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THE
ORCBS > Radiation
Safety
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Safety Manual
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 Time,
Distance and Shielding
Three primary means
of eliminating or reducing radiation exposures exist. They are:
Time:
Minimize the time that radioactive materials are handled.
Since the amount of exposure occurs as a function of duration of
exposure, less time means less exposure. This may be achieved by
conducting "dry runs" (practicing the procedures to be
performed, with all of the steps and manipulations performed without
the hazardous materials). Conduct the work quickly and efficiently,
but do not rush.
Distance:
Maximize the distance from the radioactive materials. Dose
is inversely proportional to distance, therefore, greater distance
means less dose. Do not increase the distance to the point wherein
dexterity or control of the materials is jeopardized.
Shielding:
Use shielding wherever it is necessary to reduce or eliminate
exposure. By placing an appropriate shield between the radioactive
source and the worker, radiation is attenuated and exposure may
be completely eliminated or reduced to an acceptable level. The
type and amount of shielding needed to achieve a safe working level
varies with the type and quantity of radioactive material used.
The HVL (half-value layer) may be used as a guide to the thickness
of the shielding necessary to block the radiation. The HVL is the
thickness of the shielding necessary to reduce the radiation dose
rate to half of the original or unshielded dose rate. Refer to the
HVL information in the appendices on specific nuclides.
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Safety Manual Table of Contents
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