Steam-Assisted Pyrolysis System for Decontamination and Volume Reduction of Radioactive Organic Waste

Abstract

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 secondary waste water was very low, thus permitting the discharge of neutralized waste water to the environment.