PhD Position (M/F) – Development of multifunctional geopolymer materials for radioactive waste conditioning

Job Description

Thesis Subject

Topic : Development of multifunctional geopolymer materials for radioactive waste conditioning

The GEOSHIELD project, funded by the MITI-CNRS 80PRIME program, aims to develop a new generation of low-carbon mineral materials for the conditioning of complex waste, integrating both confinement and radiological shielding functions.

The PhD work will focus on the design and characterization of geopolymer-type materials capable of incorporating contaminated sludges and dense shielding fillers, while ensuring long-term durability.
The main scientific objectives are:
- develop robust formulations integrating radioactive waste and functional fillers (heavy oxides),
- characterize microstructural heterogeneity and interfaces,
- analyze behavior under coupled thermo-hydro-mechano-chemical (THMC) conditions,
- evaluate transport properties and leaching mechanisms,
- study scale-up and material robustness.
The PhD candidate will adopt an integrated approach linking formulation, microstructure, damage, and transport properties, with a view toward the pre-qualification of new waste conditioning matrices.

The candidate should hold (or be about to obtain) a Master's degree (MSc or equivalent) in materials science, civil engineering, geosciences, physical chemistry, or a related field.
Skills or interest in the following areas will be appreciated:
- cementitious or geopolymer materials,
- multiphysics behavior of materials (THMC),
- characterization techniques (microstructure, transfer, mechanics),
- experimental and interdisciplinary approaches.
The candidate should:
- demonstrate a strong interest in the subject, curiosity, and the ability to work independently
- have a good command of English,
- be able to write scientific reports (in French and English) and present results orally,
- be able to work both independently and collaboratively in a national and international team environment.

Your Work Environment

The project is based on a collaboration between:
- SUBATECH (IMT Atlantique, Nantes – IN2P3) : formulation, waste integration, leaching
- LAMCUBE (Centrale Lille – INSIS) : mechanics, durability, transport, and scale-up
The PhD candidate will work in an interdisciplinary environment at the interface of materials science, mechanics, and physico-chemistry of porous media. The candidate will have access to all necessary infrastructure, including analytical chemistry equipment (ICP-MS, IC), nuclear measurement techniques (liquid scintillation, gamma spectrometry), and solid characterization methods through the micro-characterization center at Nantes University.
In addition, the candidate will have access to experimental setups dedicated to THMC coupling studies. These facilities will allow, in particular, the measurement of gas transport properties under thermal and mechanical loading. Finally, an X-ray microtomograph will be available for in operando hydro-mechanical testing, enabling monitoring of microstructural evolution under representative conditions. Advanced imaging techniques (e.g., 3D X-ray tomography, image analysis, and digital volume correlation – DVC) may be used to finely characterize the mechanisms involved.
The project is also part of the European EURAD-2 program (WP STREAM), dedicated to increasing the maturity of conditioning matrices and evaluating them under representative conditions.
The thesis will be conducted in Nantes, within Subatech (Radiochemistry team), in close collaboration with the LaMcube laboratory (Lille).
Extended research stays will be undertaken at the Lille site to conduct experiments and strengthen scientific collaboration between the two teams.
The dissertation will be conducted in Nantes (Subatech), in close collaboration with the LaMcube laboratory (Lille).
Extended research stays will be undertaken at the Lille site to conduct experiments and strengthen scientific collaboration between the two teams.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

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