Innovation success at Darlington RFR Project

Background

The nuclear industry has a long history in Canada, with the CANDU^Ò (Canadian Deuterium Uranium) reactors setting a high standard for its design and innovation. The Darlington nuclear generating station is Canada’s second largest nuclear facility by total energy output and provides 20% of Ontario’s electricity. These reactors were built in the early 1990s and are now in need of refurbishment and modernization to continue operating safely and efficiently over the next three decades.

In 2016, SNC-Lavalin entered into a joint venture (JV) with Aecon Group for a $2.75 billion contract to carry out the execution phase of the Darlington Retube and Feeder Replacement (RFR) scope of work as part of the refurbishment of the Darlington Nuclear station. The project will give new life to the CANDU reactors to ensure Ontario continues to benefit from safe and reliable baseload energy for decades to come.

As Canada’s largest clean energy project, significant planning was needed prior to commencing on-site work at the reactor. The team needed to create a detailed execution plan that identified the materials, parts and steps to successfully execute this complex project. To extend the life of the reactor each of the four CANDU reactors will be taken out of service sequentially, allowing for the replacement of reactor internals. The impact of these outages can be costly, costing up to $1 million per day for a utility and therefore presents a strong incentive to accelerate the timeline, while maintaining the same safety standards and high-quality work.

Approach

SNC-Lavalin fully prepares for any client project, but due to the complexity of this project it required meticulous detail and planning. The replacement of 480 fuel channels and associated components of the reactor is complex because there are many different considerations in relation to the operations and logistics. This life extension project provides an opportunity to identify how new technologies, best practices and innovations can improve project outcomes while maintaining safety, cost and overall efficiency. During this review our teams identified an opportunity to create the life extension outage reduction initiative leading to a significant reduction in the amount of time required to refurbish each CANDU reactor.

Innovation

Canada’s nuclear sector is well recognized for its best in class technology and ongoing innovations. SNC-Lavalin is no different with innovation extending across our nuclear services, from optimizing reactor designs to reducing waste at nuclear sites.

The Darlington project provided us with an opportunity to create more innovation.

When removing and replacing fuel channels and associated components in a 480-channel CANDU reactor there are typically 1,920 multi-tonne heavy lifts required. Through discussions and preliminary assessments using historical data, our teams identified, developed and patented a tooling method that combines the removal of the pressure tubes and calandria tubes in one extraction, instead of two, thereby shortening the down-time required for the retube process resulting in significant cost savings. This innovation significantly improved the risk profile of the project as it reduced the number of multi-tonne heavy lifts in a space constrained environment from 1,920 to just 960 in a 480-channel reactor. The tooling innovation also enhances employee safety through improved radiological protection. Before applying this new process to the Darlington project, the process was rigorously tested by theoretical analysis, proof of concept and integrated on a full-scale mock-up. To protect the intellectual property innovations, many of the methods and tooling have either been patented or have patents pending in Canada and other jurisdictions.

This tooling success is just another example of our long history of innovation, including the ability of CANDU reactors use several alternative fuels, such as recovered uranium (RU) from the reprocessing of light water reactor (LWR) spent fuel, plutonium (Pu) mixed oxide, and thorium-based fuels, as well as conventional natural uranium fuel. This improves uranium resource utilization rates and reduces fuel costs for utilities.

We have also developed an Advanced Portable Polymer Tester (APPT) to inspect, analyze and report on the condition of our customers’ polymer cables. Through data analysis, we can evaluate the level of cable irradiation and make recommendations on fitness for service, saving the time and cost of unnecessarily replacing the cables and reducing waste.

Outcome and client benefit

By rethinking older processes and methods we encourage innovation that will, deliver results for our clients and lead to improved processes, increased productivity and enhanced the safety of workers and sites. 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.

Our client can now benefit from a reduction of 30 days to the outage schedule and associated costs.