Ontario Power Generation (OPG) has sought approval to refurbish the Darlington Nuclear Generating Station in Clarington; Darlington Nuclear Generating Station is one of the largest nuclear power plants in North America.
The Darlington Refurbishment Project involves the refurbishment of the four reactors at Darlington to enable continued operations for approximately 25 to 30 additional years past their original operating lifespan.
Darlington Nuclear, along with OPG’s other generating facilities, plays an important role in keeping Ontario running. It also plays a vital role in keeping our air clean, and will continue to produce large quantities of electricity with no smog producing emissions. In fact, Darlington made industrial history by becoming the first nuclear station in North America to be certified under the tough ISO 14001 environmental standard.
OPG’s Darlington Nuclear Generating Station is a four-unit station with a net output of 3,512 megawatts (MW). Located in the Municipality of Clarington in Durham Region, 70 km east of Toronto, Darlington Nuclear provides about 20 per cent of Ontario’s electricity needs, enough to serve a city of two million people.
Darlington Nuclear, along with OPG’s other generating facilities, plays an important role in keeping Ontario running. It also plays a vital role in keeping our air clean, and will continue to produce large quantities of electricity with no smog producing emissions. In fact, Darlington made industrial history by becoming the first nuclear station in North America to be certified under the tough ISO 14001 environmental standards.
The reactor buildings at Darlington are each made of heavily reinforced concrete (external walls 1.8 m or 6 ft. thick) to enclose the reactors and related equipment. Interior concrete walls also shield personnel from radiation during operation. Each building contains one reactor and four steam generators (boilers). The reactor consists of a large, heavily shielded vessel or calandria, which contains 480 fuel channels and 6,240 bundles of uranium fuel that are encased in zircaloy sheathing.
This 71 m high cylindrical concrete structure is connected to the reactor buildings by a pressure relief duct and is a unique safety feature of the CANDU system. The vacuum building is maintained at negative atmospheric pressure. Any release of radioactive steam from the pressurized systems would be sucked into the vacuum building, thus preventing its release outside the station.
This structure houses the turbine hall. It measures approximately 580 m long by 137 m wide by 45 m high, a space that’s approximately six football fields long, and twelve story high.
Irradiated fuel bays
Two water-filled pools inside the station store the irradiated fuel once it’s been removed from the reactors. The pools keep the fuel cool and shield station workers from radiation. Eventually the used fuel will be moved to dry storage containers.
Darlington Major Refurbishment Work package
Darlington Refurbishment is made up of many individual projects of various scales and size. Six major project work packages are:
- Retube and feeder replacement (RFT): This work includes the removal and replacement of pressure tubes, calandria tubes and feeders in each reactor. This is the largest work package and is the core to success of refurbishment. It represents the majority of the refurbishment critical path schedule.
- Turbine Generators: This work package consists of inspections and repairs of the four turbine generator sets and the replacement of analog control system with new digital control system.
- Fuel Handling: this project involves the defueling of the reactor and refurbishment of the fuel handling equipment.
- Facility and infrastructure Projects: These are required to execute refurbishment and extend Darlington station life. There are more than 20 smaller scale projects such as Water and Sewer, Heavy Water Storage, Auxiliary Heating System, Electrical Power Distribution, and Refurbishment Project Office.
- Balance of Plant: This work consists of a number of smaller projects to replace or repair of components on the reactor side of the unit, such as heavy water and cooling systems, and on the conventional side of the unit such as electrical system, piping and valve work.
- Steam Generators: This includes mechanical cleaning, water lancing, inspection and maintenance work of the generators.
Canadian Nuclear Global Services Inc. (CNG Nuclear) experts have worked on Darlington and similar projects including Design, construction and supply of Heavy Water Vapor Recovery Dryers, Ion Exchange Columns, Flow elements, Recombines, Filters, Motor Operated Valves, Fukashima Projects, and now proud to utilize their expertise in Refurbishment Projects of Darlington.