About three years ago, Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI) completed design and development of a new and unique type of scanner for conducting ID examinations on BWR shell welds. The AIRIS 21 inspection system was developed by IHI in response to the increased demand for inspection of BWR vessel seam welds from the ID of the vessel. This system represented a significant advance over existing systems in terms of its dramatically reduced size, weight, and complexity. Recently, IHI and IHI Southwest Technologies (ISwT) have been working together to develop additional high performance UT capabilities for a variety of BWR in-vessel applications.

System Operation
The AIRIS 21 scanner is small [550 mm (22 in. ) wide, 600 mm (24 in. ) tall, and 55 mm (2 in. ) thick] and weighs only 13.6 kg (30 lbs. ). A flexible skirt makes contact with the wall and two thrusters create a partial vacuum between the device and the vessel wall, allowing the drive wheels to make contact with the vessel surface. Two independent drive wheels (travel motion) and one free caster wheel allow free maneuvering around the vessel surface. Independent encoder wheels provide coordinated tracking of device position regardless of motion direction. A linear drive (scanner motion) provides search unit module movement perpendicular to the traveling motion of the device.

System Upgrades
The AIRIS 21 scanner was originally designed by IHI to employ standard American Society of Mechanical Engineers (ASME) Code techniques. ISwT has integrated its Performance Demonstration Initiative (PDI)-qualified UT detection and sizing techniques with the scanner for vessel shell weld examinations. ISwT has used this scanner to perform inspections on two BWR vessels since its introduction in 1997.

IHI has developed additional scanners based on the AIRIS concept, one for core shroud examinations from the outside of the shroud and another that can access the inside of the core shroud. ISwT is in the process of qualifying personnel and developing procedures for core shroud examinations using these scanners.

IHI has also utilized the AIRIS concept for positioning of various visual equipment, cleaning and grinding equipment, and laser welding equipment to the inside of the vessel.

Summary
The AIRIS underwater scanner concept has been proven for application of reactor vessel weld inspection. IHI and ISwT are continuing to use this concept for improvement of additional in-vessel inspection and maintenance applications.