ANALYSIS OF CYCLE LENGTH FOR HIGH-FISSILE-DENSITY FUEL IN HTR-MMR

Abstract

Micro Modular Reactors (MMRs) are gaining significant attention in the nuclear power industry due to their compact design and mobility. However, the challenge of optimizing neutron economy in such reactors remains a critical issue. To address this, advanced fuel designs with higher fissile density are being explored to extend the operational cycle length of MMRs. This paper presents a detailed neutronics simulation of an MMR using High-Fissile-Density Fuel. A High Temperature Reactor (HTR)-based MMR was selected as the reference model. Several case studies involving different High-Fissile-Density Fuel types were conducted, analyzing key neutronic parameters such as cycle length, achievable burnup, power distribution, and nuclide inventory. The simulations also examined the fuel temperature reactivity coefficient to assess the safety and efficiency of the proposed fuels. Thermal power generation and thermal-hydraulic behavior were not considered in this study and are left for future work. Results indicate a significant improvement in cycle length and burnup with the implementation of High-Fissile-Density Fuel, along with a more favorable power distribution. These findings suggest that advanced fuel designs could play a crucial role in enhancing the performance and sustainability of MMRs, contributing to the advancement of small nuclear reactor technologies.