New NDT manipulator is hot stuff!

New NDT manipulator is hot stuff!

New NDT manipulator is hot stuff!

Keywords Inspection, Welding

A unique new automated NDT inspection manipulator will speed up maintenance times at Sizewell A power station by allowing welding, heat treatment and ultrasonic testing to be carried out at the same time.

The manipulator, which can inspect welds continuously at temperatures of up to 170°C, with a minimal amount of insulation removed, was designed and manufactured for BNFL-Magnox Generation by Phoenix Inspection Systems Ltd. Three units have been produced so far, in a deal worth over £300,000 (see Plate 1).

Plate 1 Mike Rick of Phoenix carrying out final checks on the new manipulator

Engineers at Phoenix were faced with several design problems. Project engineer Dave Smith says: "Magnox wanted the manipulators for use whilst the boiler was being heat treated during the welding process, so the first consideration was the high temperature operation".

"The presence of vertical piping and horizontal stabilising beams on the boiler led to severe limitations of space, and we also had to take into account the electronically noisy environment in which it would be operating."

All parts in direct contact with the boiler have been selected to operate at up to 200°C and built-in heat breaks insulate these from other components. Motors, encoders and electrical boxes are air cooled.

The design was streamlined by the use of small but powerful DC motors and gearbox drives, and by careful positioning of parts. Only a 625mm wide strip of lagging around the welds needs to be removed ­ the circumferential track sits on top of the remaining lagging. Adjustments were built in to align the manipulator to the weld and to compensate for the uneven boiler surface.

The ultrasonics also posed major problems, own to the high temperatures, high electromagnetic background noise and prolonged duty cycle. With continuous scanning for up to 12 hours per day, seven days per week, transducers were designed specifically for the application and they underwent proving trials and third-party qualification.

The lightweight aluminium structure is easily handled and put into place within seconds. Probe pans can be replaced with the scanner in position.

Phoenix specialises in producing bespoke manipulators to the exact needs of the nuclear industry. Managing director Karl Quirk says: "Efficiency and ease of use were prime considerations in this job. Clever design can speed up maintenance and reduce downtime considerably, as this manipulator with its high temperature operation shows. It is certainly the first of its type we are aware of and we believe it to be unique within the industry".

For further information contact Phoenix Inspection Systems Ltd, 46 Melford Court, Hardwick Grange, Woolston, Warrington, Cheshire WA1 4RZ, UK. Tel: +44 (0)1925 826000; Fax: +44 (0)1925 838788; E-mail: utnde@phoenix.u-net.com