Mossbauer study of the Boom clay, a geological formation for the storage of radioactive wastes in Belgium

摘要

In this work, Mossbauer spectroscopy has been used to characterize all the iron-containing phases in the Boom clay and to analyze their physico-chemical transformations induced by thermolysis and gamma radiolysis (60-Co). It is shown that sulfuric acid is produced by the oxidation of the pyrite present in the clay by the oxidizing species resulting from the gamma radiolysis of the interstitial water. The pH of the interstitial water decreases from 8.6 to 2.2 after complete oxidation of the pyrite, in agreement with the disappearance of this component as well as the siderite in the Mossbauer spectra.