Numerical simulations of atmospheric dispersion of iodine-131 by different models

Abstract

Nowadays, several dispersion models are available to simulate the transport processes of air pollutants and toxic substances including radionuclides in the atmosphere. Reliability of atmospheric transport models has been demonstrated in several recent cases from local to global scale; however, very few actual emission data are available to evaluate model results in real-life cases. In this study, the atmospheric dispersion of 131I emitted to the atmosphere during an industrial process was simulated with different models, namely the WRF-Chem Eulerian online coupled model and the HYSPLIT and the RAPTOR Lagrangian models. Although only limited data of 131I detections has been available, the accuracy of modeled plume direction could be evaluated in complex late autumn weather situations. For the studied cases, the general reliability of models has been demonstrated. However, serious uncertainties arise related to low level inversions, above all in case of an emission event on 4 November 2011, when an important wind shear caused a significant difference between simulated and real transport directions. Results underline the importance of prudent interpretation of dispersion model results and the identification of weather conditions with a potential to cause large model errors.

Bayesian inverse modeling and source location of an unintended <sup>131</sup>I release in Europe in the fall of 2011

“…The fourth source of uncertainty is the input data from meteorological reanalysis. As shown by Leelőssy et al (2017), the example meteorological situation on 4 November in 2011 in central Europe was very complex with low-level inversion where the winds below the inversion level were significantly different than the winds above. Subsequently, if boundary layer heights were systematically too high, simulated ground-level concentrations may be systematically too low.…”

“…This would be probably compensated by the inversion with a too large emitted amount. In these and other complex situations, different models may provide very different performances (Leelőssy et al, 2017).…”

“…For instance, simulations with atmospheric transport models were used previously to study the distribution of radioactive material after the Chernobyl (e.g., Brandt et al, 2002;Davoine and Bocquet, 2007) and Fukushima Dai-ichi nuclear accidents (e.g., Morino et al, 2011;Stohl et al, 2012;Saunier et al, 2013). Simulations were also already made for the 131 I release from IoI in 2011 (Leelőssy et al, 2017). However, the agreement between the results of simulations and real measurements needs to be carefully evaluated since simulations often suffer from inaccuracies in meteorological input data or model parameterizations.…”

A kémiai mechanizmusok szerepe a levegominoség-modellezésben

“…A WRF-Chem modellel korábbi futtatásaink során aeroszol részecskék terjedését vizsgáltuk városi (Kovács et al, 2016), valamint regionális skálán (Leelőssy et al, 2017).…”

Bayesian inverse modeling and source location of an unintended I-131 release in Europe in the fall of 2011

“…For instance, simulations with atmospheric transport models were used previously to study the distribution of radioactive material after the Chernobyl (Brandt et al, 2002;Davoine and Bocquet, 2007) and Fukushima Dai-ichi nuclear accidents (Morino et al, 2011;Stohl et al, 2012;Saunier et al, 2013). Simulations were also already made for the I-131 release from IoI in 2011 (Leelőssy et al, 2017). However, the agreement between the results of simulations and real measurements needs to be carefully 25 evaluated since simulations often suffer from inaccuracies in meteorological input data or model parametrizations.…”