CANDU - PHWR - Pressurized Heavy Water Reactor

PHWRs have been promoted primarily in Canada and India, with additional commercial reactors operating in South Korea, China, Romania, Pakistan, and Argentina. Canadian-designed PHWRs are often called "CANDU" reactors.9 Siemens, ABB (now part of Westinghouse), and Indian firms have also built commercial PHWR reactors. Commercial heavy water reactors now in operation use heavy water as moderators and coolants. No successful effort has been made to license PHWRs in the United States. PHWRs have proven to be popular in several countries because they use less expensive natural (not enriched) uranium fuels and can be built and operated at competitive costs. PHWRs have often been preferred by nations wishing to develop an indigenous fuel cycle without expensive enrichment facilities. The continuous process of refueling PHWRs have raised some proliferation concerns as has the high Pu-239 content of the spent fuel. PHWRs, like most reactors, can use fuels other than uranium. Particular interest has been shown in thorium-based fuel cycles.