Canadian deuterium uranium reactor
Canadian deuterium uranium reactor (CANDU) is a pressurized heavy water nuclear reactor using deuterium oxide (D2O), rather than light water (H2O), as the coolant and moderator. In a deuterium-moderated-reactor, fuel made from natural uranium (0.71 U-235) can sustain a chain reaction. The CANDU reactor core also allows of on-power refueling, which makes for greater efficiency.
CANDU was developed by the Atomic Energy of Canada (AECL) along with the electrical utility of Ontario, and private industry including GE Canada. All of the current nuclear reactors in Canada are of the CANDU Design, including 20 in Ontario, 1 in New Brunswick and one in Quebec. 12 CANDU reactors have also sold and are in use around the world. AECL is still trying to sell more CANDU reactors both in Canada and around the world.