Radiometric Estimation of Porosity in Oxide Films

Abstract

Sorption of ⁶⁰Co and ¹³⁷Cs on steels as influenced by cations and anions of various electrolytes was studied. It was shown that the larger the cation charge, the stronger was suppressed the sorption. For trivalent cations, the degree of suppression of radionuclide sorption is comparable with that exhibited by corrosion inhibitors. The only exception is abnormally high sorption of ⁶⁰Co on pearlite steels in Ni(NO₃)₂ solutions. Based on the results of the experiments, procedures for determining the bulk and through porosities of coatings were developed. The bulk porosity is estimated from the residual radioactivity after keeping the sample with a coating in a radioactive solution with Cr(NO₃)₃ + K₂Cr₂O₇ addition. The through porosity is estimated by treating the samples (with and without the coating) with a nickel(II) nitrate solution, followed by measuring the residual radioactivity and calculating the porosity by appropriate formulas.