Nondestructive inspection equipment and technologies for reactor vessel head penetration degradation management

Several pressurized water reactors have experienced primary coolant leaks as a result of cracking in the tubes and J-Groove welds in reactor vessel head penetrations. The cracks have been attributed to primary water stress corrosion cracking (PWSCC) of the Alloy-600 nozzle material and Alloy-182 weld material. Westinghouse has been actively involved in investigating the root cause, establishing a safety position, and developing inspection and repair strategies to address the reactor vessel head penetration cracking issue. Westinghouse and our partner, R. Brooks Associates, have available remote tooling and inspection technology to perform 'under the insulation' visual inspections to identify evidence of leakage in the form of boric acid deposits. Westinghouse resources from Germany, Sweden and the United States have cooperatively developed equipment and nondestructive technology for providing 'under the head' eddy current and ultrasonic inspection techniques for identification and characterization of degradation that might exist in the penetration tube OD and ID surfaces and the J-Groove welds. Some of these developments represent significant advancements to technologies and equipment developed originally ten years ago. Since 1992, Westinghouse has performed over 140 reactor vessel head penetration nondestructive examinations of various scopes at pressurized water reactors all over the world. Westinghouse also has available repair methods to address the known or anticipated cracking scenarios. Remote repair capability is available for electron discharge machining, welding, and dye-penetrant testing. This tooling is delivered using the same manipulator as that for the under the head nondestructive examinations. This paper will provide details of the inspection capabilities that Westinghouse has available to support our comprehensive Reactor Vessel Head Penetration Degradation Management Program