Glass - Back to the Future!

Presenting Author:
Stéphane Lemonnier

article posted 27 April 2016

Stéphane Lemonnier I’m a doctor scientist in inorganic material chemistry for the CEA (The French Alternative Energies and Atomic Energy Commission) in France. I’m working in the Vitrification Process Development Laboratory for 10 years. I’m in charge of demonstration runs on Cold Crucible Induction Melter or Joule Heated Metallic Melter platforms located at the Marcoule Site.

Development of In-Can Melting Process Applied to the vitrification of High Activity Waste Solutions (HAWS): Glass characterization and process tests results

S. Lemonnier*, I. Hugon, M. Delaunay, Y. Papin, J. Lacombe, O. Pinet, C. Girold
Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), CEA Marcoule BP 17171, 30207 Bagnols sur Cèze
Ariane Lecas-Hardit, Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), CEA Valduc 21120 Is-sur-Tille

The French Alternative Energies and Atomic Energy Commission (CEA) has selected vitrification to treat a fraction of its nuclear waste arising from its activities. This choice has led the CEA Marcoule to develop both a glass composition domain adapted for two types of waste solutions containing large quantity of salts, and a compact “in-can” batch direct liquid fed melting process, in which the melting pot is disposable and serves as the primary canister for the solidified glass. This process is particularly suitable for the treatment of small waste quantities (less than 10 m3 per year) and low flow rates (5 to 10 L/h).

This paper is an overview of the material and the process qualification program begun in 2009, and which is about to be completed in 2016.

At the laboratory scale, a glass matrix composition domain was determined using design of experiment protocol, and glass was characterized in terms of physic and chemical properties (viscosity, density, glass transition temperature and initial alteration rate by Soxhlet experiments) and also in terms of microstructure.

The industrial feasibility of the process has been demonstrated on a full-scale pilot facility (Cf. Figure 1), with surrogate solutions at the CEA Marcoule research center. The process was qualified by the following tests:

- Nominal, sensitivity, and transient-mode tests: ranges of glass compositions and parameter values were defined that ensure the production of glass with the same properties as the laboratory reference glass, and with acceptable volatility.
- Degraded-mode tests: management modes were defined to prevent any impact on the material properties after the return to nominal conditions.

The results obtained in terms of process control, material and volatility are discussed in the paper. A 3D thermohydraulic modeling of the furnace has been also developed in order to optimize the choice of operating parameters of experimental studies, optimize the internal design of the in-can furnace and improve the comprehension of glass elaboration with this process (Cf. Figure 2).