Civil Engineering Reference
In-Depth Information
Chapter 4
Radioactive Releases from Nuclear Power
Plants During Normal Operation
Abstract
This chapter lists the different main radioactive isotopes produced in the
fuel of nuclear plants which are released in very small amounts into the environ-
ment. It then explains the different pathways leading to radioactive exposure of the
human body. Several containment barriers in a nuclear power plant lead to
extremely low leak rates of radioactive substances. This is followed by the defini-
tion of the radiation dose, the radiation weighting factors, the tissue weighting
factors, the equivalent radiation dose and the natural background radiation dose.
Radiation exposure from man-made sources is strictly controlled by governmental
agencies. Permissible radiation dose limits were set by governments for radioactive
releases from nuclear installations for the population and for employees who might
receive enhanced radiation during their occupation. This also holds for rescue
operation teams after a severe nuclear accident. Finally the radioactive effluents
of LWRs and the effective doses to the public for airborne and liquid effluents of
LWRs are presented. This is compared with the release of radioactive nuclides from
coal fired plants.
4.1 Radioactive Releases and Exposure Pathways
During normal operation of nuclear power plants and other facilities of the nuclear
fuel cycle, small amounts of radioactivity are released into the environment at a
monitored and controlled rate. Airborne radioactivity includes the radioisotopes of
the noble gases krypton, xenon, radon, of tritium, C-14, and also of fission products
and fuel aerosols. Liquid effluents released into rivers, large lakes or the ocean
contain tritium, fission products and other radioactive substances [
1
,
2
]. As a
consequence, man may be exposed to ionizing radiation through various exposure
pathways (Fig.
4.1
):
