Darlington Retube & Feeder Replacement Project

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How we made the difference
What we built
Why does it matter?

How we made the difference
What we built
Why does it matter?

Markets

Nuclear
Location

Ontario, Canada
Client

Ontario Power Generation

The Darlington nuclear station is Canada’s second largest nuclear facility by total energy output.

It has provided 20% of Ontario’s electricity since the early 1990s. But by 2016 its four reactors needed refurbishing and modernizing, to keep them operating safely and efficiently for another three decades.

The nuclear industry has a long history in Canada, with the CANDU (Canadian Deuterium Uranium) reactors setting a high standard in design, innovation and sustainability. Modernizing Darlington’s four CANDU reactors would ensure that Ontario could continue to benefit from safe and reliable baseload for decades to come. The refurbishment remains Canada’s largest clean energy initiative to date.

$ 2.75 bn

contract

480

fuel channels and components replaced

1920

multi-ton heavy lifts required

days reduction to outage schedule

This tooling success is just another example of our long history of innovation, including the ability of CANDU reactors to use several alternative fuels

How we made the difference

In 2016, we entered into a joint venture with Aecon Group for a $2.75 billion contract to carry out the execution phase of the Darlington Retube and Feeder Replacement scope of work.

Before commencing on-site work, we created a detailed execution plan that identified the materials, parts and steps needed to successfully execute such a complex project. We also had to organize how each of the four CANDU reactors could be taken out of service, one at a time, to replace their fuel channels. These outages can be costly – at a tune of up to $1m per day – which presents a strong incentive to reduce the time needed. But in a Canadian nuclear sector globally recognized for its best-in-class technology and ongoing innovation, high-quality work and safety standards were essential deliverables too.

What we built

Each CANDU reactor contains 480 fuel channels. Removing and replacing these fuel channels and their components typically requires 1,920 multi-tonne heavy lifts.

Each one cost time and money. Through discussions and preliminary assessments using historical data, our team was able to successfully identify and develop a new tooling system that could remove calandria tubes and pressure tubes in one extraction, instead of two separate ones. Consequently, each 480-channel reactor could be replaced in 960 heavy lifts, instead of 1,920.

This innovation dramatically shortened the downtime required for the retube process, reducing the outage schedule and associated costs by 30 days. It also significantly improves the risk profile of the project, because each of the 480-channel reactors can now be replaced in just 960 heavy lifts in a space-constrained environment. This also enhances employee safety through better radiological protection. Before being applied to the Darlington project, the process received rigorous testing through theoretical analysis, proof of concept, and integration on a full-scale mock-up. Now many of its methods and tooling techniques are protected by patents in Canada and other jurisdictions.

Darlington Unit 3 was returned to service in July 2023, 169 days ahead of service.

We help our clients stay at the forefront, drive down costs and speed up reactor operational readiness by implementing this innovative combined pressure tube and calandria tube removal process.

Why does it matter?

Nuclear power is a key driver in the shift towards clean and modern energy generation.

As a reliable and sustainable source of low-carbon energy, it has a crucial role to play in accelerate our transition towards environmentally responsible energy generation. Nuclear’s continuous and dispatchable baseline power gives stability to electrical grids, supporting other variable renewable energy sources such as solar and wind.