The CANDU reactor consumes natural uranium, using nuclear-purity heavy water (isotopic content above 99.75% D2O) as moderator and coolant, in two independent, separate, closed-circuit systems.
In the 4 steam generators, heat from the primary circuit is taken over by the light water from the secondary circuit, by transforming it into saturated steam. It expands in the turbine formed by a medium-pressure body and 3 low-pressure bodies, producing the mechanical energy required to operate the electric generator.
At the exit from the turbine, by extracting the residual heat with the help of cooling water taken from the Danube, the steam is condensed. The circuit is restarted by repumping the condensate to feed the steam generators.