CANDU reactor

The CANDU (Canada deuterium uranium) is a Canadian pressurized heavy-water reactor design 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. It was later exported, and in 2026 there were 26 operational CANDU reactors worldwide: 17 in Canada, three in South Korea, two each in Romania and China, and one each in India and Argentina. 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 optimized CANDU 6 in the 600 MWe class that is designed to be used in single stand-alone units or in small multi-unit plants. CANDU 6 units were built in Quebec and New Brunswick, as well as Pakistan, Argentina, South Korea, Romania, and China. A single example of a non-CANDU 6 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 optimize the larger units in a fashion similar to CANDU 6 led to the CANDU 9. 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 CANDU 9 development and moving to the Advanced CANDU reactor (ACR) design. ACR failed to find any buyers; its last potential sale was for an expansion at Darlington, but this was...