Soutenance de thèse
Thermal decomposition of bitumen and nitrate-based bituminous mixes: anexperimental–numerical study demonstrating the predictive potential of a kinetic model (DAEM)
Soutenance de thèse par Ali HODROJ.
- 09h15
- 10 avril 2026
- Auditorium ICSM, Institute Chemistry Séparative De Marcoule, Centre de Marcoule, 30207 Bagnols-sur-Cèze
La thèse a été dirigée par Monsieur Patrick PERRÉ et co-encadrés par Messieurs Nicolas COURTOIS et Simon DELCOUR
Le jury sera composé de :
| Mme Sophie DUQUESNE, Professeure des universités, Centrale Lille Institut, FRANCE | Rapporteuse |
| M. Patrick VAN HEES, Professeur, Lund University, SUÈDE | Rapporteur |
| M. Abdenour AMOKRANE, Ingénieur de recherche, EDF R&D Lab Chatou, FRANCE | Examinateur |
| M. Damien MARQUIS, Ingénieur de recherche, National laboratory of metrology and testing (LNE), FRANCE | Examinateur |
| M. Jose L. TORERO CULLEN, Professeur, University College London, ROYAUME-UNI | Examinateur |
| M. Antony DUFOUR, Directeur de recherche, Université de Lorraine, FRANCE | Examinateur |
Abstract:
In the 1960s, bitumen was chosen by the French nuclear industry as a matrix for immobilizing low- and intermediate-level radioactive products generated during nuclear fuel reprocessing. Currently, in France, storage facilities temporarily house several thousand tons of bituminized waste, awaiting final disposal. Their management raises safety questions regarding the thermal behavior of bitumen, which is flammable, and the possible interactions between bitumen and embedded salts (especially nitrates). These concerns are currently being addressed through a safety procedure led by French BWP producers, including the French Atomic Energy Commission (CEA) and the industrial partner ORANO, to ensure the safety of storage and disposal facilities and mitigate fire hazards. The main safety concerns are associated with low temperatures below decomposition temperatures. Studies conducted to understand thermal degradation and burning characteristics of bituminous mixes are useful for consolidating our understanding of physicochemical mechanisms above those temperatures, yet such studies remain limited.
This is the reason why a study was conducted to assess the thermal and combustion behavior of pure bitumen and model nitrate-based bituminized mixes. The objective of this research study is structured around two approaches: an experimental axis and a numerical axis, and has been divided into the following tasks: Initially, the study investigated the thermolysis behavior of pure bitumen, and two model nitrate-based mixes (magnesium nitrate hydrate and sodium nitrate) at matter scale using thermogravimetry coupled with differential thermal analyses, and distribution activation energy model (DAEM) was proposed to describe their thermal decomposition at any temperature-time profiles. Subsequently, the analysis is extended to the material scale, where the burning behavior of the studied materials was investigated using a cone calorimeter under well-ventilated and oxygen-depleted conditions, assessing the effects of varying oxygen concentrations and external heat fluxes on both their condensed and gaseous phases. Finally, a pyrolysis model was proposed and implemented by coupling the kinetic sub-model (DAEM) with a heat transfer model to demonstrate its upscaling potential, enabling the numerical prediction of bitumen decomposition under a cone calorimeter.
The results provide a comprehensive analysis of the thermal and combustion behavior of bitumen and bituminized mixes under different scenarios. Experimental observations enable an in-depth understanding of the key thermo-chemical processes. The kinetic parameters were successfully described using DAEM, demonstrating excellent predictive accuracy across the investigated conditions at the matter scale. The model effectively captures the complexity of the thermal decomposition behavior of the studied materials and shows good predictions when implemented within a one-dimensional pyrolysis model.