Recycling pump in nuclear reactors

Purpose: To surely prevent reactor water in a pressure vessel from discharging through ruptured portions even if ruptures should occur in the primary coolant circuits. Constitution: A check valve is disposed to the coolant outlet of primary coolant circuit for preventing the backward flow of the coolants. Further, an ON-OFF valve is disposed to the coolant inlet for inhibiting the entrance of coolants. The ON-OFF valve is closed if the coolant pressure in the primary coolant circuit is lowered to less than a required pressure. Thus, reactor water and motor cooling water flowing to the motor section of a pump upon occurrence rupture accident in primary coolant circuit are confined within the motor section and kept from flowing externally. (Ikeda, J.)