Primary containment vessel with outer pool

Abstract

A primary containment vessel, comprising a reactor pressure vessel in which a core is accommodated, a dry-well volume covering the upper portion of the reactor pressure vessel, a suppression chamber provided with a suppression pool surrounding an intermediate portion of the reactor pressure vessel, has a plurality of vent tubes establishing a connection between the dry-well volume and the suppression pool and an annular baffle plate disposed in the suppression pool along the side wall of the suppression chamber, having its top end positioned at a height between a free surface of the suppression pool and an outlet of the vent tube opened in the suppression pool and its lower end positioned at a height between the outlet and the bottom of the suppression pool. If a loss of coolant accident occurs, hot steam discharged into the dry-well volume is discharged into the suppression pool through the vent tube so as to heat water on the inside of the baffle plate. The water head difference generated by the water temperature difference between the inside and the outside portions of the baffle plate causes a vertical convection passing through the baffle plate to be created. Therefore, the heat accumulating characteristics of pool water and the heat radiation performance of the containment vessel are improved, allowing the size of the containment vessel to be reduced.