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Reference : UMR9012-REJBOD-019
Workplace : ORSAY
Date of publication : Tuesday, September 15, 2020
Scientific Responsible name : Céline CANNES
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 November 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Reactivity of the steel container of the nuclear waste primary package in contact with magnesium phosphate cements.
Keywords: new conditioning matrix, cement formulation, cement characterization, steel corrosion.
The legacy nuclear facilities have to be decommissioned. Concrete encapsulation is one strategy to manage the low level (LL) and intermediate level (IL) waste. However, the major risk is the corrosion of metal compounds (nuclear waste and container) by interstitial water, resulting in hydrogen release. The European project PREDIS proposes magnesium phosphate cements (MPC) as alternative systems to the conventional Portland cements to condition the LL and IL radioactive waste. In this context, the PhD work will concern the knowledge on magnesium phosphate cements and the reactivity of the steel container in contact with this new conditioning matrix.
Currently, research on MPC has been carried out at the laboratory scale by using raw materials of high purity from a few providers. Their price ranges from 50 to 100 times more expensive than the price of conventional cement for matrix confinement. One goal of this project is to decrease the MPC cost to envisage their use at the industrial scale, while keeping the material properties defined by the waste acceptance criteria.
Pastes and mortars will be prepared with the chosen raw materials and will be fully characterized: both early age (heat of hydration, setting time) and long-term behaviour (durability), their mechanical properties (shrinkage, swelling) and their microstructure (porosity, diffusion, formation and stability of the solid phases). Electrochemical analysis recently developed by IJCLab based on in situ measurement will be used to study the time evolution of the matrices. It is important to ensure that the physico-chemical properties of the matrix do not change because of the presence of impurities.
Since steel drums are widely used containers for cemented waste, the objective is to determine its reactivity in contact with MPC. The steel corrosion will then be investigated in the MPC with the best formulation for Al (one of the LL radioactive waste) encapsulation and in the cement with the lowest cost. Electrochemical measurements, chromatographic H2 titration and steel surface characterization will be undertaken to determine the corrosion mechanism of steel in MPC, to evaluate the H2 production and the degradation of the drum.
'Selection of a mineral binder with potentialities for the stabilization/solidification of aluminum metal', C. Cau Dit Coumes, D. Lambertin, H.
Lahalle, P. Antonucci, C. Cannes, S. Delpech, J. Nucl. Mat. 453 (2014) 31-40.
'Investigation of magnesium phosphate cement hydration and its retardation by boric acid' H. Lahalle, C. Cau Dit Coumes, A. Mesbah, D.
Lambertin, C. Cannes, S. Delpech, A. Nonat, S. Gauffinet, Cem. Concr. Res. 87 (2016) 77-86.
'Kinetic Model of Aluminum Behavior in Cement-Based Matrices Analyzed by Impedance Spectroscopy' S. Delpech, C. Cannes, N. Barré,
Q. Thuan Tran, H. Lahalle, D. Lambertin, S. Gauffinet, C. Cau Dit Coumes, J. Electrochem. Soc. 164 (2017) C717-C727.
'Influence of the w/c ratio on the hydration process of a magnesium phosphate cement and on its retardation by boric acid', H. Lahalle, C.
Cau Dit Coumes, C. Mercier, D. Lambertin, C. Cannes, S. Delpech, S. Gauffinet, Cem. Concr. Res. 109 (2018) 159-174.
'Role of fluoride ions on the uranium oxidation mechanism in highly alkaline solutions', D. Rodrigues, C. Cannes, N. Barre, D. Lambertin, S.
Delpech, Electrochim. Acta 266 (2018) 384-394.
'Reactivity of uranium in geopolymers, confinement matrices proposed to encapsulate Mg-Zr waste' C. Cannes, D. Rodrigues, N. Barré, D.
Lambertin, S. Delpech, J. Nucl. Mater. 518 (2019) 370-379.
