Patent Number: 043308651
Section: summary

BACKGROUND OF THE INVENTION This invention relates to non destructive test apparatus and provides a free roving vehicle for carrying inspection instrumentation over a remote surface. A vehicle according to the invention finds application in the inspection of a primary vessel of a construction of liquid metal cooled nuclear reactor of the pool kind. Such a nuclear reactor construction comprises a nuclear fuel assembly submerged in a pool of liquid metal coolant contained in the primary vessel which is housed in a concrete containment vault. In use the primary vessel is subject to irradiation and to severe thermal stress so that periodic inspection of the vessel is required to ensure its continued integrity. Inspection of the primary vessel is difficult because it must be carried out on its external surface by remotely operated apparatus. SUMMARY OF THE INVENTION According to the invention a vehicle for carrying non destructive test instrumentation over a remote surface comprises a bridge structure having a plurality of support pads pivotally mounted thereon, each support pad having suction means for adhering the vehicle to an inclined or inverted surface and fluid thrust means arranged in opposition to the suction means to facilitate lateral sliding displacement of the vehicle and a resiliently flexible tubular tie member for suspending the bridge structure and conducting fluid supplies thereto. According to another aspect of the invention a method of inspecting the primary vessel of a liquid metal cooled nuclear reactor of the pool kind housed in a closed vault comprises mounting inspection instrumentation including a television camera on a vehicle, suspending the vehicle and instrumentation in an interspace bounded by the primary vessel and the vault, adhering the vehicle to the vessel by suction means, vertically displacing the vehicle in step wise manner and intermittently anchoring the vehicle to the surface of the vessel by the suction means prior to inspection of the surrounding terrain.