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| Titel |
Inverse modelling of radionuclide release rates using gamma dose rate observations |
| VerfasserIn |
Thomas Hamburger, Nikolaos Evangeliou, Andreas Stohl, Christoph von Haustein, Severin Thummerer, Christian Wallner |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104408
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| Publikation (Nr.) |
 EGU/EGU2015-3828.pdf |
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| Zusammenfassung |
| Severe accidents in nuclear power plants such as the historical accident in Chernobyl 1986 or
the more recent disaster in the Fukushima Dai-ichi nuclear power plant in 2011 have drastic
impacts on the population and environment. Observations and dispersion modelling
of the released radionuclides help to assess the regional impact of such nuclear
accidents.
Modelling the increase of regional radionuclide activity concentrations, which results from
nuclear accidents, underlies a multiplicity of uncertainties. One of the most significant
uncertainties is the estimation of the source term. That is, the time dependent quantification
of the released spectrum of radionuclides during the course of the nuclear accident. The
quantification of the source term may either remain uncertain (e.g. Chernobyl, Devell et
al., 1995) or rely on estimates given by the operators of the nuclear power plant.
Precise measurements are mostly missing due to practical limitations during the
accident.
The release rates of radionuclides at the accident site can be estimated using inverse
modelling (Davoine and Bocquet, 2007). The accuracy of the method depends amongst
others on the availability, reliability and the resolution in time and space of the used
observations. Radionuclide activity concentrations are observed on a relatively sparse grid
and the temporal resolution of available data may be low within the order of hours or a day.
Gamma dose rates, on the other hand, are observed routinely on a much denser grid and
higher temporal resolution and provide therefore a wider basis for inverse modelling (Saunier
et al., 2013).
We present a new inversion approach, which combines an atmospheric dispersion model and
observations of radionuclide activity concentrations and gamma dose rates to obtain the
source term of radionuclides. We use the Lagrangian particle dispersion model
FLEXPART (Stohl et al., 1998; Stohl et al., 2005) to model the atmospheric transport
of the released radionuclides. The inversion method uses a Bayesian formulation
considering uncertainties for the a priori source term and the observations (Eckhardt et
al., 2008, Stohl et al., 2012). The a priori information on the source term is a first
guess. The gamma dose rate observations are used to improve the first guess and to
retrieve a reliable source term. The details of this method will be presented at the
conference.
This work is funded by the Bundesamt für Strahlenschutz BfS, Forschungsvorhaben
3612S60026.
References
Davoine, X. and Bocquet, M., Atmos. Chem. Phys., 7, 1549–1564, 2007.
Devell, L., et al., OCDE/GD(96)12, 1995.
Eckhardt, S., et al., Atmos. Chem. Phys., 8, 3881–3897, 2008.
Saunier, O., et al., Atmos. Chem. Phys., 13, 11403-11421, 2013.
Stohl, A., et al., Atmos. Environ., 32, 4245–4264, 1998.
Stohl, A., et al., Atmos. Chem. Phys., 5, 2461–2474, 2005.
Stohl, A., et al., Atmos. Chem. Phys., 12, 2313–2343, 2012. |
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