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.
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 storeys 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.
Tritium removal facility
Tritium is a by-product of the nuclear reaction. To help keep workers safe and to minimize the amount of tritium going into the environment, a tritium removal facility was opened at the Darlington site in 1990. This plant extracts tritium from heavy water used in OPG's nuclear reactors. The tritium is safely stored in stainless steel containers within a concrete vault.
Our commitment to the future
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.