A nuclear power plant has a reactor pressure vessel (1), a primary containment vessel (3) and a passive pressure suppression pool cooling system. The reactor pressure vessel (1) is installed in the primary containment vessel (3). A pressure suppression pool (7) filled with cooling water is formed in a lower portion of the primary containment vessel (3). The passive pressure suppression pool cooling system is provided with a steam condensing pool (5) in which cooling water is filled, disposed outside the primary containment vessel (3), a steam condenser (4) disposed in the steam condensing pool (5), a steam supply pipe (2) connecting the reactor pressure vessel (1) to the steam condenser (4), and a condensed water discharge pipe (6) connected to the steam condenser (4) for discharging condensed water generated in the steam condenser (4). Another end portion of the condensed water discharge pipe (6) is disposed in the pressure suppression pool (7).