Darlington Life Extension Project Fuel and heavy water removal Fuel is removed from the reactor using fuelling machines and placed in fuel bays. Once the reactor fuel is removed, heavy water (D 2 0) is drained from the system and transferred to an appropriate storage facility. The D 2 0 is processed and made available for reactor use when the outage is complete. Islanding the refurbishment unit from operating units Once the reactor has been defueled, it is separated (or “islanded”) from the other operating units by physical barriers. Reactor component replacement The reactor components are restored or replaced. At the Darlington units, this includes the removal and replacement of 480 fuel channel assemblies and 960 feeders per reactor. Inspections are conducted on the remaining components to ensure they are acceptable for continued operation. Turbine and steam generator replacement Majority of the turbine generator systems and auxiliary systems are disassembled and rebuilt or replaced. Steam generator tubes and parts are inspected, inspection nozzles are installed and the steam generators are cleaned to improve heat transfer. Balance of plant refurbishment Remaining scope of work is carried out to maintain or improve the safety and reliability of the reactor. Return to service In this final stage, the reactor is returned to commercial operation. The life extension lifecycle Reactor shutdown The first major activity during the refurbishment is to safely shut down the reactor. Ontario Power Generation’s (OPG) Darlington Nuclear Generating Station (DNGS) meets approximately 20 percent of Ontario’s electricity needs. In operation since the early 1990s, the CANDU reactors® are now approaching the mid-point of their operating life. At this stage, a life extension outage is required to replace or refurbish major reactor components, crucial to delivering the electricity required to power Canada’s most populous province. SNC-Lavalin Inc. and its joint venture (JV) partner were awarded several contracts by OPG to carry out many aspects of the Darlington Refurbishment Project—the largest, clean energy project in Canada. The JV will perform and manage all aspects of the work including engineering, procurement, construction and project management.
Transcript
Darlington Life Extension Project
Fuel and heavy water removal Fuel is removed from the reactor using fuelling machines and placed in fuel bays. Once the reactor fuel is removed, heavy water (D20) is drained from the system and transferred to an appropriate storage facility. The D20 is processed and made available for reactor use when the outage is complete.
Islanding the refurbishment unit from operating unitsOnce the reactor has been defueled, it is separated (or “islanded”) from the other operating units by physical barriers.
Reactor component replacementThe reactor components are restored or replaced. At the Darlington units, this includes the removal and replacement of 480 fuel channel assemblies and 960 feeders per reactor. Inspections are conducted on the remaining components to ensure they are acceptable for continued operation.
Turbine and steam generator replacementMajority of the turbine generator systems and auxiliary systems are disassembled and rebuilt or replaced. Steam generator tubes and parts are inspected, inspection nozzles are installed and the steam generators are cleaned to improve heat transfer.
Balance of plant refurbishmentRemaining scope of work is carried out to maintain or improve the safety and reliability of the reactor.
Return to serviceIn this final stage, the reactor is returned to commercial operation.
The life extension lifecycle
Reactor shutdownThe first major activity during the refurbishment is to safely shut down the reactor.
Ontario Power Generation’s (OPG) Darlington Nuclear Generating Station (DNGS) meets approximately 20 percent of Ontario’s electricity needs. In operation since the early 1990s, the CANDU reactors® are now approaching the mid-point of their operating life. At this stage, a life extension outage is required to replace or refurbish major reactor components, crucial to delivering the electricity required to power Canada’s most populous province.
SNC-Lavalin Inc. and its joint venture (JV) partner were awarded several contracts by OPG to carry out many aspects of the Darlington Refurbishment Project—the largest, clean energy project in Canada.
The JV will perform and manage all aspects of the work including engineering, procurement, construction and project management.
Definition Phase (2012 - 2016)
The Definition Phase included design, supply and testing of special retube and feeder replacement tooling, procurement of all replacement reactor components, design and construction of several site facilities and completion of all plant engineering.
Tooling DesignThe four reactor cores will be replaced sequentially using remotely-operated electro-mechanical tooling systems that we developed, manufactured and tested during the Definition Phase. These tooling systems, a best practice in the industry, do the heavy lifting and precision fitting while reducing worker exposure to radiation. The tools were based on proven designs used on other CANDU® life extension projects and were customized for the Darlington reactors.
An innovative approachThe project scope also included the design and construction of a full scale reactor mock-up at the Darlington Energy Complex (DEC) to simulate key elements of refurbishment work. The tooling systems’ performance was proven on the mock-up in realistic conditions, allowing staff to practice tasks and perfect techniques using the actual tools and protective equipment before beginning work inside the reactor vault. This ensured workers were thoroughly trained and tested in a safe, realistic and controlled environment with all the obstacles, constraints and potential challenges they may face during the actual work.
Constructed for the refurbishment project, the DEC isa 350,000 square-foot, world-class nuclear training facility. In addition to being home to the full-scale reactor mock-up, it also includes 75,000 square-foot of warehouse for retube and feeder components and equipment and extensive training facilities and classrooms. Retube Waste Processing Building The JV is responsible for the design, construction, and commissioning of the 75,000 square-foot Retube Waste Processing Building (RWPB). This is a temporary facility, where we will process, stage and package Low and Intermediate Level Waste (L&ILW) produced during the Refurbishment project. The RWPB will house the Waste Tooling System (WTS) which processes (crushes, cuts and packs) irradiated reactor components that have been removed from the reactor into concrete and steel lined Retube Waste Containers.
Execution Phase (2016 – 2026)
The field execution began in October 2016, after many years of detailed planning and preparations. Each unit outage is expected to last approximately three years, beginning with Unit 2.
Heavy Water Management BuildingThe Heavy Water Storage and Drum Handling Facility project will provide a heavy water storage facility during the refurbishment and support ongoing station operations. The project will also implement improvements for heavy water management at the Tritium Removal Facility (TRF) including the increase of operational storage.
The JV assumed the building in a partial state of construction, where the basement walls and slab were poured by a previous contractor. The JV took on the completion of the engineering packages as they were left and completion of all construction activities.
Turbine Generator Refurbishment The JV will refurbish the turbine generator (TG) at each of the four Darlington units. During Definition phase, it was determined that there are no life-limiting issues to the TG sets. However, during the Darlington Refurbishment, the JV is responsible for all engineering integration work using OPG’s Engineering Change Control (ECC) configuration management process, in addition to all factors that may have an impact on the remaining life of the sets will be addressed.
Factors include inspections, repairs and/ or replacements of: › Steam turbine and turbine auxiliaries
