Retention of Sn(IV) and Pu(IV) onto four argillites from the Callovo–Oxfordian level at Bure (France) from eight equilibrated sedimentary waters

Abstract

SummaryWithin the framework of studies concerning the migration of radionuclides in a potential nuclear waste disposal host rock, the retention properties of clayey materials towards Sn(IV) and Pu(IV) are approached. Chemical sorption is quantified with the partitioning coefficientKd, whose value is dependent on the physico-chemical conditions. Four argillites are selected from three different deep boreholes at Bure to characterise the retention of Pu(IV) and Sn(IV) in eight waters close to the interstitial solution. No differences in major mineralogical composition distinguished these argillite samples. However, significant differences in retention properties of these argillites in the same water towards Sn, could be attributed to minor phases not identified by DRX. Retention of Sn or Pu is not sensitive to weak physico-chemical conditions variations.Ehconditions were imposed in the stability domain of Pu(IV). An auxiliary redox couple was tested and its impact on the results is briefly discussed. Sorption reversibility is verified for Sn(IV) and Pu(IV).