Reactor containment vessel vent system

A reactor containment vessel vent system that reduces pressure in a reactor containment vessel by releasing vent gas in the reactor containment vessel to the atmosphere, the reactor containment vessel vent system comprising:

• a vent line that forms a vent gas flow path through which the vent gas is discharged from the reactor containment vessel and released to the atmosphere;
• a noble gas filter provided at a downstream portion of the vent line, the noble gas filter allowing at least steam of the vent gas to pass through and not allowing radioactive noble gases of the vent gas to pass through;
• a return pipe that directly connects a portion of the vent line that is immediately upstream of the noble gas filter and the reactor containment vessel;
• an intermediate vessel provided on the return pipe and connected to the reactor containment vessel via the return pipe;
• a first check valve provided at a portion of the return pipe between the intermediate vessel and the reactor containment vessel;
• a relief valve provided at a portion of the return pipe that connects the portion of the vent line that is immediately upstream of the noble gas filter and the intermediate vessel;
• and
• a non-condensable gas collection system provided at the portion of the return pipe that connects the portion of the vent line that is immediately upstream of the noble gas filter and the intermediate vessel, between the relief valve and the portion of the vent line that is immediately upstream the noble gas filter;
• wherein the reactor containment vessel vent system is configured such that when a pressure of an immediate upstream portion of the noble gas filter exceeds a first set pressure, the radioactive noble gases that cannot permeate the noble gas filter flow into the intermediate vessel and are stored therein, and when a pressure in the intermediate vessel exceeds a pressure in the reactor containment vessel, the radioactive noble gases stored in the intermediate vessel flow into the reactor containment vessel via the first check valve provided on the return pipe;
• and
• wherein the intermediate vessel and the first check valve are passive components that operate without external power and facilitate the flow of the radioactive noble gases from the intermediate vessel into the reactor containment vessel via the first check valve even during a power outage.