The Irène Joliot-Curie Physics Laboratory of 2 Infinities (IJCLab) is a UMR under the supervision of the CNRS (IN2P3), the University of Paris-Saclay and the University of Paris. IJCLab is located on the campus of the University of Paris -Saclay in Orsay (20 km south of Paris and easily accessible by RER in 35 min.). IJCLab was born in 2020 from the merger of five units (CSNSM, IMNC, IPN, LAL, LPT). The staff is made up of nearly 560 permanents (340 engineers, technicians and administrators and 220 researchers and teacher-researchers) and approximately 200 non-permanents including 120 doctoral students. The research themes of the laboratory are nuclear physics, high energy physics, theoretical physics, astroparticles, astrophysics and cosmology, particle accelerators, energy and the environment and health. IJCLab has very significant technical capacities (around 280 IT) in all the major fields required to design, develop / implement the experimental devices necessary for its scientific activity, as well as the design, development and use of instruments.
The PhD student will be enrolled at the Doctoral School Particules, Hadrons, Energie, Noyau, Instrumentation, Imagerie, Cosmos et Simulation (PHENIICS) of the University Paris Saclay. The scientific domains of PHENIICS include particle physics, nuclear physics, cosmology and astrophysics, nuclear energy, and theoretical physics particularly where there is a strong dialog with experiment (phenomenology, quantum field theory, gravitation, the N-body problem, etc). A vibrant instrumentation program covers accelerator and detector physics, including simulations and optimization. The applications and societal aspects of these domains, like radiochemistry and medical imaging, round out the PHENIICS offering and provide a multifaceted educational experience for the doctoral students of the University of Paris-Saclay. The subject of the thesis is involved in the “Nuclear Energy” topic as it concerns the management of nuclear waste.
This thesis will be carried out in the frame of the European project PREDIS. The work will be realized in the « Energy and Environment » division of the IJCLab in the CHIMèNE team (Chimie, Irradiation, Matériaux, Modélisations, Electrochimie pour le Nucléaire et l'Environnement) in collaboration with ORANO. The project will be divided into two parts. The goal of the first part is to decrease the cost of a new conditioning matrix, constituted of magnesium phosphate cements. For this part, the PhD student will take advantage of the expertise of ORANO and IJCLab on the nuclear waste and the conditioning matrices. A collaboration will be established with the CEA Marcoule (Bagnols-sur-Cèze) to characterize the cements prepared according to different formulations (heat of hydration, setting time, mechanical resistance…). The second part will concern the reactivity of the steel primary package in contact with the magnesium phosphate cements. This work will be achieved at IJCLab according to a scientific approach developed these last years based on studies in solutions mimicking the pore solution of the cements and studies in situ in cements. A team at IJCLab works since 2012 on the conditioning of nuclear waste in cementitious matrices and has set up the required equipment to undertake these studies (potentiostats, gas chromatography, ICP/AES, XRD, confocal microscopy). The simulation codes to interpret the experimental results have also been developed in this institute.
Constraints and risks
This PhD thesis will form part of a European project for which a schedule of the work has been planned. Some partners have been engaged in studies on “low-cost” magnesium phosphate cements (irradiation and resaturation effect, corrosion of different metal waste incorporated in these cements). The PhD student will then have to follow this schedule and notably will have to propose to the other partners a « low-cost” formulation for these new matrices at the end of the second year of the project.
The work will be mainly carried out at IJCLab (Orsay, France) but secondment at the CEA (Bagnols-sur-Cèze, France) of approximately one month's duration should be expected at the end of the first year. The cost of this secondment will be paid by the IJCLab. Travel to participate to congress or to the European project meetings will also be expected.
The candidate must have a research master degree in nuclear energy, analytical chemistry, electrochemistry or materials chemistry. The post requires skills in aqueous and non-aqueous solution, thermodynamic calculation, electrochemistry, materials chemistry (techniques of surface characterization).
The candidate must also have a high level in communication, both oral and written (in French AND English) to present his results at the lab meeting, the European project meeting and the international congress but also to write the deliverables due for the European project, articles in international scientific journals and his manuscript of thesis. We are looking for a young researcher who will be able to become fully involved in the project, who will show interest in nuclear waste management. The candidate should present an autonomy and a high level of motivation to develop skills in the topic of metallic waste conditioning in cementitious matrices. Moreover, the student will be able to work in a team by using the different available techniques to perform the project. The candidate will must adapt to the different environments and will have to manage this collaborative project.
The candidates will have to provide a detailed CV, a cover letter of one page; a one-page résumé of the dissertation for the Masters; grades for the Masters 1 or 2.
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