Ontario Power Generation reports that an extensive 16-year overhaul of the second-largest hydroelectric station in the province is under way to help secure additional decades of reliable, clean power.

The project to overhaul all 16 units at the 1,045 MW R.H. Saunders Generating Station on the St. Lawrence River kicked off in January, with the first unit, G9, now fully disassembled. The G9 refurbishment is set to be completed by early 2024, with overhauls on the rest of the hydro units occurring each subsequent year, to wrap up the project by around 2039.

Each unit overhaul will involve replacing the 62-tonne turbine runner, which includes the steel blades that help convert rushing water into electricity. The runners will be replaced with newer, more efficient designs that will require less water to generate power. Another priority will be replacing the round throat ring liner with a more adjustable design to deal with a unique, concrete growth inside the units that can deform the liners over time. The phenomenon, called Alkali Aggregate Reactivity, involves a chemical reaction in concrete when certain aggregates are used. Over time, swelling from this reaction can cause expansive pressure that could interfere with movement of the turbines.

Each overhaul will also involve installing new servo motors and thrust bearings; setting up new electrical systems; and completing machining, welding and painting of the various generator and turbine components.