Civil Engineering Reference
In-Depth Information
Table 20.1
Mean shielding factors in use in RODOS
Semi-detached
or terraced
houses
Multi-storey
block
building
Shielding factor
against
Open air (without trees or
buildings in the vicinity)
Lightweight flat
module building
Ground
γ
1.0
0.5
0.1
0.01
-irradiation
Cloud
γ
1.0
0.8
0.5
0.2
-irradiation
Inhalation from
the cloud
1.0
0.5
0.5
0.5
many countries there are age limits for the application of this measure; e.g. in
Germany where tablets are not distributed if the age exceeds 45 years.
Measures associated with the ingestion pathways can be issued either as
non-binding precautionary warnings and recommendations irrespective of any
threshold levels, for example, warnings against the intake of locally produced
freshly harvested food, or the requests to put grazing cattle off pasture and on
uncontaminated feed if possible. Such measures can be taken already in the early
phase.
Binding interventions into the supply of food and feed stuffs, however, must be
issued on the basis of maximum permitted activity levels, and play a major role only
in the later phase after an accident.
20.3.3.2 Late-Phase Measures in Urban and Rural Areas
The primary measure for protecting the general public against external irradiation
from activity deposited onto the ground and other surfaces in the post-release phase
is relocating the people from the area, either temporarily for weeks or months, or
permanently for an indefinite period of time. In general, relocation will be initiated
only when measured data for the entire area are available.
Aside from relocation, in the post-release phase there are on the one hand
agricultural measures with the aim of mitigating the uptake of radioactivity via
contaminated food and drinking water, and on the other hand decontamination and
other measures in urban environments with the aim of reducing daily life exposure
of the general public.
After the Chernobyl accident in 1986, Europe undertook the effort of systemat-
ically identifying and cataloguing all decontamination and rehabilitation measures
which could reasonably be applied in Europe following a nuclear or a radiological
event [
4
]. The survey yielded in roughly 100 measures, and a range of typical
criteria that allow selecting the most appropriate ones from the list:
• Extension of the contamination in space and time
• Effectiveness of a measure
• Amount and treatment of generated waste
