Nuclear waste management

Permanent staff: Céline Cannes, Sylvie Delpech, Davide Rodrigues

Description of the research activities

The operation and decommissioning of the nuclear facilities generate a large volume of radioactive metallic wastes, which have to be managed as a function of their radioactivity level and their lifetime. The conditioning of metallic waste of low and intermediate level consists in their encapsulation in a cement in a drum to limit the corrosion with water and dioxygen. However, some metallic wastes are too reactive in the usual matrices like Portland cements and so hydrogen is produced by aqueous corrosion. The eligible H2 amounts in the storage site correspond to the concentration of the explosive limit or to the pression increase, which can lead to the damage of the package and so to the loss of the radioactivity confinement. New matrices, such as the magnesium phosphate cements and the geopolymers are under study (formulations, reactivity of metals in these media) to evaluate the risks generated during the conditioning and to reduce the H2 production inside the package.

Several projects of this topic within the CHIMèNE team concerned the reactivity on cementitious matrices of the metal waste generated during the dismantling of Natural Uranium Graphite Gas reactors (Al, Al-Mg, MgZr) and the waste generated by fusion reactors (Be, W). The reactivity of the steel drum was evaluated in cementitious media. Projects were also devoted to the development of cement formulations, either to reduce the cost of manufacturing conditioning matrices, or to recover depleted uranium, by developing high-performance concretes for different applications. The problem of nuclear waste in the form of powders, exhibiting increased reactivity, is now being studied. It is envisaged to dissolve the metal powders in molten hydroxides at 250 °C. The solution obtained can then be used to prepare the conditioning matrix. 

Collaborations

  CEA, ORANO, partners of the PREDIS project

Former post-doctoral contracts

  • Kim Le, Reactivity of the steel of the primary package of radioactive metallic waste in contact with phosphomagnesium cements, Projet européen PREDIS, 09/2021-12/2023.
  • Elodie Lacroix, Preparation of high-performance concretes based on depleted uranium, Projet France 2030 MAEVA, 11/2022-04/2024.

Defended PhD thesis

  • Richard Laflotte, Etude du béryllium dans les matrices cimentaires en présence de piégeurs à hydrogène (Centrale Lille, CEA funding, 2021-2024).
  • Gabriel Poras, Study of the conditioning of aluminum alloys in a matrix based on phospho-magnesium cement, CEA funding, Université de Montpellier, 2023.
  • Pauline Bouhier, Comparative study of Be and its simulants for its conditioning in a cement matrix, CEA funding, Université Paris-Saclay, 2022.
  • Hugo Lahalle, Conditioning of metallic aluminum in phospho-magnesium cements, CEA funding, Université de Bourgogne, 2016.

Last publications

  • P. Bouhier, C. Cannes, D. Lambertin, C. Grisolia, D. Rodrigues, S. Delpech, Evaluation of several conditioning matrices for the management of radioactive metal beryllium wastes. J. Nucl. Mat. 559 (2022) 153464
  • C. Cannes, D. Rodrigues, N. Barré, D. Lambertin, S. Delpech, Reactivity of uranium in geopolymers, confinement matrices proposed to encapsulate Mg-Zr waste. J. Nucl. Mater. 518 (2019) 370-379
  • D. Rodrigues, C. Cannes, N. Barre, D. Lambertin, S. Delpech. Role of fluoride ions on the uranium oxidation mechanism in highly alkaline solutions. Electrochim. Acta 266 (2018) 384-394
  • Hugo Lahalle, Céline Cau Dit Coumes, Cyrille Mercier, David Lambertin, Céline Cannes, Sylvie Delpech, Sandrine Gauffinet. Influence of the w/c ratio on the hydration process of a magnesium phosphate cement and on its retardation by boric acid. Cem. Concr. 109 (2018) 159-174
  • S. Delpech, C. Cannes, N. Barré, Q. Thuan Tran, H. Lahalle, D. Lambertin, S. Gauffinet, C. Cau Dit Coumes. Kinetic Model of Aluminum Behavior in Cement-Based Matrices Analyzed by Impedance Spectroscopy. J. Electrochem. Soc. 164 (2017) C717-C727
  • H. Lahalle, C. Cau Dit Coumes, A. Mesbah, D. Lambertin, C. Cannes, S. Delpech, A. Nonat, S. Gauffinet. Investigation of magnesium phosphate cement hydration and its retardation by boric acid. Cem. Concr. Res. 87 (2016) 77-86
  • C. Cau Dit Coumes, D. Lambertin, H. Lahalle, P. Antonucci, C. Cannes, S. Delpech. Selection of a mineral binder with potentialities for the stabilization / solidification of aluminum metal. J. Nucl. Mat. 453 (2014) 31-40