Canada’s nuclear future brightens
Although the Canadian and US nuclear industries have shared origins in World War II, their paths soon diverged.
Physics Today 74, 1, 23 (2021); https://doi.org/10.1063/PT.3.4653
On a windswept field near the shores of Lake Ontario in mid-November, Canadian politicians and nuclear industry executives gathered to announce plans to build the country’s first new nuclear reactor since the early 1990s. A month earlier US Department of Energy Secretary Dan Brouillette and Romania’s Minister of Economy, Energy, and Business Environment Virgil Popescu signed an $8 billion agreement in Washington, DC, that paves the way for the construction of two new Canadian-origin reactors at a nuclear power plant on the Black Sea. Two Canadian reactors are already located there.
The two events highlight differences between the Canadian nuclear industry and its counterpart in the US. As competitive pressures have forced the closure of nuclear power stations and threaten many others south of the border, Canadians are in the midst of major refurbishments to extend the lives of a dozen reactors; another has already been updated. Six other aging reactors are due to be shut down by 2025, and it’s likely that some new nuclear plants will eventually replace them.
Canada’s 19 operating power reactors all have a markedly different design from the light-water reactors (LWRs) that predominate in the US and around the world. Known as CANDUs (Canadian deuterium uranium), they employ heavy water (deuterium oxide) as the neutron moderator and coolant. Should current plans proceed, however, the next Canadian reactor will be of a new type altogether.
Ontario Power Generation (OPG), the provincial government utility that owns the province’s 18 reactors, is to select one of three competing designs for a single small modular reactor (SMR) to be built at its Darlington Nuclear Generating Station roughly 80 kilometers east of Toronto. GE Hitachi Nuclear Energy, X-Energy, and Terrestrial Energy are finalists in the competition, said Ken Hartwick, OPG’s president and CEO. The target date for startup is 2028.
A rendering of a small modular reactor design from SNC-Lavalin. The heavy-water-moderated reactor would produce 300 MW of electricity.
Additional SMR orders from Saskatchewan, New Brunswick, and Alberta will follow, predicted Greg Rickford, Ontario’s minister of energy, northern development, and mines and of indigenous affairs. In a December 2019 memorandum of understanding, the four provinces agreed to cooperate on advancing development and deployment of SMRs.
Nuclear power in Canada has always been centered in Ontario, the most populous and industrialized of the 13 provinces and territories. Roughly 60% of the electricity consumed in the province is from nuclear. The only CANDU outside Ontario supplies about one-third of New Brunswick’s electricity. British Columbia, Manitoba, and Quebec have abundant hydroelectric resources, and Quebec, which exports power, closed its only CANDU in 2012, electing to forgo the expense of refurbishment. Alberta, Saskatchewan, and the maritime provinces are more sparsely populated and rely mainly on fossil fuels.
Heavy and light water
Canada’s nuclear program dates to World War II, when the UK relocated its atomic bomb program from Cambridge University to its North American dominion. In Montreal and later at Chalk River Laboratories, about 180 kilometers upstream of Ottawa, British and Canadian scientists were focused on developing a heavy-water-moderated reactor to produce plutonium for the Manhattan Project. The British had brought along a large quantity of heavy water that had been smuggled out of occupied France. The Zero Energy Experimental Pile (ZEEP) at Chalk River, the first operating nuclear reactor outside the US, was a heavy-water design.
Ultimately, the US nuclear bomb development program chose graphite to be the neutron moderator for the reactors that made the plutonium for the Nagasaki bomb. But Canada’s National Research Experimental (NRX) reactor, the successor to ZEEP, was the basis for the heavy-water plutonium and tritium production reactors at DOE’s Savannah River Site, says historian Robert Bothwell, author of Nucleus: The History of Atomic Energy of Canada Limited (1988).
Some of the R&D in support of Hyman Rickover’s nuclear propulsion program for the US Navy was done at the NRX, although the navy chose light water as the moderator and coolant for submarine reactors. President Jimmy Carter, who was then a navy lieutenant, was assigned to assist the cleanup of a 1952 partial meltdown of the NRX, the world’s first major nuclear accident.
