CANada Deuterium Uranium

The CANDU, for CANada Deuterium Uranium, is a Canadian-developed, pressurized heavy water reactor used to generate electric power. The acronym refers to its deuterium oxide (heavy water) moderator and its use of (originally, natural) uranium fuel. CANDU reactors were first developed in the late 1950s and 1960s by a partnership between Atomic Energy of Canada Limited (AECL), the Hydro-Electric Power Commission of Ontario, Canadian General Electric, and other companies.

There have been two major types of CANDU reactors, the original design of around 500 MWe that was intended to be used in multi-reactor installations in large plants, and the rationalized CANDU6 in the 600 MWe class that is designed to be used in single stand-alone units or in small multi-unit plants. CANDU6 units were built in Quebec and New Brunswick, as well as Pakistan, Argentina, South Korea, Romania, and China. A single example of a non-CANDU6 design was sold to India. The multi-unit design was used only in Ontario, Canada, and grew in size and power as more units were installed in the province, reaching ~880 MWe in the units installed at the Darlington Nuclear Generating Station. An effort to rationalize the larger units in a fashion similar to CANDU6 led to the CANDU9 effort, but did not achieve any sales.

By the early 2000s, sales prospects for the original CANDU designs were dwindling due to the introduction of newer designs from other companies. AECL responded by cancelling CANDU9 and moving to the Advanced CANDU reactor (ACR) design. ACR failed to find any buyers; its last potential sale was to Darlington, but this expansion was cancelled in 2009. In October 2011, the Canadian Federal Government licensed the CANDU design to Candu Energy (a wholly owned subsidiary of SNC-Lavalin), which also acquired the former reactor development and marketing division of AECL at that time. Candu Energy offers support services for existing sites, and are completing formerly stalled installations in Romania and Argentina through a partnership with China National Nuclear Corporation. Further design and new sales efforts have ended.

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