Civil Engineering Reference
In-Depth Information
Meteorological input of varying quantity and quality is possible, ranging from
meteorological data applying for a given location entered by hand, over data
measured at a nuclear power plant by means of a meteorological tower or sound/
sonic detecting and ranging (SODAR) equipment, to extensive data fields from
numerical weather forecast models. The preprocessor converts the input data into
meteorological fields on the entire computation grid, applying a diagnostic (mass-
consistent) flow model for refining the resolution and taking into account topo-
graphic factors.
The models available for atmospheric dispersion and deposition calculations
over a range of up to about a few hundred km are the Gaussian puff models
ATSTEP [
7
] and RIMPUFF [
8
] as well as the particle models DIPCOT [
6
] and
LASAT [
9
]. For larger distances, Germany applies the Lagrange particle dispersion
model, LPDM [
10
] of the German Weather Service, and other countries the
Eulerian grid model, MATCH [
11
].
The multitude of diffusion models in RODOS results on the one side from the
historic development of the system as a joint European effort, and on the other side
from the different levels of performance and ranges of application of the models.
The model properties were verified in comparative and validation studies [
12
]. For
the future, it is considered to cover all requirements (especially a sufficiently short
computation time) with one single short-range model, if possible.
21.2.1.3 The Model for Early Countermeasures, EmerSim
With the EmerSim model [
13
], the need and the extent of early countermeasures
and the effects of such actions on doses are determined, aiming at the optimization
of early countermeasure strategies. A strategy scenario in EmerSim consists of a
combination of three specific actions: Staying indoors; evacuation; taking iodine
tablets. In a first step, those areas are estimated where the potential doses—that is,
the doses without consideration of actions for avoiding or reducing exposure—
exceed the respective intervention levels. In a second step, the dose reduction by the
actions is simulated in these areas by applying location- and time-dependent
shielding factors for the respective actions. The calculations result in time series
of modified organ doses for all cells of the calculation grid that can be compared
with the potential doses. Comparing the numbers of people in given dose ranges
without any action and with different countermeasure strategies provides a measure
for the radiological effectiveness, thus helping to discern between the strategies.
EmerSim can be applied in many countries, as the database includes
corresponding country-specific intervention levels and dose criteria for early
countermeasures.
