Experimental studies for the estimation of soluble organic components leached from asphalt (6); Research of soluble organic components in the leaching test of asphalt under reducing condition

not registered ; Nishikawa, Yoshiaki*; Kagawa, Akio 

Organic TRU waste form (organic matrix and/or organic matter in waste) seems to be decomposed in the repository in long term by the reaction with water, radiation and by effect of microorganisms. Groundwater intruded into the repository dissolves soluble organic components as degradation products from the waste form. It is possible that complexation of transuranic elements with soluble organic component makes solubility higher and makes sorption coefficient of days and rocks lower. These phenomena may affect the performance assessment of the TRU waste repository. This paper reports the chemical degradation of asphalt as a material of organic TRU waste form by contacting water under reducing condition. The chemical degradation tests by contacting water in reducing condition were conducted in (1)asphalt +water +iron powder system (AH) (2)asphalt +calcium hydroxide +sodium nitrate water +ion powder system (ACNH) (3)asphalt +sodium hydroxide +water +iron powder system (AOH). The test result of TOC of leachant shows TOC does not increase by time in AH and ACNH case, but TOC of leachant increases in AOH case. In previous research, TOC in high alkaline (10M-NaOH) system in aerobic condition showed high value. Chemical degradation mechanism of asphalt seems to be mainly oxidative decomposition, but even under reducing condition it is possible that soluble organic components are formed by alkaline hydrolysis.