Patent Number: 050826190
Section: abstract

A nuclear system of the type which includes a containment wherein a nuclear reactor pressure vessel is located has a suppression pool to which steam can be vented so that it will condense and reduce the pressure in the pressure vessel upon the happening of an accident such as loss of reactor coolant or a steam pipe failure. Steam also can be vented directly to the containment space to further reduce pressure in the reactor. When reactor pressure is lowered to a certain pressure value, a gravity supply of water from an elevated pool of water will have a sufficient head to flow against the pressure in the reactor and into the reactor to submerge the fuel rods in the reactor. One or more isolation condensers are submerged in a large supply of water this supply being elevated some distance above the pressure vessel. At least one isolation condenser has inlet thereto communicated to an open entry conduit disposed in the containment. Steam in the containment space can enter the isolation condenser to be cooled at any time an accident occurs and steam is vented into the containment. The condensing of steam in the condenser boils water in the large supply but since the large water supply is open to atmosphere the boil-off is vented. Condensate resulting from cooling occurring in the isolation condenser is returned to the suppression pool and non-condensable gases present in the steam being condensed are separated from the condensate and vented to the suppression pool.