GENTILLY-2 Moderator Heat Exchanger Repair

Abstract

At the time of an unscheduled outage for a problem with the fuelling machine, an operator noted a sound coming from the inlet moderator heat exchanger 3211-HX1. The noise was reported as a loose object knocking around between the tubesheet and the inlet piping. Upon separating the tubesheet from the Heat Exchanger, the tubesheet overlay and tubes extensions were found severely damaged. The repair work would be required to be performed insitu in a highly contaminated environment during end of the year where obtaining manpower resources were difficult. The team work between Hydro-Quebec and Babcock & Wilcox Canada Nuclear Services and use of non-conventional tooling was a big part of the success for this project. The repair started on December 21st, 2007 and the vessel was turned over to HQ on January 24, 2008.