Tight Fitting Garter Springs - MODAR
32nd Annual CNS Conference - 2011 June 05-08

Presented at:
32nd Annual CNS Conference
2011 June 05-08
Niagara Falls, Canada
Session Title:
Process Systems, Measurement, I & C, and Chemistry

Mitch King (AECL)
Dennis Kazimer (Bruce Power)


Annulus spacers are used in CANDUTM reactors to maintain the annular gap between two tubes - an inner pressure tube (PT) and the outer calandria tube (CT). Typically four annulus spacers are used in one fuel channel assembly, each at a specified axial position.

Bruce Unit 8 and many other CANDU units were constructed with tight-fitting garter springs (TFGS). The TFGS were not designed to be detected or relocated by the conventional tool, Spacer Location And Repositioning (SLAR) processes. 

Due to non-optimal ‘As Left’ construction locations for the Bruce Unit 8 TFGS, PT/CT contact has been predicted to occur well prior to its End of Life (EOL). Bruce Power entered a Project with AECL-CRL to design, manufacture & test and implement a new tooling system that would detect and reposition tight fitting annulus spacers.

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