Electricity generation in Canada
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Nuclear power in Canada is provided by 19 commercial reactors with a net capacity of 13.5 gigawatt (GW), producing a total of 95.6 terawatt-hours (TWh) of electricity, which accounted for 16.6% of the country's total electric energy generation in 2015. All but one of these reactors are located in Ontario, where they produced 61% of the province's electricity in 2019 (90.4 TWh).^[1] Seven smaller reactors are used for research and to produce radiopharmaceuticals for use in nuclear medicine.

All currently operating Canadian nuclear reactors are a type of pressurized heavy-water reactor (PHWR) of domestic design, the CANDU reactor. CANDU reactors have been exported to India, Pakistan, Argentina, South Korea, Romania, and China. While there are (as of 2022) no plans for new CANDUs in Canada or elsewhere, Canada remains a technology leader in heavy water reactors and natural uranium fueled reactors more broadly. The Indian IPHWR-line is an indigenized derivative of the CANDU while only a small number of pressurized heavy water reactors were built independent of the CANDU-line, mainly Atucha nuclear power plant in Argentina.

History

The nuclear industry (as distinct from the uranium industry) in Canada dates back to 1942 when a joint British-Canadian laboratory, the Montreal Laboratory, was set up in Montreal, Quebec, under the administration of the National Research Council of Canada, to develop a design for a heavy-water nuclear reactor. This reactor was called the National Research Experimental (NRX) reactor and would be the most powerful research reactor in the world when completed.

Experimental reactors

In 1944, approval was given to proceed with the construction of the smaller ZEEP (Zero Energy Experimental Pile) test reactor at Chalk River Nuclear Laboratories in Ontario and on September 5, 1945, at 3:45 p.m., the 10-watt ZEEP achieved the first self-sustained nuclear reaction outside the United States.^[2]

In 1946, the Montreal Laboratory was closed, and the work continued at the Chalk River Nuclear Laboratories. Building partly on the experimental data obtained from ZEEP, the National Research Experimental (NRX)—a natural uranium, heavy water moderated research reactor—started up on July 22, 1947. It operated for 43 years, producing radioisotopes, undertaking fuels and materials development work for CANDU reactors, and providing neutrons for physics experiments. It was eventually joined in 1957 by the larger 200 megawatt (MW) National Research Universal reactor (NRU).

From 1967 to 1970, Canada also developed an experimental miniature nuclear reactor named SLOWPOKE (acronym for Safe LOW-POwer Kritical Experiment). The first prototype was assembled at Chalk River and many SLOWPOKEs were built, mainly for research. Two SLOWPOKEs are still in use in Canada and one in Kingston, Jamaica; one has been running at École Polytechnique de Montréal since 1976, for instance.

Nuclear power plants

In 1952, the Canadian government formed Atomic Energy of Canada Limited (AECL), a Crown corporation with the mandate to develop peaceful uses of nuclear energy. A partnership was formed between AECL, Ontario Hydro and Canadian General Electric to build Canada's first nuclear power plant, Nuclear Power Demonstration (NPD). The 20 MW_e NPD started operation in June 1962 and demonstrated the unique concepts of on-power refuelling using natural uranium fuel, and heavy water moderator and coolant. These features formed the basis of a fleet of CANDU power reactors (CANDU is an acronym for CANada Deuterium Uranium) built and operated in Canada and elsewhere. Starting in 1961, AECL led the construction of 24 commercial CANDU reactors in Ontario, Quebec, and New Brunswick.

