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Some Aspects of Leaching Mechanisms of Ions Incorporated in Cement or Polymer

Objective

The present work aims at further elucidation of some mechanisms which govern the elution, by water, of some important ions from solids simulating solidified low or medium level radioactive wastes.
The distribution of Sr ion in the cement matrix after a long period of leaching as well as the physicochemical state of water within the pores in this matrix will be investigated.
In the work concerning polymers the experimental study of the sorption and diffusion behaviour of a model polymer-NaCl-H2O system will permit the more detailed application and testing of the theoretical approach describing the elution of salts of both high and low solubility embedded in hydrophobic matrices, taking into account the concurrent uptake of water.

Work programme:

Experiments on distribution of Sr in different cement specimens containing inactive Sr in the form of SrSO4 and Sr-90 in the form of Sr(NO3)2.
Thermogravimetric and differential scanning calorimetry measurements and porosimetry measurements to assess the physicochemical state of water.
Sorption and diffusion experiments with NaCl in polymer films and parallel measurements of the rate of water sorption.
Equilibrium water uptake by polymer films at different relative humidities and salt content.
Study of ion transport using Na-22 and Cl-36 tracers.
Modelling and interpretation of results.

Coordinator

NATIONAL CENTRE FOR SCIENTIFIC RESEARCH 'DEMOKRITOS'
Address
Terma Patriarchou Grigoriou
15310 Athens
Greece