Patent Number: 041697588
Section: claims

1. In an apparatus for scanning the interior surfaces of a vertical cylindrical nuclear reactor vessel filled with collant and having an upper vessel flange and the top closure head removed to expose said flange, the combination comprising, a ring girder supported from the open end, a rotatable bridge spanning said girder, a carriage supported by and linearly movable in forward and reverse directions along said bridge, an axially movable vertical mast supported in said carriage depending into the reactor vessel, a boom supported by said mast extending at a right angle therefrom toward the cylindrical surface of the reactor vessel, and an articulated ultrasonic transducer inspection head carried by said boom axially aligned with and extending beyond the end of said boom remote from said mast. 2. Apparatus in accordance with claim 1 wherein said inspection head is rotatably supported in said boom. 3. Apparatus in accordance with claim 2 wherein said inspection head is pivotly joined to said boom. 4. Apparatus in accordance with claim 3 wherein said inspection head comprises a base pivotly joined to said boom, a housing rotatably mounted on said base, a shaft supported in and axially movable relative to said housing carrying a second base for supporting a first ultrasonic transducer axially aligned with said shaft. 5. Apparatus in accordance with claim 4 further including a second and a third ultrasonic transducer supported by said second base each independently movable relative to said first transducer. 6. Apparatus according to claim 5 further including means supported by said second base guiding said second and third transducers along an arcuate path when moving relative to said first transducer. 7. Apparatus according to claim 1 wherein said mast is hollow. 8. Apparatus according to claim 1 further including means producing a flow of a gas under pressure through said mast. 9. Apparatus according to claim 6 further including a contour control unit operatively connected to and automatically controlling the positioning of said bridge, carriage, mast and inspection head to thereby cause said inspection head to follow predetermined paths in scanning the interior surface of the reactor vessel. 10. Apparatus according to claim 1 further including a first television camera mounted on said inspection head for scanning the surface of the reactor vessel. 11. Apparatus according to claim 9 wherein said contour control unit includes means constraining the positioning of said bridge, carriage, mast and inspection head to within predetermined limits. 12. Apparatus according to claim 1 further including a second television camera pivotly mounted on said mast in axial alignment with the longitudinal axis of said boom.