The first full-scale CANDU reactor entered service on September 26, 1968, at Douglas Point on the shore of Lake Huron in Ontario. Two years later a reactor of comparable power but of a different design became operational along the Saint Lawrence River in Quebec. Gentilly-1 was a prototype CANDU-BWR reactor with features intended to reduce its cost and complexity. After the equivalent of only 180 on-power days over nearly seven years (a 5.7% lifetime capacity factor), Gentilly-1 was closed in June 1977.^[3] Douglas Point, also suffering from unreliability with a lifetime capacity factor of 55.6%, was deemed a financial failure and shut down in May 1984.^[4]

In August 1964, Ontario Hydro decided to build the first large-scale nuclear power plant in Canada at Pickering on Lake Ontario, only 30 kilometres from downtown Toronto to save on transmission costs. To reduce cost the reactors share safety systems including containment and the emergency core cooling system. Pickering A station started operations in 1971 at a cost of $716 million (1965). It was followed by the Bruce A station, built in 1977 at a cost of $1.8 billion on the same site as the Douglas Point reactor. Beginning in 1983 four B reactors were added to the existing Pickering units, with all of them sharing the same common infrastructure as the A reactors. The final cost for these four new reactors was $3.84 billion (1986). Likewise for $6 billion, four new reactors were added to the Bruce site starting in 1984, but in a separate building with their own set of shared infrastructure for the new reactors. After a loss of coolant accident occurred at Pickering reactor A2 in August 1983, four of the reactors had their pressure tubes replaced between 1983 and 1993 at a cost of $1 billion (1983).^[5]

As most of the development of nuclear energy was taking place in Ontario, Quebec nationalists were eager to benefit from a promising technology. Hydro-Quebec initially planned to build as many as 40 reactors in the province, but the government chose to pursue hydroelectric mega-projects instead (see the James Bay Project). At the end of the 1970s, public opinion about nuclear energy shifted, and only one new reactor at Gentilly was operational by 1983. The same year, another reactor began operation at Point Lepreau, New Brunswick, a province longing to diversify its energy sources since the oil crisis of 1973.^[6]

In 1977, a new plant close to Toronto, Darlington, was approved for completion in 1988 at an estimated cost of $3.9 billion (1978). After much controversy the last unit came into service five years late. By then the cost had ballooned to $14.4 billion (1993).^[7] In the wake of this cost, a Darlington B plant was cancelled. At this point, the operating Canadian reactors fleet consisted of eight units at the Pickering site, eight units at the Bruce site, four units at the Darlington site, one unit at Gentilly in Quebec, and one unit at Point Lepreau in New Brunswick for a 14.7 GW_e net total operational installed capacity.

Refurbishment or closure

By 1995 the Pickering and Bruce A units needed refurbishment as after 25 years effective full power years of operation, the embrittled fuel channels face an increased risk of rupture and must be replaced. The first reactor to close was Bruce A unit 2 in November 1995 because of a maintenance accident.^[8] After criticism of Ontario Hydro plants management and a series of incidents,^[9] on December 31, 1997, the four A reactors at Pickering and unit 1 at Bruce A were abruptly shut down. They were followed by the remaining two Bruce A units three months later. Over 5 GW of Ontario's electric capacity was abruptly shut down, but at this point, the reactors were supposed to restart at six-month intervals starting in June 2000.^[5]

In 1999, indebted Ontario Hydro was replaced by Ontario Power Generation (OPG). The next year, OPG leased its Bruce A and B nuclear stations to Bruce Power, a consortium led by British Energy. Pickering's A4 and A1 reactors were refurbished from 1999 to 2003 and from 2004 to 2005, respectively. To prevent a power shortage while phasing out Ontario's coal-burning plants, Bruce A units 3 and 4 were returned to service in January 2004 and October 2003 respectively, and then units 1 and 2 were completely refurbished for $4.8 billion (2010).^[10] Of the eight units laid down, four were refurbished, two were restarted without refurbishment, and two (Pickering A2 and A3) were definitively shut down.

