Neutronic design study of a small modular IPWR loaded with accident tolerant-fully ceramic micro-encapsulated (AT-FCM) fuel

Small modular reactors (SMRs) offer a green energy option that will be suitable to serve smaller energy markets with less developed infrastructure. In the present work, a neutronic model of a near term deployable SMR of a natural circulation integral pressurized water reactor (IPWR) design is developed using the TRISO type fuel embedded in SiC matrix. The model development is done using the Monte Carlo Code capable of treating the double heterogeneity in implicit random manner. The Low Enriched Uranium Carbide (LEUC) fuel in TRISO form embedded in SiC matrix and cladded with FeCrAl forms a perfect combination for an accident tolerant fuel for light water reactors due to enhanced capability of fission-product retention of TRISO fuel and lower hydrogen production by FeCrAl at elevated temperature. Length of assembly is altered for reduced active height suitable for SMR application. The depletion analysis is performed for the optimization of fuel enrichment and core loading pattern to achieve a uniform core power distribution. The optimized core is capable of producing 160 MW(th) power with a core life time of more than four EFPYs without refueling or shuffling. The Erbia (Er2O3), 80 w/o enriched in Er-167 as an integral fuel burnable absorber (IFBA) in QUADRISO form, shown excellent depletion performance and control of power peaking throughout the life cycle. This study showed that Doppler, moderator temperature and coolant void reactivity coefficients are all negative over the core lifetime. Transuranic production is low, with relatively higher Pu-240 content in the spent fuel. This leads to a highly proliferation resistant discharge fuel. A new design of RCCA loaded with HfB2 absorber is capable of providing the required shutdown margin in all core conditions. Therefore, the SM-IPWR concept satisfies completely the design criteria and the requirements of an ATF loaded PWR.