A study on improvement of sodium cooled TRU burner design using burnable poison

A new design approach to improve safety characteristics of sodium cooled core for transuranic element transmutation is discussed. In the new option, some amount of fertile material is removed for reduction of sodium void reactivity. Simultaneously, a burnable absorber material is loaded in replacement of fertile material to compensate for reactivity drop during the fuel depletion. Two methods of burnable absorber loading are considered such as the homogeneous and the heterogeneous. In the results, it is found that the homogeneous loading cannot reduce the sodium void reactivity but makes the reactivity more positive. On the other hand, the heterogeneous loading can reduce the sodium void reactivity successfully. It is also found that the increment in burnup reactivity swing is negligible when the burnable poison is heterogeneously loaded. It is concluded that if the burnable poison material is loaded appropriately, the sodium void reactivity can be reduced without any significant penalty of increase in burnup reactivity swing.