The resulting fuel assembly is about the size and form of a practice golf ball and when the fuel assemblies are placed in a ... In normal operation, output coolant temperature is controlled by 14 control rods acting in guide tubes within the core. ... indirect systems are used but one of the more popular employing three heat exchangers is shown in schematic form in Fig. 4. ... As a general guide for up to 14 apartments, Ad/o Total Annual Generation 1Yr Duration Diagram of Applied Heat 301.