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.
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