REMOTE EXTERIOR INSPECTION OF A REACTOR PRESSURE VESSEL

CURRENTLY, IN-SERVICE INSPECTION AND MONITORING OF FLAWS IN REACTOR PRESSURE VESSELS (RPVS) ARE PERFORMED FROM THE VESSEL INTERIOR ONLY DURING PLANT REFUELING OUTAGES. THIS PRACTICE IS UNDESIRABLE GIVEN THE HIGH RADIOLOGICAL EXPOSURES OF OPERATING PERSONNEL, SAFETY HAZARD TO CREWS WORKING OVER AN OPEN REACTOR, AND THE VERY COSTLY EXTENSION IN OUTAGE SCHEDULE WHICH CAN COST THE UTILITY ADDITIONAL TENS OF MILLIONS OF DOLLARS PER INSPECTION. INSPECTING RPV FLAWS FROM THE VESSEL'S EXTERIOR WAS DETERMINED TO BE IMPOSSIBLE DUE TO SEVERELY CONSTRICTED GEOMETRIES DEFINED BYSTRUCTURES AND COMPONENTS ADJACENT TO THE TYPICAL RPV. THISPROJECT WILL ASSESS THE FEASIBILITY OF, AND DEVELOP A PRELIMINARY CONCEPTUAL DESIGN FOR, A REMOTELY OPERATED ROBOTIC DEVICE THAT WILL CONDUCT NONDESTRUCTIVE EXAMINATION (NDE) OF RPV INDICATIONS OF DEFECTS FROM THE VESSEL EXTERIOR. THE INSPECTION SITES WILL BE ACCESSED VIA NARROW VERTICAL ANNULAR GAPS THAT EXIST BETWEEN THE VESSEL ITSELF AND INSULATION LAYERS/BIOLOGICAL SHIELDING SURROUNDING THE RPV. THE ROBOT WILL PERFORM MULTIPLE FUNCTIONS INCLUDING REMOTE VISUAL INSPECTION AND ULTRASONIC TESTING OR OTHER NDEPROCESSES.