Civil Engineering Reference
In-Depth Information
Fig. 4.1
Possible exposure pathways to man from the nuclear fuel cycle [
3
]
β
γ
- external
- and
-radiation of the gaseous radioactive nuclides in the atmosphere
-submersion) or by immersion in water (swimming),
- radiation from aerosol particles deposited on the ground (soil radiation),
- internal exposure following inhalation of radioactive nuclides (inhalation),
- internal exposure as a result of the intake of contaminated food or water
(ingestion).
(
β
- and
γ
The release rate of radioactive nuclides into the environment depends on the
retention mechanisms incorporated in the engineered safety design of a fuel cycle
facility. Series connection of several containment barriers with low leak rates and
other technical measures allow very high retention factors or low release factors to
be attained.
Gaseous nuclides or aerosols escaping from the plant or discharged in a con-
trolled way through a stack are diluted in the ambient atmosphere. Dilution is a
function of the height of the exhaust stack, the turbulence conditions of the
atmosphere, and the distance from the plant. Radionuclides are also deposited on
the ground by dry and wet disposal. Aqueous radioactive discharges are diluted as a
