Reactor pressure vessel nozzle

A nozzle 24, 34 for joining a pool 18, 28 of water to a nuclear reactor pressure vessel 10 includes a tubular body 38 having a proximal end 42 joinable to the pressure vessel 10 and a distal end 44 joinable in flow communication with the pool. The body 38 includes a flow passage 46 therethrough having in serial flow communication a first port 48 at the distal end 44, a throat 50 spaced axially from the first port 48, a conical channel 52 extending axially from the throat 50, and a second port 54 at the proximal end 42 which is joinable in flow communication with the pressure vessel 10. The inner diameter of the flow passage 46 decreases from the first port 48 to the throat 50 and then increases along the conical channel 52 to the second port 54. In this way, the conical channel 52 acts as a diverging channel or diffuser in the forward flow direction from the first port 48 to the second port 54 for recovering pressure due to the flow restriction provided by the throat 50. In the backflow direction from the second port 54 to the first port 48, the conical channel 52 is a converging channel and with the abrupt increase in flow area from the throat 50 to the first port 48 collectively increase resistance to flow therethrough.