In April 2008, refurbishment began at Point Lepreau and had been estimated to be completed in September 2009 at a cost of $1.4 billion. Plagued by delays, the work was finalized three years late and largely over budget.^[11] Hydro-Quebec had decided in August 2008 to similarly refurbish Gentilly-2 starting in 2011. Because of delays with the Point Lepreau rebuild, and for economic reasons in a province with hydroelectricity surpluses, the plant was permanently shut down in December 2012.^[8] It should remain dormant 40 more years before being dismantled.^[12]

Following the 2011 Japanese nuclear accidents, the Canadian Nuclear Safety Commission (CNSC) ordered all reactor operators to revisit their safety plans and report on potential improvements by the end of April 2011.^[13] The International Atomic Energy Agency (IAEA) later conducted a review of the CNSC's response to the events at Japan's Fukushima Daiichi Nuclear Power Plant, and concluded that it was "prompt, robust and comprehensive, and is a good practice that should be used by other regulatory bodies".^[14]

Massive refurbishments

As of 2022, OPG are planning to shut down the 2 Pickering A units by 2024 and keep the Pickering B units operating through to 2026. However, OPG reviewed its operational plan and decided that Pickering B could continue operations through to 2026 and are reassesing the feasibility of refurbishing the four Pickering B units and adding another 30 years of operation to their life.^[15] Meanwhile, the Darlington reactors are gradually undergoing a $12.8 billion complete refurbishment currently underway on Units 1 and 3 while Unit 2 successfully completed its refurbishment in 2020. Bruce Power will follow the same plan for its 8 CANDU-750 units. This even more massive undertaking started in January 2020 and should cost $13 billion.^[16] The newly refurbished Darlington and Bruce reactors should then be operating until at least 2050 and through to 2064. To compensate for the programmed shut down of numerous reactors, the Government of Ontario decided in January 2016 to push the retirement date of the Pickering A plant to 2024 while reviewing the possibility of refurbishing Pickering B.^[17]

New reactor proposals

Rising fossil fuel prices, an aging reactors fleet, and new concerns about reducing greenhouse gas combined to promote the building of new reactors throughout Canada during the early 2000s. However, what was seen as a nuclear renaissance petered, no new construction has started.

Ontario

Bruce site

In August 2006, Bruce Power applied for a licence to prepare its Bruce site for the construction of up to four new nuclear power units. In July 2009, the plan was shelved as a declining demand for electricity did not justify expanding production capacity. Bruce Power prioritized refurbishing its A and B plants instead.^[18]

Darlington site

In September 2006, OPG applied for a licence to prepare its Darlington site for the construction of up to four new nuclear power units. The reactor designs being first considered for this project were AECL's ACR-1000, Westinghouse's AP1000 and Areva's EPR. In 2011, the Enhanced CANDU 6 entered the competition and soon became OPG's favourite.^[18][19] On August 17, 2012, after environmental assessments, OPG received a Licence to Prepare Site from the CNSC.^[20] In 2013, the project was put on hold as OPG decided to concentrate on refurbishing the existing Darlington units.^[21]

In October 2013, the Ontario government declared that the Darlington new build project would not be a part of Ontario's long term energy plan, citing the high capital cost estimates and energy surplus in the province at the time of the announcement.^[22]

In November 2020, OPG resumed licensing activities, this time for the construction of a small modular reactor (SMR).^[23]

Alberta

Energy Alberta Corporation announced August 27, 2007, that they had applied for a licence to build a new nuclear plant in Northern Alberta at Lac Cardinal (30 km west of the town of Peace River), for two ACR-1000 reactors going online in 2017 as steam and electricity sources for the energy-intensive oil sands extraction process, which uses natural gas.^[24] However, a parliamentary review suggested placing the development efforts on hold as it would be inadequate for oil sands extraction.^[25]

Three months after the announcement, the company was purchased by Bruce Power^[26] who proposed expanding the plant to four units for a total 4 GW_e.^[27] These plans were upset and Bruce withdrew its application for the Lac Cardinal in January 2009, proposing instead a new site 30 km north of Peace River.^[28] Finally, in December 2011, the controversial project was abandoned.^[29]

On January 15, 2024, Alberta's Capital Power Corporation entered an agreement with Ontario Power Generation to jointly assess the feasibility of deploying Small Modular Reactors (SMRs) in Alberta. Assessments will take place over 2 years, and includes assessing scalability, and ownership & operating structures.^[30]

