Final answer:
The Canadian-made nuclear fission reactors are called CANDU reactors, utilizing heavy water to slow down neutrons and capable of using natural uranium as fuel.
Step-by-step explanation:
The Canadian-made nuclear fission reactors are known as CANDU reactors, which stands for CANada Deuterium Uranium. These are a type of nuclear reactor that use heavy water (deuterium oxide) as a moderator to slow down neutrons in the fission process. CANDU reactors can use natural uranium as fuel due to the use of heavy water, which is more effective at slowing neutrons than ordinary water. This is a unique characteristic of CANDU technology, distinguishing it from other water-cooled reactors that typically require enriched uranium.