<P> 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). </P> <P> 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 . Many SLOWPOKEs are still in use in Canada; one has been running at École Polytechnique de Montréal since 1976, for instance . </P> <P> 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 NPD started operation in June 1962 and demonstrated the unique concepts of on - power refueling 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 . </P> <P> 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 . 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 . </P>

When was the first nuclear power plant built in canada