Every nuclear generating station in Canada uses CANDU (CANada Deuterium Uranium) reactors, which are based on technology designed and developed in Canada. Gentilly-2 is equipped with a CANDU-PHW reactor that uses pressurized heavy water as a reactor coolant and a moderator.
CANDU reactors offer many advantages. From a safety perspective, they have multiple containment barriers. Fuel supply is readily available, and the reactors can be refueled while online. Gentilly-2 and stations like it are designed, built, maintained and operated to guarantee maximum safety. The probability of a failure, defect or accident is extremely low.
CANDU reactors are fueled with natural uranium. The fuel used at Gentilly-2 is Canadian-mined and consists primarily of uranium-238 (99.3%) with a small amount of uranium-235 (0.7%). Only uranium-235 nuclei are fissionable.
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The chemical composition of heavy water is almost identical to that of ordinary water (H2O). However, its hydrogen atoms are heavy isotopes (deuterium) whose nuclei contain a neutron in addition to the proton found in every hydrogen atom.
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