-93/UD Dosimeters
are direct-reading pocket dosimeters. These dosimeters have a range of 0 to 600 cGy and an accuracy
rate of 10%. The scale gradation is in 20 cGy increments. The maximum permissible leakage is 12
cGy in a 24-hour period.
b. IM-147/PD Dosimeter.
This dosimeter has a range of 0 to 50 cGy and an accuracy rate of ƒ 10%. The IM-147/PD Dosimeter is
an intermediate range instrument issued to survey parties and others whose dose is not expected to
exceed 50 cGy. The maximum permissible leakage is 1 cGy in a 24-hour period. Maximum
permissible leakage rate is based on 2% of the scale.
2-9
CM 2506
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