Inspection of Bottom Mounted Instrumentation (BMI) J-Weld

Reactor Pressure Vessel (RPV) Bottom Mounted Instrumentation (BMI) primary nozzle ultrasonic (UT) inspections have been performed by AREVA for more than 15 years. EPRI demonstrations were performed in 2004 and an RSEM qualification was obtained in 2005, This UT inspection detects and characterizes cracks in the base metal of the penetration and its interface with the weld. A complementary Visual Examination of the weld or an Eddy Current examination may also be performed but these tests are understood to be marginal with a possibility to miss indications or to mistake inclusions or weld voids for in-service cracks and therefore could force an unnecessary repair. Difficulties associated with examination of this area include: • Unpredictable ultrasonic behaviour in the weld material; • Wavy and complex OD weld surface profile; • Restricted accessibility around the weld surface. AREVA’s Non Destructive Examination Technical Center (NETEC), has developed and/or evaluated several techniques to improve surface and volumetric inspection of this weld including: • A TOFD ultrasonic (UT) probe to detect and characterize cracks within the weld metal from the ID surface of the nozzle. • A flexible UT Phased Array probe to accommodate the wavy and complex weld surface, in partnership with CEA, • Reduced surface ET probes and flexible ET multi-coils (in partnership with CEA), for improved surface inspection, • Infrared Photo-Thermal Camera examination of the weld surface. This paper discusses the designs and performances of these specific probes and NDT techniques as applied to the BMI nozzles, J-welds, and other similar components.