Saskatchewan

The Government of Saskatchewan was in talks with Hitachi Limited's Power Systems about building a small nuclear plant in the province involving a five-year study beginning in 2011.^[31]

A study in 2014 showed public support for nuclear power and highlighted a reliable supply of uranium ore in the province,^[32] but the province has not been eager moving forward and no site has been identified since 2011.^[31]

New Brunswick

In August 2007, a consortium named Team CANDU began a feasibility study regarding the installation of an Advanced CANDU Reactor at Point Lepreau, to supply power to the eastern seaboard. July 2010, the Government of New Brunswick and NB Power signed an agreement with Areva to study the feasibility of a new light water nuclear unit at Point Lepreau but a newly elected government two months later shelved the plan.^[33]

Other technologies

A number of Canadian startups are developing new commercial nuclear reactor designs.^[34] In March 2016, the Oakville, Ontario-based company Terrestrial Energy was awarded a $5.7 million grant by the Government of Canada to pursue development of its small IMSR Molten Salt Reactor.^[35] Thorium Power Canada Inc., from Toronto, is seeking regulatory approvals for a thorium-fuelled compact demonstration reactor to be built in Chile that could be used to power a 20 million-litre/day desalination plant. Since 2002, General Fusion, from Burnaby, British Columbia, has raised $100 million from public and private investors to build a fusion reactor prototype based on magnetized target fusion starting in 2017.^[36]

Generation

Nuclear electricity production, nationally and by province, per year^[37]

	1980		1985		1990		1995[38]		2000[39]		2005		2010		2015[40]		2020
	TWh	%Total	TWh	%Total	TWh	%Total	TWh	%Total	TWh	%Total	TWh	%Total	TWh	%Total	TWh	%Total	TWh	%Total
Canada	35.8	9.8%	57.1	12.8%	68.8	14.8%	92.3	17.2%	68.6	11.8%	86.8	14.5%	85.5	14.5%	95.6	16.6%
Ontario[1]	35.8	32.6%	48.5	40%	59.3	45.9%	86.2	58.5%	59.8	39%	77.9	49.2%	82.9	55%	92.3	60%	87.8	60%
Quebec[41]	0	0%	3.21	2.3%	4.14	3.1%	4.51	2.6%	4.88	2.7%	4.48	2.5%	3.76	2%	0	0%	0	0%
New Brunswick	0	0%	5.43	47.5%	5.33	32%	1.57	12.5%	3.96	21.1%	4.37	21.6%	0	0%	3.3

Power reactors

Bruce A/B
Douglas Point

Gentilly

NPD

Pickering A/B
Darlington

Point Lepreau

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Nuclear plants in Canada (view)
 Active plants
 Closed plants

Beginning in 1958, Canada built 25 nuclear power reactors over the course of 35 years, with only three of them located outside of Ontario. This made the southern part of the province one of the most nuclearized areas in the world with 12 to 20 operating reactors at any given time since 1987 inside a 120-kilometre radius.

All of the Canadian reactors are concentrated in only seven different sites, with two of them (Pickering and Bruce) being the largest nuclear generating stations in the world by total reactor count. The Bruce site, with eight active reactors and one shut down (Douglas Point) has been the largest operating nuclear power station in the world by total reactor count, the number of operational reactors, and total output between 2012 and 2020.

All of the reactors are of the PHWR type. Because CANDU reactors can be refuelled while operating, Pickering unit 3 achieved the then highest capacity factor in the world in 1977 and Pickering unit 7 held the world record for continuous operation without a shutdown (894 days) from 1994 to 2016.^[42][43] In 2021, a new world record (1106 days) was established by Darlington unit 1.^[44] Overall, PHWR reactors had the best lifetime average load factor of all western generation II reactors until being superseded by the PWR in the early 2000s.^[39]

Canada's nuclear power reactors Timeline^[45]

Active