Patent ID: 7136449

Claim:
A nuclear reactor plant which includes a helium cooled nuclear reactor positioned in a cavity defined by a shell; and a closed loop liquid cooling system which includes at least one coolant chamber defined by a wall having ends which are sealed off respectively by a top and a bottom and positioned in the cavity adjacent to the nuclear reactor; a pump having an inlet side and an outlet side; a coolant inlet pipe which is connected in flow communication with the outlet side of the pump and which enters the coolant chamber through the top and extends downwardly through the coolant chamber to a discharge end positioned within the coolant chamber; an outlet leading from the coolant chamber which is connected in flow communication with the inlet side of the pump; and at least one anti-siphon bleed opening provided in that portion of the coolant inlet pipe positioned in the coolant chamber at a position spaced from the discharge end whereby the coolant inlet pipe and the coolant chamber are connected or connectable in flow communication.