The water of Suppression pool at severe accident has become a hot, high chloride ion concentration and strong alkaline because of exhaust of the reactor heat, the melted cable, and pH controller. The equipment using the water has wetted part made stainless, therefore there is a possibility that SCC because of chloride ion occurs this wetted part. However, alkaline environment may reduce a possibility the SCC although poor knowledge. As such we examined the effect of structural material in a hot, high chloride ion concentration, and strong alkaline environment. In paper, we introduce about the result of the examination.