Going Nuclear in Canada (Includes Rare Photos of Chalk River Laboratories)
What comes to mind when you hear the word “nuclear?” Many remember hiding under school desks as nuclear conflict loomed during the Cold War. Today, we might think of North Korea, which has been testing nuclear weapons since 2006.
But in Canada, "nuclear" can also evoke the peaceful development of nuclear technology. This history dates back to the beginnings of nuclear science and includes Chalk River Laboratories in Chalk River, Ontario. This research facility helped develop Canada’s world-class Canada Deuterium Uranium (CANDU) reactors.
Below is a brief history of the beginnings of nuclear science in Canada, a story filled with unexpected events — including a daring escape — as well as several rare photos from our Digital Archive Ontario.
Origins in Canada
In 1900, McGill University (Montreal, Quebec) hired the famed New Zealand-British scientist Ernest Rutherford. At McGill, Rutherford discovered the half-life of radioactive materials. He won the Nobel Prize in 1908 for this work, but he did his most famous work after he accepted a position at the University of Manchester, developing his “Rutherford” model of the atom (the same one found in your Grade 11 science text).
Rutherford's early work attracted dozens of Canadian students to McGill and many graduated in the new field of nuclear physics under his supervision. The legacy he left in the form of a generation of Canadian nuclear physicists was the crucial first step towards Canada’s upcoming role as a leader in nuclear.
Nuclear science developed slowly until it became clear that World War II was on the horizon. By 1937, France, the UK and the USA were investing in research to develop nuclear weapons in anticipation of the conflict with Axis nations. This is where the excitement begins — but first, it’s worth knowing a bit about how the nuclear reactors everyone in the war desperately wanted actually worked.
How Nuclear Works
Thanks to the research pioneered by Rutherford and carried on by scientists like the Canadians he trained in Montreal, it was theorized that a machine could be built to harness a very powerful type of energy produced by splitting atoms. The energy generated by this process would be orders of magnitude more than what could be created through traditional combustion, like with dynamite.
The process of splitting atoms is called nuclear fission. This is when the nucleus of a heavy atomic particle like uranium or plutonium is split in two, resulting in a massive release of energy along with an excess of neutrons and radioactive waste. The extra neutrons can trigger more atoms to split, causing a chain reaction. Creating a sustained chain reaction is what allows today’s nuclear reactors to produce a continuous source of energy.
However, in order for this reaction to remain controlled a mediator fluid must be used, and this was a problem for scientists in the 1930’s. Water was considered to be the best option but was still not quite right for the technology of the day. Check out the Canadian Nuclear Association's in-depth explanation of nuclear fission.
A breakthrough came when scientists in Paris identified a moderator that would work for nuclear reactors: heavy water. Unfortunately, the only known source of heavy water in the world was a 180 kilogram stockpile in Norway, produced by a fertilizer company. The French scientists had to find a way to transport the water to France while eluding Germany, who had launched their own nuclear weapons program the day the war broke out.
The race to build the first nuclear weapons was close in the early years of the war. The Nazis had several famous scientists directed towards this effort, including the Nobel Laureate and pioneer of quantum mechanics Werner Heisenberg. They were aware of what was required to build a reactor and they wanted the heavy water.
A Daring Escape and Canada's Wartime Role
In 1940, a French plane was deployed to Norway to purchase the heavy water. On the way back, the plane was intercepted and captured by German planes sent to take it for themselves. But they found the cargo was empty — France had used the plane as a decoy while the real mission was conducted undercover and the water made it safely back to France. France was briefly the most likely nation in the world to win the nuclear arms race.
But France began to fall to German invasion that same year. In an effort to keep the heavy water away from the Nazis, France sent it to Cambridge, England for the English to continue the research. Because England's research capabilities were limited by the conditions of the war, a partnership with the United States was seen as the only viable route to continue nuclear development.
Canada was the perfect mediator between the United Kingdom and the United States, given Canada's uranium stash uncovered at Great Bear Lake in 1930, its available nuclear physicists and its favourable political position. Canada then found itself in the unlikely position of being poised to take the lead internationally in nuclear development.
In 1942, the heavy water and the researchers from Cambridge were sent to Montreal to form a new working group. Here, they laid the plans for the new NRX (National Research Experimental) reactor. A test reactor pile called ZEEP (Zero Energy Experimental Pile), a precursor to the NRX reactor, would become one of the first to operate anywhere in the world — the first reactor had been tested that year in Chicago — and it would be located in a small town called Chalk River.
