X-ray Absorption Fine Structure Studies of Speciation of Technetium in Borosilicate Glasses

摘要

A series of glass samples were prepared analogously to high level waste glass using either glass frit or glass precursors combined with a high level waste surrogate containing NaTcO_4. Three different technetium species were observed in these glasses depending upon the synthesis conditions. If the glasses were prepared by reducing NaTcO_4 to TcO_2·2H_2O with hydrazine or if a large amount of organic material was present, inclusions of TcO_2 were observed. If no organic material was present, technetium was incorporated as TcO_4~-.If only a small amount of organic material was present, isolated Tc(IV) sites were observed in the glass. The relative technetium retention of these glasses was estimated from the Tc K-edge height, and had no correlation with the oxidation state of the technetium. Pertechnetate was well retained in these glasses.