The National Research Universal (NRU) heavy-water research reactor began operating at Chalk River in 1957. In addition to developing fuels for CANDUs and conducting materials research, the NRX and NRU produced medical radioisotopes. At times the NRU supplied more than half the world’s molybdenum-99, the precursor to technetium-99m, the most widely used medical isotope. When it was permanently shut down in 2018, the NRU was the world’s oldest operating nuclear reactor. Two dedicated replacement isotope-production reactors at Chalk River, completed by a public–private partnership, were plagued by design faults and were abandoned in 2008.
The Bruce Nuclear Generating Station on Lake Huron is the largest nuclear power plant in North America. Its eight CANDU reactors produce 30% of Ontario’s electricity. Four of the reactors are in the foreground; the others are visible in the background.
BRUCE POWER
Canada never developed nuclear weapons, but Canadian mines and uranium processing facilities played key roles in the Manhattan Project and in the postwar US nuclear arms buildup. In Port Hope, Ontario, a former radium processing plant now owned by Cameco Corp was converted during World War II to refine high-grade uranium from the Belgian Congo. Today it exports uranium hexafluoride to enrichment plants for peaceful purposes only. It also produces uranium dioxide for CANDU fuel.
The Cold War arms race fueled a boom in uranium mining at Elliot Lake in northern Ontario. Joseph Hirshhorn, whose collection of art now populates the Smithsonian museum that bears his name, made much of his fortune from Elliot Lake. When the US Atomic Energy Commission began cutting back on uranium orders in the late 1950s, the boomtown went bust. Canada is today the world’s second-largest exporter of uranium, all of which is now mined in Saskatchewan’s Athabasca River basin, whose ore has a higher grade than Elliot Lake’s.
As partner in the North American Aerospace Defense Command and a NATO member, Canada once fielded US nuclear warheads on surface-to-air missiles and aircraft, says Tim Sayle, assistant professor of history at the University of Toronto. Canada has been free of nuclear weapons since the early 1980s.
Enrichment not required
With encouragement from the government, the US Navy submarine reactor technology was adapted by US utilities for electricity production. All operating commercial reactors in the US are LWRs. But Canada continued to develop its heavy-water technology. In large part, the CANDU design stemmed from Canada’s inability to manufacture large castings for the pressure vessels that encapsulate LWR nuclear fuel assemblies, says Colin Hunt, cochair of the government and regulatory affairs committee of the Canadian Nuclear Society.
The CANDU reactor core consists of a calandria, an unpressurized vessel of heavy water with hundreds of tubes running through it to contain the nuclear fuel. Whereas LWRs must be shut down every 12–18 months to be refueled, CANDUs were designed to allow on-line refueling. The reactors remain operating as fresh fuel bundles are inserted into the tubes and the spent ones are ejected. LWR uranium fuel must be enriched to around 4% in the fissile uranium-235 isotope, but the CANDU burns naturally occurring uranium fuel containing about 0.7% 235U. That feature eliminates the need for costly enrichment plants or services. And the CANDU can burn other fuels, including thorium, plutonium, and even spent fuel from LWRs.
The first CANDU, at Douglas Point on the shores of Lake Huron, operated commercially from 1968 to 1984. Four larger CANDUs came on line at the Pickering Nuclear Generating Station near Toronto in 1971, and four more units were added there in 1983. Six remain in operation. Twelve more CANDUs were built in Ontario, eight at the Bruce Nuclear Generating Station at Douglas Point and the newest four at Darlington. Today, Bruce is the largest nuclear generating station in North America, supplying more than 30% of Ontario’s electricity.
Outside Canada, CANDUs have been installed in Argentina (1), China (2), India (2), Pakistan (1), Romania (2), and South Korea (4). Following India’s 1974 test of a nuclear weapon, Ottawa ended nuclear cooperation with New Delhi. India went on to build more than a dozen reactors of a CANDU-derived design. Canada’s assertive efforts to sell CANDUs to the UK were unsuccessful. Had the UK bought any, Bothwell says, the CANDU likely would have become a joint venture between the two nations, and the technology might have become the world’s dominant reactor model.
