ABSTRACT
In the 1950s and 1960s, heavy water reactor (HWR) technology was explored in most of the countries investigating the application of nuclear fission to energy production. However, it was in Canada that this line of reactors was initially selected as the preferred type, which would become known as CANada Deuterium Uranium (CANDU). The choice was influenced by the early development work in Canada within the Manhattan Project, which took advantage of the superior characteristics of heavy water moderation for the production of plutonium. The attraction for ongoing development was mostly in the comparative simplicity of a system that did not depend on isotopic enrichment of uranium for the fuel. Further simplicity was introduced with the choice of pressure tubes (rather than a pressure vessel) to contain the operating pressure. The use of natural uranium and of pressure tubes make CANDU technology relatively easily accessible. Fuel manufacture has been successfully developed virtually everywhere where CANDUs have been built, and the dependence on very specialized large component fabricators to produce pressure vessels has been avoided.
