US Patent 6856662 Remote examination of reactor nozzle J-groove welds

A combined laser and infra red sensing camera is located beneath the reactor head in the vicinity of the closure head tube welds by manipulating known robotic device handling the laser which is used to heat a line along the surface thereby generating a thermal wave that propagates over the one to two square inch test area where the increased thermal resistance of cracks and anomalies makes the surface temperature profile gradient greater at a crack or anomaly. An IR camera captures the test area image of interest as the thermal wave propagates across the target inspection area and the image is processed and enhanced to show cracks and other anomalies as a sharp drop in the thermal scan at the point of the crack using known Photo Thermal NDE technology to convert the scan into a pictorial representation of the scanned surface clearly showing any cracks therein. This process is repeated sequentially until the entire circumference of the weld is scanned.