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Darlington Nuclear Generating Station

Located in the Municipality of Clarington in Durham Region (70 km east of Toronto), Ontario Power Generation’s Darlington Nuclear Generating Station is a four-unit facility responsible for generating over 20% of Ontario’s electricity needs, which is enough energy to power 2 million homes.

Explore how Darlington is an efficient and valued supplier of energy and employment in Ontario.

In this section

Quick station facts

3,512 Megawatts

Of power generated

480 Fuel channels

Per reactor

580 Metres

The Turbine Hall is nearly 6 football fields long

20% Of

Ontario’s electricity supply

Our generating station

Darlington Refurbishment

Helping continue station operations to 2055.

Learn more

14,200 Jobs

Per year


$89.9 Billion

Dollars into Ontario’s GDP

Business Performance


Of expenditures spent within Ontario

Learn more

Darlington and OPG’s commitment to the future

Darlington Nuclear, along with OPG's other generating facilities, keeps Ontario running.

Darlington also plays a vital role in keeping our air clean, and supplying large quantities of electricity with no carbon or smog emissions.

Darlington made industrial history by becoming the first nuclear station in North America to be certified under the tough ISO 14001 environmental standard.​

Reactor buildings

  • Darlington reactor buildings are made of heavily reinforced concrete (external walls 1.8 metres or 6 ft. thick) to enclose the reactors and related equipment and 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 encased i zircaloy sheathing.

Vacuum building

  • The vacuum building design is a unique safety feature of CANDU®(CANadian Deuterium Uranium) reactor.
  • This 71 metre high cylindrical concrete structure is connected to the reactor buildings by a pressure relief duct.
  • Maintained at negative atmospheric pressure, any release of radioactive steam from the pressurized systems is sucked into the vacuum building and condensed, thus preventing its release outside the station.

Turbine hall

This huge structure houses the turbines that the station uses to generate electricity and measures approximately 580 metres long by 137 metres wide by 45 metres high. It’s a space approximately six football fields long and twelve storeys high.

Fuel bays

  • These two water-filled storage bays inside the station store the used fuel once it’s been removed from the reactors.
  • The bays keep the used fuel bundles cool for at least 10 years. After that, used fuel is moved to dry storage containers.

Tritium removal facility

  • In this facility, OPG extracts tritium from heavy water used in OPG's nuclear reactors.
  • Tritium is a by-product of the nuclear reaction.
  • The extracted tritium is then safely stored in stainless steel containers within a concrete vault.

Welcome to Darlington Nuclear

Take a tour of OPG’s Darlington Generating Station.