Abstract
The distributions of technetium among solid, liquid and gas phases in supercritical water reactions were investigated for the decomposition process of nonflammable plastic materials contaminated with technetium. In addition to supercritical water (SCW) methods with or without H2O2 which have been investigated extensively for decomposition method for the plastics, SCW with RuO2, developed by us, characteristic of reductive reaction was investigated for technetium distributions. The distributions of technetium were determined by using 95mTc tracer with or without its carrier 99Tc. The gases produced during the decomposition of the organic material contain no radioactivity under all conditions in this study. Also, technetium shows a tendency to transfer to solid phase but not to liquid phase in SCW with RuO2. These results indicate that this process is suggested as a predominant candidate for the treatment of nonflammable organic materials in low-level radioactive wastes (LLW).
