Study on Fuel Selection for a Long-Life Small Lead-Based Reactor

The choice of an appropriate fuel can effectively prolong the refueling cycle of a reactor core. The Th-U cycle and U-Pu cycle are commonly used fuel breeding cycles. Oxide fuels, nitride fuels, and metal fuels are the primary candidate fuels for lead-based reactors. For fuel selection, a core model of a 60 MWt reactor was established. The results show that the breeding performance of the breeding fuel Th-232 is better than that of U-238, and the driving performance of the driving fuel Pu-239 is better than that of U-235. Therefore, PuO2-ThO2, PuN-ThN, and Pu-Th-Zr fuels may have good performance. By comparing the reactivity loss of three types of fuel, it was found that the reactivity loss of PuN-ThN fuel is the smallest. Hence, using PuN-ThN fuel as a core fuel can result in a longer refueling cycle. On this basis, PuN-ThN fuel was used in the preliminary design of the 120 MWt core physical model. It can be seen that when PuN-ThN fuel is used as the core fuel, a smaller reactivity swing (1408 pcm), smaller power peak factor, and super long refueling cycle (more than 30 years) can be obtained.