The Economiser Penetration Scanning Mechanism or EPSOM scanner was developed for ultrasonic inspection of a number of circumferential welds on economiser penetrations on the Advanced Gas cooled Reactor (AGR) power station – a design used in the UK. This weld was located approximately 5.2m from the edge of a shutter tube.
The manipulator fits between the inner and outer pipes of the economiser which limits the radial thickness of the manipulator to 40mm. The inspection is carried out by scanning up to eight probes over the external surface of the inner pipe.
Access to the entrance of the economisers is very restricted, both by accessories attached to the economiser and by nearby pipes and fittings. The pipe being scanned increases in diameter soon after exiting the wall and this, together with the other obstructions, limits the maximum straight length which can be inserted. Items which are longer than the maximum permissible need to either bend, such as the insertion tubes, or be hinged like the spacer bars to enable them to negotiate the access.