SNC-Lavalin and its joint venture partner Aecon Group separately announced January 11 that their 50/50 partnership had been awarded a $2.75 billion contract to carry out the execution phase of the Darlington Re-tube and Feeder Replacement (RFR) scope of work by Ontario Power Generation, in support of the refurbishment of the Darlington Nuclear station.
{mosmage} The commencement of the execution phase marks the joint venture’s successful delivery of the definition phase (2012-2016) of the project, which included the construction of a full-scale reactor mock-up facility to simulate key elements of the refurbishment work and the testing of specialized tooling and to help prepare a comprehensive estimate and schedule for the project.
The execution phase of the project will involve the replacement of main reactor components using tools and methods that were developed and tested during the project’s definition phase, carried out by the JV. Each of the four Darlington Candu reactors will be taken out of service sequentially for approximately three years to allow for the replacement of fuel channels, feeder pipes, calandria tubes and end fittings.
“Following almost four years of preparation and planning, this amendment to proceed with the physical refurbishment work demonstrates OPG’s confidence in our joint venture team and in our capabilities in the nuclear industry,” said Sandy Taylor, President, Power, SNC-Lavalin.
When the reactors are fully refurbished, OPG’s Darlington station, which produces 20% of Ontario’s electricity, “will be able to provide safe, reliable, affordable and CO2-free energy to the citizens of Ontario for another 30 years,” the company said.
“Our team will immediately shift its focus to the execution phase of the project. This will include training and procurement of critical resources before the outage begins,” said Preston Swafford, Chief Nuclear Officer and Executive Vice-President, Nuclear. “Our portion of the project is expected to create approximately 300 jobs within SNC-Lavalin and another 500 jobs in Ontario. We would also like thank Canada’s Building Trades for their support on this project.’’
The first outage is targeted to begin in the fourth quarter of 2016 and it will take approximately ten years to complete the work on all four units. SNC-Lavalin’s share of the contract will be added to its Power segment backlog in first quarter of 2016.
Darlington retubing: what’s involved
The refurbishment of each of Darlington’s four reactors involves a number of steps.
Shutdown of the Reactor
The first major activity during the refurbishment will be to shut down the reactor. Systems not required for an extended period of time are placed into a safe state referred to as lay-up.
Removal of Fuel and Heavy Water
The fuel will be removed from the reactor using fuelling machines. The removed fuel will be placed in the fuel bays as we currently do. Once the reactor fuel is removed from the reactor, heavy water will be drained from the system and transferred to an appropriate storage facility. The heavy water will be processed and available for reactor use when the outage is completed.
Islanding the Refurbishment Unit from the Operating Units
Once the reactor undergoing refurbishment has been defueled, it will be separated (islanded) from the other operating units. This is done by putting up physical barriers to delineate the refurbishment island from the operating reactors. This helps OPG staff and contractors work efficiently on the reactor while reducing the impact of refurbishment on the operating units and common systems.
Replacement of Reactor Components
The reactor components will be restored or replaced. This includes removing and replacing 480 fuel channel assemblies and 960 inlet and outlet feeders per reactor. The components will be processed and placed into appropriate storage containers. The remaining components will be inspected to ensure they are acceptable for continued operation. Removing and replacing the reactor components is the critical part of the outage. OPG has applied lessons learned from past refurbishment efforts. This includes developing intensive personnel training and tool testing programs in the full scale reactor mock-up.
Turbine and Steam Generators
A majority of the turbine generator systems and auxiliary systems will be disassembled and rebuilt or replaced. OPG has concluded the steam generators will remain fit for service over the life extension period and will not require replacement. The steam generator tubes and parts will be inspected, inspection nozzles will be installed and the steam generators will be cleaned to improve heat transfer.
Balance of Plant Repair and Maintenance
The remaining scope of work is being carried out to maintain or improve the safety and reliability of the station to the post-refurbishment end of life. The scope of work includes:
• Work on nuclear systems, such as the primary heat transport system and the reactor regulating systems; and
• Work on conventional systems, such as the low pressure service water system and the fire protection system.
Return to Service of Reactors
Return to service involves returning the reactor to commercial operation, and includes demonstrating the work meets specified requirements. Return to service covers the range of activities from completing the installation work to achieving 100 per cent reactor power
Source: Ontario Power Generation