Glass - Back to the Future!



Presenting Author:
Nolwenn Chouard
<nolwenn.chouard@areva.com>

article posted 3 Mar 2016


Dr Nolwenn Chouard works for AREVA as a R&D project manager on nuclear waste vitrification. Before that, she has done her PhD on glass formulation with the CEA of Marcoule.






Challenging elements incorporation in nuclear borosilicate glass:
the French formulation experience

Nolwenn Chouarda*, Olivier Pinetb

Vitrification is the internationally recognized method for immobilizing radioactive liquid waste streams in preparation for long-term storage. The amorphous and robust atomic network of alkali borosilicate glass is well suited to accommodate a wide range of constituent elements and compositions while retaining good chemical durability and stability under radiation. Nevertheless, there are certain components of waste streams which are not easily incorporated in borosilicate glass. For example, noble metals present a very low solubility in borosilicate glass and strongly affect the electrical and rheological properties of the glass melt. Besides, they are well known for acting as nucleating agents. Rare-earths and molybdenum as for them present a low solubility in borosilicate glass and can induce crystallization and/or liquid-liquid phase separation that can affect long term behaviour of glasses. Finally, halogen elements incorporation is also particularly challenging because of their high volatility. Although they generally represent only a very small fraction of waste solutions, halogens alone are projected to account for most of the cumulative long-term environmental radiation dosage associated with geological storage of nuclear waste. The understanding of their behavior in glass is thus of major importance.

The aim of this paper is to present the nuclear glass formulation French experience with the methodology developed for designing optimized industrial glass formulation. Besides, some examples of current and specific solubility, structural and long term behaviour studies will also be presented.

Institutions:

a AREVA NC, 1 Place Jean Millier, 92084 Paris-La Défense, France

b CEA/DEN/DTCD/SECM/LDMC Marcoule, BP 17171, 30207 Bagnols-sur-Cèze, France