Reactor container

The opening of a pressure suppression bent tube on the side of a dry well, which connects a wet well and a dry well in a reactor container, is disposed near the height of a main steam pipe. Further, the exhaust port of a vacuum destruction valve on the side of the dry well, which connects the wet well and the dry well, is disposed at the lower portion of the dry well. Incondensible gases present around the main steam pipe upon occurrence of a main steam pipe rupture accident are transferred to the wet well passing through the pressure suppression vent tube having an opening near the height of the main steam pipe, together with steams flown to the dry well passing through the ruptured opening. Further, when the vacuum destruction valve is opened, the incondensible gases in the wet well are released to the lower portion of the dry well. This can suppress the incondensible gases from flowing to an isolation condenser, thereby enabling to conduct efficient after-heat removal. (I.N.)