[en] Risley Nuclear Laboratories have developed and applied automated wide-beam pulse-echo and time-of-flight techniques with synthetic aperture processing for sizing defects in clad thick-section weldments and nozzle corner regions. These techniques were amongst those used in the four test plate inspections making up the UKAEA defect detection trials. A critical appraisal is given of the sizing procedures adopted by RNL in these inspections. Several factors influencing sizing accuracy are discussed and results from particular defects are highlighted. The time-of-flight technique with colour graphics data display is shown to be highly effective in imaging near-vertical buried defects and underclad defects of height greater than 5 mm. Early characterization of any identified defect from its ultrasonic response under pulse-echo inspection is seen as a desirable aid to the selection of an appropriate advanced sizing technique for buried defects. (author)