Chalk River Laboratories
Chalk River is located in the Upper Ottawa Valley, part of the municipality of Laurentian Hills in Renfrew County. It sits about ten kilometres west of the Ottawa River. As a rural village that reported 1029 people in 2016, you could walk the length of the town in 15 minutes. But a 25-minute drive towards the Ottawa River will take you to the site of the first nuclear reactor to operate outside of the United States: Chalk River Laboratories.
The name Chalk River is said to have arisen from 19th-century loggers sending chalk-marked logs down the Ottawa River. Toronto Public Library has digitized many historical photos of the Chalk River Laboratories from our Toronto Star Photograph Archive.
It was determined that the method involving heavy water would not yield nuclear weapons before the end of the war, so Chalk River Laboratories were tasked with exploring the original purpose of nuclear reactors: providing energy. Canada cannot claim to have played no part in the development of atomic bombs that were unleashed upon the Japanese population in 1945, however, because the uranium mined from Great Bear Lake was sent to the USA for refinement and used to develop the bombs.
While the United States found ways to bypass the need for the heavy water and develop nuclear arms, Canada set to work on energy production. By the late 1950s, the research conducted at Chalk River had yielded the CANDU reactor design found around the world today. Because these reactors can use both enriched and unenriched uranium as fuel, they are able to convert decommissioned nuclear weapons into fuel sources, reducing the global nuclear arsenal. Most existing reactors are in Ontario, but some have been exported to Argentina, China, India, Pakistan, Romania and South Korea.
Along with energy production, a new use for nuclear materials was discovered in the 1940s. Since 1947, the Chalk River reactors have provided as much as 40% of the world’s supply of medical isotopes. These materials are used primarily in the diagnosis and treatment of cancer. The NRU (National Research Universal) reactor, built in 1957, put Chalk River and the Canadian government under international scrutiny when it was shut down for a year in 2009, creating a worldwide shortage of medical isotopes. Over the course of its life, the facility produced enough isotopes to save millions of lives.
Although nuclear power is the cleanest and most efficient method of energy production, it also poses great environmental risks. The NRX reactor in Chalk River holds the distinction of having the world’s first meltdown of a nuclear reactor. In 1952, a loss of coolant caused uranium rods to overheat. This resulted in a massive hydrogen explosion and the leakage of tonnes of radioactive water. Future president Jimmy Carter took part in the clean up operation as a U.S. Navy officer.
The NRX reactor went back into commission two years later, but then in 1958 the NRU reactor experienced a fuel rupture which caused a fire outbreak and massive contamination of the area. Currently, there are tens of thousands of spent fuel rods that must be processed and deposited into safe burial sites deep underground.
Earthquakes still pose a risk of environmental contamination if these tombs were to rupture. Some radioactive waste takes hundreds of thousands of years to decay — and there is currently no fail-safe method of disposing it. In spite of this, nuclear energy presents an alternative to the fast-acting dangers of fossil fuels.
CANDU reactors were the direct result of the research conducted at the Chalk River facilities. Although the main NRU reactor was decommissioned in 2016, the government pledged new funding for Chalk River Laboratories to develop the next generation of reactors. These could produce better medical isotopes, use hydrogen as a clean fuel source and might even become so small and safe that they could be portable.
Today, nuclear reactors at five different plants generate 15% of Canada’s and 60% of Ontario's electricity. As of 2015, CANDU had provided 23.16 GWe (gigawatt electrical) through 47 reactors worldwide.
- Chalk River and Chalk River Laboratories (Digital Archive Ontario)
- Nuclear science in Ontario (Digital Archive Ontario)
- Nuclear science in Canada (Library and Archives Canada)
- Camera Atomica (Art Gallery of Ontario exhibit)
- Nuclear science in the United States (American National Archives)
- Uranium and Nuclear Power Facts (Natural Resources Canada)
- Nuclear Power Plants (Canadian Nuclear Safety Commission)
- Nuclear power in Ontario today (Ontario Power Generation)
- Canada Enters the Nuclear Age: A Technical History of Atomic Energy of Canada Limited
- Nuclear Power: In Canada and Beyond
- Deep Waters: The Ottawa River and Canada's Nuclear Adventure
- Disarming Doomsday: The Human Impact of Nuclear Weapons since Hiroshima
- Lines of Flight: An Atomic Memoir
Update: correction made to statement that the ZEEP reactor was the second in the world to operate. (Dec. 16, 2022)