FORMATION OF PRIMARY RADIOCOLLOIDS IN LEACHING OF SODIUM-ALUMOPHOSPHATE GLASS MATRIX OF RADIOACTIVE WASTE

A.M. Pervukhina

Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, Russian Academy of Sciences, Staromonetnyi per. 35, Moscow, 119017 Russia. E-mail: Pervukhinaa@hotmail.com

We considered an effect of provisional storage of sodium-alumophosphate glass matrix of high-level radioactive waste (HLW) on its resistance to the groundwater influence after the final disposal in a geological repository. A transformation of the Na-Al-P-glass with HLW simulators in a dry steam at elevated temperatures is examined. Stable isotopes of Cs, Sr, and U as well as Ce and Nd, as geochemical analogues of actinides (Pu, Am, Cm), were doped to the glass as radionuclide simulators. Ageing of the Na-Al-P-glass in an autoclave for 24 hours at the temperature of 300oC and humidity of 66% leads to its devitrification. This causes a substantial deterioration of leaching resistance of the matrix. Predominant part of Sr, U and REE-simulators of actinides in the leaching solution is in colloidal form.

Key words: radioactive wastes, underground repository, waste form, glass, crystallization, leaching, colloidal form of transport.

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