Urban working groups in the IAEA’s model testing programmes: overview from the MODARIA I and MODARIA II programmes

Abstract

The IAEA’s model testing programmes have included a series of Working Groups concerned with modelling radioactive contamination in urban environments. These have included the Urban Working Group of Validation of Environmental Model Predictions (1988–1994), the Urban Remediation Working Group of Environmental Modelling for Radiation Safety (EMRAS) (2003–2007), the Urban Areas Working Group of EMRAS II (2009–2011), the Urban Environments Working Group of (Modelling and Data for Radiological Impact Assessments) MODARIA I (2013–2015), and most recently, the Urban Exposures Working Group of MODARIA II (2016–2019). The overarching objective of these Working Groups has been to test and improve the capabilities of computer models used to assess radioactive contamination in urban environments, including dispersion and deposition processes, short-term and long-term redistribution of contaminants following deposition events, and the effectiveness of various countermeasures and other protective actions, including remedial actions, in reducing contamination levels, human exposures, and doses to humans. This paper describes the exercises conducted during the MODARIA I and MODARIA II programmes. These exercises have included short-range and mid-range atmospheric dispersion exercises based on data from field tests or tracer studies, hypothetical urban dispersion exercises, and an exercise based on data collected after the Fukushima Daiichi accident. Improvement of model capabilities will lead to improvements in assessing various contamination scenarios (real or hypothetical), and in turn, to improved decision-making and communication with the public following a nuclear or radiological emergency.

Modelling the atmospheric dispersion of radiotracers in small-scale, controlled detonations: validation of dispersion models using field test data

“…Several of the model testing programmes organised by the International Atomic Energy Agency (IAEA) have included Working Groups specifically focused on modelling of radioactive contamination in urban environments (reviewed by Thiessen et al 2008, 2011, 2022, IAEA 1994, 2012a, 2012b, 2021, 2022. One of the areas of interest to these Working Groups has been modelling the dispersion of radioactive contamination from relatively small-scale detonations, which might be relevant for a 'dirty bomb' situation, for example.…”

Assessment of doses in contaminated urban areas: modelling exercise based on Fukushima data

“…The Urban Remediation Working Group of the International Atomic Energy Agency's MODARIA II (Modelling and Data for Radiological Impact Assessments) programme was established in 2016 to develop and test assessment methodologies for remediation of urban areas contaminated with dispersed radionuclides. The overall objective of the MODARIA II Urban Environments Working Group is to test and improve the capabilities of models used in the assessment of radioactive contamination in urban environments (Thiessen et al 2022). The Working Group's scope includes modelling of dispersion and deposition events, short-and long-term redistribution of contaminants following deposition events, and potential countermeasures or remediation measures for reducing human exposures and doses.…”

Studies large and small: the Bernard Wheatley Award for 2022

“…Theissen et al (2022a) described a programme of field studies of atmospheric dispersion undertaken using radioactive tracers (see also Theissen et al (2022b) for the context of these studies). This programme provided a basis for a series of model intercomparison exercises.…”