[1H13-17] Innovative Reactor

[1H14] Small sodium-cooled RFBB with nitride fuel and LBE Reflectors

*Tsendsuren Amarjargal¹, Jun Nishiyama², Toru Obara¹ (1. Tokyo Institute of Technology, 2. Tokyo City University)

Keywords:RFBB, Nitride fuel and Sodium coolant, Breed-and-Burn Fast Reactor, Lead-Bismuth Reflector

In this work, a Rotational Fuel-shuffling Breed-and-burn fast reactor with nitride fuel and sodium coolant (RFBB-NS) was analyzed. The purpose of the study was to design an RFBB-NS, including assembly duct and control rod assemblies, and to show feasibility. Monte Carlo simulation code Serpent 2.1.0 was used for neutronic and fuel burnup analyses and COMSOL 5.6 Multiphysics was used for heat removal analysis. The results showed that the practical design of RFBB-NS cannot reach criticality due to the presence of neutron-absorbing materials such as assembly ducts. Therefore, the core was modified to increase the neutron economy by applying lead-bismuth reflectors. This allowed the reactor to reach criticality and an equilibrium state after fuel shuffling. Afterward, burnup performance analysis showed that average fuel discharge burnup was around 298 MWd/khHM and, that the Pu concentration in the discharged fuel was lower than in the previous study. However, the radiation damage to the cladding material was slightly higher than the constraint value in this study.