Pressure suppression system

A pressure suppression system 14 includes a containment vessel 24 surrounding a reactor pressure vessel 16 and defining a drywell 26 therein containing a non-condensable gas. An enclosed wetwell pool 28 is disposed inside the containment vessel 24, and an enclosed gravity driven cooling system (GDCS) pool 44 is disposed above the wetwell pool 28 in the containment vessel 24. The GDCS pool 44 includes a plenum 47 for receiving through an inlet 80 the non-condensable gas carried with steam from the drywell 26 following a loss-of-coolant accident (LOCA). A condenser 82 is disposed in the GDCS plenum 47 for condensing the steam channeled therein and to trap the non-condensable gas therein. A method of operation includes draining the GDCS pool 44 following the LOCA and channeling steam released into the drywell 26 following the LOCA into the GDCS plenum 47 for cooling along with the non-condensable gas carried therewith for trapping the gas therein.