Lessons Learned from the NRU Vessel Leak Repair and Return to Service Projects
9th International Conference on CANDU® Maintenance - 2011 December 04-06

Presented at:
9th International Conference on CANDU® Maintenance
2011 December 04-06
Toronto, Canada
Session Title:
Learning from OPEX Session A3

Phyllis Heeney (AECL Nuclear Laboratories)
Jennifer Turcotte (Atomic Energy of Canada Limited)


In May 2009 the NRU reactor was shut down due to a small leak detected from the reactor vessel into the annulus surrounding the reactor.  What ensued was a challenging, yet successful, 15 month long Repair and Return to Service Outage.

This Repair and Return to Service Outage presented many first-of-a-kind challenges that provide learning opportunities which have been incorporated into subsequent planned outages.   These lessons learned are invaluable tools to be used in the planning and execution of future outages.

Following the repair of the NRU vessel, AECL was required to conduct annual inspections of the vessel wall.  These inspections require an Extended Outage (up to 4 weeks in length).  A planned Extended Outage was conducted in May/June 2011 and provided an opportunity to implement some of the lessons learned during the Repair and Return to Service Outage.

Lessons learned from that Extended Outage have been incorporated in the subsequent monthly maintenance outages, with lessons learned sessions being held after each outage to ensure that the execution of outages is constantly improving.

This paper discusses

  • The various lessons learned during the:
      • 2009/2010 Repair and Return to Service Outage;
      • 2011 Planned Extended Outage;
      • 2011 Monthly Maintenance Outages
      • How the Lessons Learned are being incorporated in subsequent outages; and

The path forward for future outage improvements.

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