Adjuster Absorber Rods Return To Service At Plngs

The original CANDU® 600 design utilizes adjuster absorber rods to flatten the flux shape in the reactor core optimize power output, compensate for fuel burnup, provide excess reactivity to overcome ¹³⁵Xe buildup following a power reduction, and allow for reactivity shim. At Point Lepreau Nuclear Generating Station (PLNGS) in 1999, adjuster absorber banks 6 and 7 were locked in the reactor core and removed from service. Later in 2019 adjuster absorber banks 1 through 5 were placed on manual. Since then, a significant program was put in place to restore adjuster banks 1 through 6 to service, which was successfully completed in October 2023. Adjuster absorber bank 7 remains locked in-core. This paper summarizes the rationale for removing the PLNGS adjuster absorbers from service, the effort required for their restoration, applicable lessons learned, and next steps.