Nuclear reactor coolant transport system

An arrangement for transporting reactor coolant fluid in a nuclear reactor system comprising:

• a sealed reactor vessel;
• a primary variable speed pump having an inlet and outlet and being of a type having a motor disposed above a coolant reservoir and an elongated shaft connecting said motor to an impeller, said impeller receiving coolant from said inlet and discharging coolant to said outlet, said impeller also being in fluid communication with said reservoir;
• a heat exchanger;
• piping for directing coolant between said vessel, pump and heat exchanger in a recirculating loop including upstream piping directly connecting said pump inlet and the one of said vessel and heat exchanger upstream of said pump;
• means for controlling the pressure of coolant entering said pump inlet including a bypass conduit directing a portion of said coolant exiting said pump to said upstream piping, said bypass conduit directly connecting said pump outlet to said upstream piping, said bypass conduit discharging said portion into said upstream piping through a plurality of nozzles, said nozzles disposed about the outer periphery of said upstream piping and directed such that said portion is injected into said piping from the outer periphery of said piping into said piping generally in the direction of coolant flowing in said piping.