Chemical form analysis of reaction products in Cs-adsorption on stainless steel by means of HAXPES and SEM/EDX

In this study, for the understandings of Cesium (Cs) adsorption behavior on structure materials in severe accidents in a light water nuclear reactor, the chemical state of Cs and its distribution on the surface of SUS304 stainless steel (SS) with different Si concentrations was investigated by hard X-ray photoelectron spectroscopy (HAXPES) and scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDX). As a result, it was found that Cs is selectively adsorbed at the site where Si distributes with a high concentration. CsFeSiO4 is the dominant Cs products in case of low Si content, while Cs2Si2O5 and Cs2Si4O9 are formed in addition to CsFeSiO4 in case of high Si content. The chemical forms of the Cs compounds produced in the adsorption process on the SS surface have a close correlation with the concentration and chemical states of Si originally included in SS.