Nuclear Energy

Nuclear power plants use uranium to generate heat and boil water into steam. Uranium has the largest atoms of the 92 naturally-occurring elements on earth, and therefore have the greatest likelihood of splitting.

CANDU fuel bundle
One of these half-metre nuclear fuel bundles can provide enough electricity to power 100 homes for a year.

When subatomic particles called neutrons come into contact with uranium atoms, the atoms split, releasing heat energy. This occurs all the time in nature, but at a very slow rate. Nuclear reactors are able to greatly speed up this process by slowing down the neutrons and increasing the likelihood that they will hit and split the uranium atoms. When uranium atoms split they also release more neutrons which can then go on and split additional atoms ensuring a chain reaction of atom splitting. This is called nuclear fission. At the heart of every nuclear reactor are fuel pellets no bigger than the tip of your finger. Despite their small size, these fuel pellets hold the potential to produce tremendous amounts of energy.

uranium pellet
One uranium fuel pellet.

Canada’s nuclear reactors use fuel pellets that are made from naturally occurring uranium that is mined in Canada. The pellets are inserted into tubes about half-a-metre in length made from zirconium alloy, a special type of metal that has a high resistance to corrosion. The tubes are welded shut and several are then assembled together into what is called a fuel bundle. One of these half-metre fuel bundles can provide enough electricity to power 100 homes for a year.

Hundreds of fuel bundles are inserted into the core of a nuclear reactor where the uranium atoms split, giving off vast amounts of heat. This heat is used to boil water to create steam, which then spins a turbine and generator producing electricity. Nuclear power stations are able to produce tremendous amounts of electricity from a very small amount of fuel. A single 1.65 cm nuclear fuel pellet can produce the same amount of energy as 400 kilograms of coal, 410 litres of oil, or 350 cubic metres of natural gas. As well, because nuclear power plants do not burn any fuels, they produce virtually no smog or greenhouse gas emissions (GHGs). They do however produce nuclear waste which needs to be handled and stored very carefully.

nuclear power plant
Diagram of a nuclear power plant.

Nuclear Energy Worldwide

In 2010, nuclear energy produced 13% of the world’s electricity. Nuclear became an important source of energy following the first oil price shock in 1973. The main reasons for the rise of nuclear power are the low cost of fuel compared to other primary energy sources and abundant uranium resources located in politically stable regions. Total known recoverable uranium resources equal 5.4 million tonnes, half of which are found in Australia, Kazakhstan, and Canada. Canada is currently the second-largest manufacturer of uranium, producing about 16% in 2012 of the world’s total.

Global Electricity Generation in 2010
Percentage of Total
Fossil Fuels
Solar, Tidal & Wave

France, which gets 77% of its electricity from nuclear power, Lithuania, which gets 64% and Belgium, which gets 54%, rely most heavily on nuclear energy. Fourteen countries rely on nuclear energy to provide more than one-quarter of their electricity supply. The United States has the largest nuclear generating capacity in the world with 104 reactors in operation, generating about 19.4% of the power required by Americans. Here in Canada, about 15% of all the electricity produced comes from nuclear power plants. Ontario’s 16 operating reactors produce 51% of that province’s electricity.

If not for major incidents in world history, nuclear power might have grown exponentially until now. Chernobyl, Three Mile Island and Fukushima are three events that have left a significant impact in nuclear history. Due to the serious nature of these events, public attitudes have been affected toward nuclear power.

Nuclear power is highly regulated in Canada. Members of the Canadian Nuclear Safety Commission (CNSC) use the Nuclear Safety and Control Act to make decisions and write policies concerning nuclear energy, materials and equipment. The regulations enforced by the CNSC are to protect the safety, security and health of Canadians and apply to all nuclear activities (mining, refining, spent fuel, etc.). Hospitals and clinics that use radioisotopes in various medical procedures also fall into this domain.

Globally, 12 CANDU units are operating in six countries outside Canada. Domestically we are home to 19 operating CANDU reactors.


Ontario Power Generation,
World Nuclear Association,