An uncertain future
The aging Pickering reactors, which supply about 15% of Ontario’s power, are scheduled to be permanently closed by 2025. It’s an open question what will replace them. The other major power source in Ontario, hydroelectric, has been fully tapped, says Hunt. Coal-fired generation in the province is prohibited by law, and a recently enacted federal carbon tax of Can$30 ($23) per ton of carbon dioxide, rising to Can$50 in two years, should discourage new natural-gas-fired plants.
Although the province’s electricity demand isn’t growing now, it will likely increase as demand for electric vehicles and hydrogen grows, says William Fox, executive vice president for nuclear at SNC-Lavalin, an architect and engineering firm that holds the rights to CANDU technology.
Created during the Manhattan Project, the Chalk River Laboratories north of Ottawa were home to CANDU heavy-water-reactor development and several research reactors. Now known as Canadian Nuclear Laboratories, the facility is operated by a consortium of companies led by SNC-Lavalin for the federal government.
CANADIAN NUCLEAR LABORATORIES
At the federal level, the Liberal-led government of Justin Trudeau has begun considering legislation with the aim of reducing Canada’s carbon emissions to zero by 2050. On 30 November the government announced its intention “to launch an SMR Action Plan by the end of 2020 to lay out the next steps to develop and deploy this technology.” It’s a sign that Liberal members of Parliament have recognized that nuclear power is needed if Canada hopes to meet its 2015 Paris Agreement pledge that by 2030 it will have cut greenhouse gas emissions by 30% from their 2005 levels, says John Barrett, a consultant and former Canadian ambassador to the International Atomic Energy Agency.
Increasing wind and solar energy seems an obvious option to meet Ontario’s future needs. But its leaders have soured on renewables since the previous Liberal provincial legislature’s heavy subsidization of wind energy led to enormous increases in electricity rates. From 2010 to 2016, average home electricity costs rose by 32%, despite a 10% decline in average household electricity consumption, according to Ontario’s Financial Accountability Office. The price hikes, which also caused many industrial operations to flee the province, were a major contributor to the Liberals’ historic rout in the 2018 elections. The current Progressive Conservative provincial government tore up the still-outstanding wind turbine construction contracts, says Hunt.
Importing power from neighboring provinces isn’t an option, Hunt says. Purchasing power from electricity-rich Quebec would put Ontario in competition with New England and New York State and drive up electricity rates further. Quebec’s transmission system was built to export power to the US, so new transmission lines would be required to accommodate interprovincial flow, Hunt says. A further complication is that Quebec’s electricity grid is out of phase with the rest of North America’s: The peaks and valleys of its alternating current flow are asynchronous with the rest of the continent’s. As a result, the power imported by Ontario would need to be converted to DC and then converted back to in-phase AC once across the border.
Hunt believes that no more CANDUs will be built in Canada; he sees the future belonging to SMRs. (See Physics Today, December 2018, page 26.) Though SNC-Lavalin has a large SMR design (see the figure on page 23), Fox believes that large reactors will be needed to replace the 2400 MW that Pickering’s CANDUs now supply. Because the entirety of Canada’s nuclear experience with large reactors has been with CANDUs, Fox is confident that the same technology will be chosen if new conventional-size reactors are ordered.
Smaller SMRs could be ideal for providing electricity to remote off-grid communities in the vast Canadian north. The diesel-generated power they use now is expensive, dirty, and vulnerable to cutoffs of fuel supply during severe winter weather. SMRs also would be an attractive option to provide power to remote mining operations and to produce the steam used in extracting oil from Canadian tar sands, Barrett says. Several 300-MW-sized SMRs could meet Saskatchewan’s needs, he notes.
Compared with the US, Canada has made far more progress on the disposition of nuclear waste. The federal Nuclear Waste Management Organization expects to select the location for a geological nuclear waste repository in 2023. Unlike the US, where the now-abandoned Yucca Mountain location was unsuccessfully forced on Nevada, the waste authority invited site proposals from communities; 22 were received. After each was characterized, two Ontario sites were named finalists: one in farmland about 45 kilometers east of Lake Huron and the other in the exposed rock of the Canadian Shield about 246 kilometers northwest of Thunder Bay.
© 2021 American Institute of Physics.
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