Nuclear reactor

Purpose: To facilitate operator's access and loading and unloading of various equipments and materials to and from the bottom of a pressure vessel of a nuclear power plant to thereby improve the workability, as well as provide and excellent design for the earthquake proof structure. Constitution: A building for containing a containment shell is constructed on a power plant building mat. A suppression chamber is provided to the lower outside of the dry well in the containment shell above the building mat and supported on supports. Spaces are formed between the suppression chamber and the mat in which an eccs pump is installed. A sufficient water head between the water levels of cooling pump and the suppression pool can thus be maintained, digging work for the building mat can be saved and the use of a horizontal type cooling pump is enabled. Installation and maintenance for the pump can thus be facilitated, recess for placing the building mat can be saved and the earthquake proofness can be improved. (Horiuchi, T.)