Patent Number: 063320118
Section: claims

1. A method of scanning a shroud weld in a nuclear reactor pressure vessel, the reactor pressure vessel comprising a shroud comprising an upper shroud section and a shroud head flange welded to one end of the upper shroud section, said method comprising the steps of: positioning a phased array ultrasonic probe on an upper surface of the shroud head flange;  emitting an ultrasonic beam from the ultrasonic probe;  electronically steering the ultrasonic beam to scan a weld joining the shroud head flange and the upper shroud section, the beam moving from an outer surface of the shroud head flange toward an inner surface of the shroud head flange; and  acquiring scan data over a length of the scan.  incrementally moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange;  emitting an ultrasonic beam from the ultrasonic probe;  electronically steering the ultrasonic sound beam to scan the weld joining the shroud head flange and the upper shroud section, the beam moving from an outer surface of the shroud head flange toward an inner surface of the shroud head flange; and  acquiring scan data over a length of the scan.  incrementally moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange;  emitting an ultrasonic beam from the ultrasonic probe;  electronically steering the ultrasonic beam to scan the weld joining the shroud head flange and the upper shroud section, the beam moving from an outer surface of the shroud head flange toward an inner surface of the shroud head flange; and  acquiring scan data over a length of the scan.  focusing the ultrasonic beam so that the focal point of the beam aligns with the upper fusion line of the weld and the outer surface of the shroud head flange; and  repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange from the outer surface of the shroud head flange to at least 0.5 inch past a weld fillet located at the intersection of the inner surface of the upper shroud section and the lower surface of the shroud head flange in discrete increments.  (a) positioning a phased array ultrasonic probe on an upper surface of the shroud head flange;  (b) emitting an ultrasonic beam from the ultrasonic probe;  (c) electronically steering the ultrasonic beam to scan the weld joining the shroud head flange and the upper shroud section, the beam moving from an outer surface of the shroud head flange toward an inner surface of the shroud head flange;  (d) acquiring scan data over a length of the scan;  (e) incrementally moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange;  (f) emitting an ultrasonic beam from the ultrasonic probe;  (g) electronically steering the ultrasonic beam to scan the weld joining the shroud head flange and the upper shroud section, the beam moving from an outer surface of the shroud head flange toward an inner surface of the shroud head flange;  (h) acquiring scan data over a length of the scan; and  (i) repeating said steps (e), (f), and (g) until the desired portion of the circumferential weld is scanned.  focusing the ultrasonic beam so that the focal point of the beam aligns with the upper fusion line of the weld and the outer surface of the shroud head flange; and  repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange from the outer surface of the shroud head flange to at least 0.5 inch past a weld fillet located at the intersection of the inner surface of the upper shroud section and the lower surface of the shroud head flange in discrete increments. 2. A method in accordance with claim 1 further comprising the steps of: 3. A method in accordance with claim 2 further comprising the step of repeating, until a desired portion of the circumferential weld is scanned, said steps of: 4. A method in accordance with claim 3 wherein incrementally moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange comprises the step of moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange in increments of about 0.05 inch to about 1.0 inch. 5. A method in accordance with claim 4 wherein incrementally moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange comprises the step of moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange in increments of about 0.05 inch to about 0.5 inch. 6. A method in accordance with claim 5 wherein incrementally moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange comprises the step of moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange in increments of about 0.05 inch to about 0.1 inch. 7. A method in accordance with claim 1 wherein emitting an ultrasonic beam from the ultrasonic probe comprises the step of focusing the ultrasonic beam so that the focal point of the beam aligns with an upper fusion line of the weld and a lower surface of the shroud head flange. 8. A method in accordance with claim 7 wherein electronically steering the ultrasonic beam to scan the weld joining the shroud head flange and the upper shroud section comprises the steps of: 9. A method in accordance with claim 8 wherein repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange comprises the step of repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange in increments of about 0.01 inch to about 0.5 inch. 10. A method in accordance with claim 9 wherein repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange comprises the step of repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange in increments of about 0.02 inch to about 0.2 inch. 11. A method in accordance with claim 10 wherein repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange comprises the step of repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange in increments of about 0.05 inch to about 0.1 inch. 12. A method of scanning a shroud weld in a nuclear reactor pressure vessel, the reactor pressure vessel comprising a shroud comprising an upper shroud section and a shroud head flange connected to the upper shroud section with a weld, said method comprising the steps of: 13. A method in accordance with claim 12 wherein emitting an ultrasonic beam from the ultrasonic probe comprises the step of focusing the ultrasonic beam so that the focal point of the beam aligns with an upper fusion line of the weld and a lower surface of the shroud head flange. 14. A method in accordance with claim 13 wherein electronically steering the ultrasonic beam to scan the weld joining the shroud head flange and the upper shroud section comprises the steps of: 15. A method in accordance with claim 14 wherein repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange comprises the step of repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange in increments of about 0.01 inch to about 0.5 inch. 16. A method in accordance with claim 15 wherein repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange comprises the step of repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange in increments of about 0.02 inch to about 0.2 inch. 17. A method in accordance with claim 16 wherein repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange comprises the step of repeatedly refocusing the beam so that the beam focal point moves along the upper fusion line of the weld and the lower surface of the shroud head flange in increments of about 0.05 inch to about 0.1 inch. 18. A method in accordance with claim 12 wherein incrementally moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange comprises the step of moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange in increments of about 0.05 inch to about 1.0 inch. 19. A method in accordance with claim 18 wherein incrementally moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange comprises the step of moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange in increments of about 0.05 inch to about 0.5 inch. 20. A method in accordance with claim 19 wherein incrementally moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange comprises the step of moving the phased array ultrasonic probe circumferentially along the upper surface of the shroud head flange in increments of about 0.05 inch to about 0.1 inch.