Search

A demonstration-scale steam-assisted pyrolysis system was designed and tested for the treatment of the radioactive organic wastes which are difficult to incinerate such as halogenated organic compounds and phosphate esters. The steam-assisted pyrolysis system comprises a decontamination process for the gasification/separation of organic waste from nonvolatile radioactive nuclides by pyrolysis and a destruction process by submerged combustion. This two-step treatment system provides a high-volume reduction of waste and a very small amount of radioactive secondary waste. Tri-n-butyl phosphate/n-dodecane waste contaminated with uranium and simulated halogenated organic wastes stored in Japan Atomic Energy Agency were treated using the steam-assisted pyrolysis system. These wastes were reduced by 98 to 99.4% in weight during the treatment without any trouble using acidic compounds that are produced by the pyrolysis of wastes. Uranium was retained in the gasification chamber and the uranium concentration of se...

We present a reinforced ion current prediction model in alpha radioactivity measurement using ionized air transportation. Although our previous model explained the qualitative trend of the measured ion current values, the absolute values of the theoretical curves were about two times as large as the measured values. In order to accurately predict the measured values, we reinforced our model by considering columnar recombination and turbulent diffusion, which affects columnar recombination. Our new model explained the considerable ion loss in the early stage of ion diffusion and narrowed the gap between the theoretical and measured values. The model also predicted suppression of ion loss due to columnar recombination by spraying a high-speed air flow near a contaminated surface. This suppression was experimentally investigated and confirmed. In conclusion, we quantitatively clarified the theoretical relation between alpha radioactivity and ion current in laminar flow and turbulent pipe flow.