Neutronics and fuel performance analysis of TRISO-based accident tolerant fuel for PWRs

Abstract

South Africa has one nuclear power plant in Cape Town called the Koeberg nuclear power station. This power station still uses conventional uranium dioxide fuel pellets and zirconium cladding. Since the Fukushima-Daiichi nuclear power plant accident, efforts have been made to design alternative nuclear fuel forms in cases of accident conditions. Significant efforts have been made to develop new fuel cladding with different materials to reduce hydrogen production and new fuel pellets that can retain the fission products within the pellet structure (Zinkle et al., 2014). In the Fukushima-Daiichi accident the nuclear core melted, resulting in fission products being released into the environment, thus creating an inhabitable zone. This loss of land was costly, as in Japan land is valuable, as it is in South Africa. A loss of land in South Africa could lead to incalculable consequences for generations. South Africa began designing and manufacturing a Pebble Bed Modular Reactor (PBMR) for commercial use before the project was shelved (Thomas, 2008). Before the project was cancelled, TRISO particle fuel had already been successfully manufactured and tested under irradiation. FCM fuel uses TRISO particles embedded in a SiC matrix instead of the traditional graphite matrix. This study evaluates and compares FCM and UO2 fuel in LWR conditions for neutronics and fuel performance. A simulation is carried out to determine the performance of FCM fuel using the software SERPENT and STACY to compare the performance results of UO2 and FCM fuel. The FCM fuel performance results are compared to experimental results of other TRISO-based fuel experiments, but these are predominantly for gas reactor conditions; thus the comparison is limited. It is noted that FCM fuel performs better than fuel used in the older TRISO-based technologies built for gas reactor conditions; these results diverge from other simulation results where it performs worse than its counterpart when simulated using a SiC matrix.