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AEA commissions WELDTEST defect test assembly giant

Published on 24 January 2013

The biggest specimen ever taken on at Abington in the organizations history, was trundled into arc welding departments workshop. The job called for counter weighted crane, a high capacity trolley and a conveniently placed opening in the roof.

The 10t steam generator shell forging, which measured 3.6m in diameter, 1.5m deep and 100mm thickness, was intended for use in the proposed Hinckley B pressurized water reactor (PWR), but after government attitudes towards PWR`s changed in the late 1980`s the component was deemed surplus.

It was intended to be a validation specimen and by the time it left Abington it contained controlled flaws of a known size, distribution and orientation. The huge hoop like specimen was to be used to validate ultrasonic inspection operators, and their equipment, for the inspection of similar components.

TWI's task was to manufacture flaws and implant them in the specimen. It was a cross-departmental job; the Engineering Department made the flaws, the NDT Department sized them, and the Arc Welding Department installed them. The material was nuclear reactor steel A508 class 111, a low-alloy steel. The work was performed for the Inspection Validation Center of AEA Technology directly and ultimately for Nuclear Electric.

When asked how many flaws were installed within the specimen, project leader Richard Jones declined to tell. "The quantity, size, shape, orientation and distribution of the cracks are well kept secrets between our clients and our selves," said Jones. "We are experts at putting them in place. The NDT validation operators were simply told that there may be some flaws in this component. They were asked to find them and identify details."

Access scaffolding was erected around the specimen. "That allowed us to install two defects simultaneously top and bottom," said Jones. "The TIG process was used to install the flaws with four welders working on the job.'

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