Missions

Numerical simulation of radionuclide dispersion in the atmosphere is subject to significant uncertainties, mainly related to the input data: weather forecasts and the source term. To represent meteorological uncertainty, ensemble forecasts have been used as input to atmospheric dispersion models to simulate the consequences of a nuclear accident (Korsakissok et al., 2020, Le et al., 2021). Clustering techniques, which select a few representative forecasts from the ensemble, have also been developed (El-Ouartassy et al., 2022) to reduce the computational time associated with these simulations, while predicting "risk zones" that can be used for decision-making.
The objective of this thesis is to develop an atmospheric dispersion modeling chain integrating the different sources of uncertainty, in the event of accidental releases of pollutants, and taking into account operational constraints of calculation time and relevant criteria for crisis management. This thesis is part of the Natech project of PEPR Risks. The framework of application of the thesis will be a multi-risk scenario on a pilot site in Gironde. The results of the thesis, and the forecast products that will result from it, will feed into research and workshops with stakeholders.

Activités

The first step will be to take control of Météo France's ensemble forecast models and validate them in the geographical area of ​​interest for the thesis (Gironde estuary), for one or more selected meteorological situations, including storm events. The student will then develop a complete calculation chain, including ensemble weather forecasts, a source term (temporal evolution of the release rates of different radionuclides into the atmosphere, emission height, initial temperature) and the associated uncertainties, and the ASNR pX atmospheric dispersion model.
The clustering method developed in El-Ouartassy et al. (2022) will be adapted and evaluated on the case study. It will be improved in several aspects, on the one hand to take into account precipitation and uncertainties related to the source term, and on the other hand to integrate criteria adapted to operational decision-making in the territory, such as population density, the presence of critical infrastructure or agricultural issues. The simulations will provide risk forecast maps, which can be presented to decision-makers and stakeholders in the territory, and as part of workshops on crisis management and the link between expertise and decision-making. Work on the visualization of forecast uncertainties will be carried out: this will involve presenting, in a simple and intelligible form, the different possible scenarios and the associated risks and issues. The results of the workshops will help guide and enrich the modeling and visualization chain developed, by including criteria relevant to crisis management.
Finally, a multi-risk simulation, combining nuclear and industrial accidents in a marine submersion context, will be carried out with the Natech project partners, notably Ineris (industrial risk) and the University of Bordeaux (submersion). The developments made during the thesis must be compatible with integration into the IRIMA integrated risk management platform and allow for good interoperability.

Compétences

- Very good command of computer programming (especially Python)
- Experience in handling large data sets
- Good knowledge and practice of machine learning methods (especially clustering methods)
- Ability to work in an interdisciplinary manner, with remote collaborators
- Good command of English, read, written, spoken
- Ability to communicate results - Knowledge of atmospheric physics would be a plus

Contexte de travail

The thesis will be carried out at the CNRM, in Toulouse, and will be co-supervised by the ASNR. Occasional trips to the ASNR in Fontenay-aux-Roses, as well as during PEPR scientific meetings and seminars

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.