Heat generated by fission products would initially be at about 7% of full reactor power, which requires significant cooling. The CANDU designs have several emergency cooling systems, as well as having limited self-pumping capability through thermal means (the steam generator is well above the reactor). Even in the event of a catastrophic accident and core meltdown, the fuel is not critical in light water. This means that cooling the core with water from nearby sources will not add to the reactivity of the fuel mass.
Heat generated by fission products would initially be at about 7% of full reactor power which requires significant cooling The CANDU designs have several emergency cooling systems as well as having limited self-pumping capability through thermal means (the steam generator is well above the reactor) Even in the event of a catastrophic accident and core meltdown the fuel is not critical in light water This means that cooling the core with water from nearby sources will not add to the reactivity of the fuel mass