Post by Ex_Nuke_Troop on May 11, 2014 17:44:07 GMT
European Geosciences Union : Inverse modelling of radionuclide release rates using gamma dose rate
observations
Geophysical Research Abstracts
Vol. 16, EGU2014-14750, 2014
EGU General Assembly 2014
© Author(s) 2014. CC Attribution 3.0 License.
Thomas Hamburger (1), Andreas Stohl (1), Christoph von Haustein (2), Severin Thummerer (2), and Christian
Wallner (2)
(1) Norwegian Institute for Air Research (NILU), Atmospheric and Climate Research (ATMOS), Kjeller, Norway, (2) TÜV
SÜD Industrie Service GmbH, Energie und Technologie, München, Germany
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.
The hazardous consequences reach out on a national and continental scale. Environmental measurements
and methods to model the transport and dispersion of the released radionuclides serve as a platform to assess
the regional impact of nuclear accidents – both, for research purposes and, more important, to determine the
immediate threat to the population.
However, the assessments of the regional radionuclide activity concentrations and the individual exposure to
radiation dose underlie several uncertainties. For example, the accurate model representation of wet and dry
deposition. One of the most significant uncertainty, however, results from 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 terms of severe nuclear accidents may either remain uncertain (e.g.
Chernobyl, Devell et al., 1995) or rely on rather rough estimates of released key radionuclides given by the
operators. Precise measurements are mostly missing due to practical limitations during the accident.
Inverse modelling can be used to realise a feasible estimation of the source term (Davoine and Bocquet, 2007).
Existing point measurements of radionuclide activity concentrations are therefore combined with atmospheric
transport models. The release rates of radionuclides at the accident site are then obtained by improving the
agreement between the modelled and observed concentrations (Stohl et al., 2012). The accuracy of the method
and hence of the resulting source term depends amongst others on the availability, reliability and the resolution
in time and space of the 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. Gamma
dose rate measurements contain no explicit information on the observed spectrum of radionuclides and have to be
interpreted carefully. Nevertheless, they provide valuable information for the inverse evaluation of the source term
due to their availability (Saunier et al., 2013).
We present a new inversion approach combining 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 gamma dose rates are calculated from the modelled activity concentrations.
The inversion method uses a Bayesian formulation considering uncertainties for the a priori source term and the
observations (Eckhardt et al., 2008). The a priori information on the source term is a first guess. The gamma dose
rate observations will be used with inverse modelling to improve this 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.
meetingorganizer.copernicus.org/EGU2014/EGU2014-14750.pdf
The EGU General Assembly 2014 brings together over 11,000 geoscientists from all over the world into one meeting covering all disciplines of the Earth, planetary and space sciences. It provides an opportunity for journalists and science writers to learn about new developments in a variety of topics including climate change, recent space and planetary science missions, natural disasters, ocean acidification, rare-earth minerals, ice loss and sea-level rise among others.
The 2014 Assembly is taking place at the Austria Center Vienna from 27 April to 2 May and, for the first time, it will have a theme: The Face of the Earth – Process and Form. The theme intends to celebrate the diversity of geoscience processes and the great variety of associated forms, across all scales and from the core of the Earth to interplanetary space.
media.egu.eu
observations
Geophysical Research Abstracts
Vol. 16, EGU2014-14750, 2014
EGU General Assembly 2014
© Author(s) 2014. CC Attribution 3.0 License.
Thomas Hamburger (1), Andreas Stohl (1), Christoph von Haustein (2), Severin Thummerer (2), and Christian
Wallner (2)
(1) Norwegian Institute for Air Research (NILU), Atmospheric and Climate Research (ATMOS), Kjeller, Norway, (2) TÜV
SÜD Industrie Service GmbH, Energie und Technologie, München, Germany
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.
The hazardous consequences reach out on a national and continental scale. Environmental measurements
and methods to model the transport and dispersion of the released radionuclides serve as a platform to assess
the regional impact of nuclear accidents – both, for research purposes and, more important, to determine the
immediate threat to the population.
However, the assessments of the regional radionuclide activity concentrations and the individual exposure to
radiation dose underlie several uncertainties. For example, the accurate model representation of wet and dry
deposition. One of the most significant uncertainty, however, results from 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 terms of severe nuclear accidents may either remain uncertain (e.g.
Chernobyl, Devell et al., 1995) or rely on rather rough estimates of released key radionuclides given by the
operators. Precise measurements are mostly missing due to practical limitations during the accident.
Inverse modelling can be used to realise a feasible estimation of the source term (Davoine and Bocquet, 2007).
Existing point measurements of radionuclide activity concentrations are therefore combined with atmospheric
transport models. The release rates of radionuclides at the accident site are then obtained by improving the
agreement between the modelled and observed concentrations (Stohl et al., 2012). The accuracy of the method
and hence of the resulting source term depends amongst others on the availability, reliability and the resolution
in time and space of the 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. Gamma
dose rate measurements contain no explicit information on the observed spectrum of radionuclides and have to be
interpreted carefully. Nevertheless, they provide valuable information for the inverse evaluation of the source term
due to their availability (Saunier et al., 2013).
We present a new inversion approach combining 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 gamma dose rates are calculated from the modelled activity concentrations.
The inversion method uses a Bayesian formulation considering uncertainties for the a priori source term and the
observations (Eckhardt et al., 2008). The a priori information on the source term is a first guess. The gamma dose
rate observations will be used with inverse modelling to improve this 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.
meetingorganizer.copernicus.org/EGU2014/EGU2014-14750.pdf
The EGU General Assembly 2014 brings together over 11,000 geoscientists from all over the world into one meeting covering all disciplines of the Earth, planetary and space sciences. It provides an opportunity for journalists and science writers to learn about new developments in a variety of topics including climate change, recent space and planetary science missions, natural disasters, ocean acidification, rare-earth minerals, ice loss and sea-level rise among others.
The 2014 Assembly is taking place at the Austria Center Vienna from 27 April to 2 May and, for the first time, it will have a theme: The Face of the Earth – Process and Form. The theme intends to celebrate the diversity of geoscience processes and the great variety of associated forms, across all scales and from the core of the Earth to interplanetary space.
media.egu.eu