Civil Engineering Reference
In-Depth Information
iodine nuclides. Internal
-exposures and subsequent organ doses also
follows the ingestion of contaminated food and drinking water.
Inhalation of deposited and then resuspended nuclides plays a secondary role in
moderate climate zones, such as Central Europe, unless the released material
consists mainly of
α
-,
β
-, and
γ
α
-emitters.
Once radioactive substances have entered the body, they become excreted or
stay in the blood stream or organs or tissues for different periods of time. As long as
they remain in the body they give rise to the so called “committed dose” which is
defined as the dose for adults and children resulting from internal exposure over a
period of 50 and 70 years, respectively.
Doses evaluated without taking into account any shielding effects or actions for
avoiding or mitigating exposure are referred to as a “potential doses.” For instance,
the dose calculated from external
-radiation, inhalation, and contamination of
clothes under the assumption of permanent unprotected residence in the open air
is a “potential dose” (also called “open air dose)”. Actual doses may differ from the
potential ones; this depends on the surroundings and thus on the lifestyle habits of
the considered individuals. Doses derived by assuming some representative average
lifestyle are called “normal living doses”.
The total dose rate that results from
γ
-exposure from the cloud and from the
ground or other contaminated surfaces is referred to as the “local (
γ
-)dose rate”; it
is mostly expressed in terms of micro Sievert or nano Sievert per hour
(
γ
10
9
Sv/h, respectively). The German Federal
Office for Radiation Protection operates an automatic local
10
6
Sv/h and nSv/h
μ
Sv/h
¼
¼
-dose rate measuring
network as part of the German IMIS system with approximately 2,000 measuring
points. According to this measuring network, the average natural local
γ
γ
-dose rate
in Germany is about 0.1
Sv/h, roughly corresponding to an annual dose of 1 mSv.
Significant deviation from the average natural background level may be the first
indicator that a nuclear accident is going on. In case of a real accident, a comparison
of readings from stationary networks or mobile monitors with computed local
γ
μ
-dose rate values allows conclusions about the source term and the real atmo-
spheric transport situation.
20.2 Effects on Health from Radiation Exposure
This chapter briefly recapitulates the phenomena and terms in connection with the
possible effects on health from radiation exposure. Information about radiation
damage also for non-experts can be found for example on web sites of national
health offices.
2
2
In German see e.g. the web site of the German Federal Office for Radiation Protection, http://
www.bfs.de/. In English see e.g. the web site of the American CDC Centers for Disease Control
and Prevention,
http://www.bt.cdc.gov/radiation/glossary.asp
