Retention of aqueous $^{226}$Ra fluxes from a subaqueous mill tailings disposal at the Bois Noirs Site (Loire, France)

Christelle Courbet (1) , Caroline Simonucci (1) , Alexandre Dauzères (1) , Sylvain Bassot (2) , Arnaud Mangeret , Jean-Michel Matray (1)

1 IRSN/PRP-DGE/SRTG/LETIS - Laboratoire d'Etude et de recherche sur les Transferts et les Installations dans les Sols
2 IRSN/PRP-DGE/SRTG/LAME - Laboratoire d'Analyses et des Moyens Expérimentaux

This study focuses on a subaqueous mill tailings disposal s ite located in France (Bois Noirs) where 1.3 million tons of uranium mill sludge (fine tailings fraction < 50 μm) have been disposed since the 60’s in a man-made pond below 4 meters of water maintained artificially by a rock-fill dam. A significant attenuation of aqueous $^{226}$Ra activity is observed in ground waters. This paper presents the preliminary modeling work performed for evaluating the role of water-rock interactions on aqueous $^{226}$Ra attenuation through the dam. This modeling attempt, assuming thermodynamic equilibrium, aims at checking the hydrochemical conceptual model developed in a previous study, in which Ra retention through the dam was assumed to most likely result from sorption onto metallic oxide-hydroxides. A 2D coupled reactive transport model was conceived to test this hypothesis over time and identify the measurements required to verify its consistency over the long term

Mots clés: radium; mill tailings; natural attenuation; water coverdam; retention modeling

Domaines: Chimie

Christelle Courbet, Caroline Simonucci, Alexandre Dauzères, Sylvain Bassot, Arnaud Mangeret, et al.. Retention of aqueous $^{226}$Ra fluxes from a subaqueous mill tailings disposal at the Bois Noirs Site (Loire, France). Procedia Earth and Planetary Science, 2013, 7, pp.183-186. ⟨10.1016/j.proeps.2013.03.108⟩. ⟨hal-03784312⟩