Patent Number: 050842366
Section: claims

1. A nuclear reactor coolant pump for pumping reactor coolant fluid in a reactor coolant system, said pump comprising: (a) a casing defining an inlet nozzle for receiving a reactor coolant fluid, a converging spout outlet nozzle for discharging the reactor coolant fluid, and a passage interconnecting said inlet nozzle and said outlet nozzle through which the reactor coolant fluid can flow from said inlet nozzle to said outlet nozzle;  (b) a rotor extending axially through said casing and having an end disposed adjacent said passage defined by said casing; and  (c) an impeller mounted to said end of said rotor and disposed in communication with said passage, said impeller being rotatable with said rotor about an axis, said impeller being axially offset from said outlet nozzle for drawing fluid into said casing through said inlet nozzle and discharging fluid from said casing tangentially through said converging spout outlet nozzle after flow through said passage;  (d) said converging spout outlet nozzle being composed of first and second wall portions defined above and below an imaginary plane extending generally parallel to said rotation axis of said impeller, said first wall portion extending substantially tangentially to said casing and having a substantially semi-cylindrical shape, said second wall portion having a combined substantially semi-elliptical and semi-conical shape. 2. The coolant pump as recited in claim 1, wherein an exit opening of said converging spout outlet nozzle has a substantially circular shape. 3. The coolant pump as recited in claim 1, wherein said semi-conical shape of said second wall portion defines a cone angle of less than approximately thirty degrees. 4. The coolant pump as recited in claim 1, wherein said semi-conical shape of said second wall portion defines a cone angle of approximately twenty-five degrees.