Radial power distribution of PWR cores is less dependent on relative power. The number and depth of inserted rod cluster control assemblies are small and therefore the effect of control rods is small and the burnup effect is also mild. For flattening of the core radial power distribution, it is, therefore, sufficient only to properly locate fuel assemblies and burnable poisons in the core design. The core radial power distribution is just monitored during reactor operation and adjustment by control rods is not needed. A specific arrangement of fuel assemblies is shown in Fig. 3.47 (gadolinia-added fuel assemblies are used, and no burnable poison rods in this example) and its corresponding radial power distributions are shown in Fig. 3.48 (BOC) and Fig. 3.49 (EOC). The radial power distribution is represented as the relative value of fuel assembly power to core-averaged fuel assembly power for the symmetric octant core. Comparison between the radial power distributions at BOC and EOC indicates that gadolinia-added fresh fuel assemblies and neighboring fuel assemblies give a relatively large increase in power, but the variation in power is mild as burnup progresses.