Abstract: Bangladesh aims to enhance its nuclear research capabilities through a proposed 10–20 MW multi-purpose research reactor (MPRR) utilizing VVR-KN low-enriched uranium (LEU) fuel, addressing the limitations of its existing 3 MW TRIGA Mark-II reactor, particularly fuel supply constraints. Despite the suitability of VVR-KN fuel for high neutron flux applications, comprehensive studies on its long-term neutronics behavior, including fuel burnup and neutron poison accumulation, remain limited, necessitating detailed analysis for reactor safety and efficiency. This research examines neutronics parameters for a 10 MW MPRR design using OpenMC with critical neutron flux analysis. The objectives include evaluating criticality, neutron flux, power distribution, and fuel depletion. Simulations reveal an effective multiplication factor (keff) of 1.10693 at the beginning of cycle (BOC), closely aligning with reference values, and an average neutron flux of 5.8×1014 neutrons/cm2·s, suitable for isotope production and neutron scattering. Power distribution analysis indicates an average power of 0.283 MW per fuel assembly, with a peaking factor of 1.197, reflecting balanced performance. Over a 90-day cycle, keff reduces to 1.003 due to U-235 loss and neutron absorber buildup (Xe-135, reaches equilibrium after 40-50 hours and, Sm-149, reaches equilibrium after 20 days), with U-238 converting to Pu-239 to sustain reactivity. Reactivity feedback analysis showed a negative fuel temperature coefficient (−2.82 pcm/K) and increasingly negative coolant temperature coefficients, confirming strong inherent safety. These findings validate the VVR-KN fuel’s performance for MPRR applications, providing a robust foundation for safe and efficient reactor design in Bangladesh, with future research recommended for transient reactivity and multi-code validation.

Keywords: VVR-KN fuel, MPRR, Neutronics analysis, OpenMC simulation, Low-enriched uranium

Pages: 119-126

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