Detritiation Behavior of HTO in a Epoxy Paint

Abstract

Transport properties of tritiated water vapor (HTO) in the epoxy paint such as adsorption, desorption, diffusion and dissolution has been evaluated by investigating the HTO exposure and removal behavior from the epoxy paint in order to generate a data base on tritium behavior in tritium-confinement facilities such as the Hot Cell and the tritium plant building in ITER. Two types of experiments were carried out; one was the HTO exposure to the epoxy paint, and the other was the detritiation curves from the epoxy paint after the HTO exposure. Stainless steel vessel chambers with the epoxy painted inside surfaces were first exposed to an air flow containing HTO vapor (740 Bq/cm3) for 1 week, 2 weeks and 2 months. After these exposures, detritiation of these chambers with an air flow was carried out. It was found that the interaction between the surface of the epoxy paint and the HTO such as adsorption and desorption is reached the steady state under these conditions. Based on experimental detritiation curves, the transport properties were evaluated using the tritium transport analysis code, TMAP. The trapping effect is the strong bonds between the HTO and the epoxy such as the chemical bonds, which is represented by trapped HTO in this analysis. Although diffusivity and solubility of HTO in epoxy paints almost agreed with the previous investigations, trapping like effect should be considered to explain observed detritiation behavior.