Temperature Coefficient and Conversion Ratio Analysis on Proposed Modified Core Model Traveling Wave Reactor Prototype

TerraPower Traveling Wave Reactor-Prototype (TWR-P) provides the potential to properly address depleted uranium waste problems through an improved uranium utilization system. Despite all the economic and environmental benefits, the concept is shrouded with criticism against its use of sodium as the coolant due to the experience of sodium leaks and its unwary design to enrichment. The sodium-cooled fast reactor has a checkered history, with accidents such as Superphenix (France) and Monju (Japan). This is because sodium characteristic that burns on contact with air and reacts violently with water when leaks occurred in the reactor. Such an accident is often followed by expensive processes of cleanup, testing, and inspection before the reactor able to be restarted. Thus, the paper pursues an alternative to sodium, by looking at the temperature coefficient, initial multiplication factor, and conversion ratio. In addition to that, the paper further discusses possible loading pattern modifications to improve the above parameter to compensate for the coolant change. Neutronic analysis of the core has been conducted utilizing Monte Carlo N-Particle simulation. The analysis specifically focuses on altering the coolant of the reactor and the fuel loading pattern, to investigate the shift in the initial multiplication factor, temperature coefficient, and conversion ratio. The adjustment on the coolant from sodium to lead-bismuth eutectics resulted in an increase of initial multiplication factor from 1.06750 to 1.10959 respectively with 15% enrichment of uranium. Improvements are found similarly by replacing the benchmark model to the second loading pattern in terms of its initial multiplication factor from 1.10959 to 1.14879, and temperature coefficient from -0.2017 to -0.2312. On the contrary, the decrease in conversion ratio can also be observed from 0.838 to 0.738.