TY - JOUR A1 - Brekow, Gerhard A1 - Wüstenberg, Hermann A1 - Möhrle, Walter A1 - Schulz, Eduard T1 - Phased array concept for the ultrasonic inservice inspection of the spherical bottom of BWR-pressure vessels JF - Nuclear engineering and design N2 - The spherical bottom of BWR-pressure vessels contains holes for the nozzles of control rods and instrumentation. Up to now the detectable areas for the ultrasonic inspection are the accessible ligaments between the nozzles with an orientation parallel and transverse to the manipulator rails. Some licensing authorities demand an inspection technique capable of reliably detecting significant crack initiation in all critical areas near the cladding of the spherical inner surface. By order and in cooperation with the Hamburgische Electricitätswerke (HEW) we have developed a computer controlled equipment with two ultrasonic probes containing four linear arrays and a digitized A-scan storage for documentation and evaluation of inspection results. The manipulator guided probe movement in the paths between the nozzles of the spherical bottom is controlled by a computer program. This program determines for each array system and for each coupling position the beam angle as a function of the variable skewing angle to realize detection conditions suited to possible crack positions at the longitudinal, transverse and diagonal ligaments between the nozzles for control rods and instrumentation. KW - Phased array concept KW - Inservice inspection KW - Spherical bottom KW - Crack detection KW - Extension of the inspection volume PY - 1989 DO - https://doi.org/10.1016/0029-5493(89)90149-0 SN - 0029-5493 SN - 1872-759X VL - 112 SP - 105 EP - 114 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-24175 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -