A Feasibility Study on the Decontamination of Type 304 Stainless Steel by N2H4 Base Solution

摘要

Dissolution tests of Fe3O4 powders were performed in an acidic solution using a hydrazine base solution at a temperature range of 90-150 °C. The dissolved fraction of Fe3O4 was calculated from the analysis of iron ion concentration in solution using an atomic absorption spectrometer. The dissolution rate of Fe3O4 increased with [N2H4], time and temperature. The addition of copper ions to the hydrazine base solution greatly increased the Fe3O4 dissolution rate. This was explained by the complex formation between N2H4 and Cu ions and the reducing power of the hydrazine-Cu complex to the ferric ions of Fe3O4. The solution was also applied to the decontamination of Type 304 stainless steel specimen which was radioactively contaminated with a spinel type oxide layer. The contact dose rate of the specimen was measured before and after application of the solution to evaluate the decontamination performance. The contact dose rate was greatly decreased by the repetitive application of nitric acid-permanganate and the hydrazine base solution.