The Spallation Neutron Source (SNS) is an accelerator-based neutron source at Oak Ridge National Laboratory (ORNL). The SNS facility provides the most intense pulsed neutron beams in the world for scientific research and industrial development.
The liquid mercury target, moderators and beryllium reflectors are contained inside the inner reflector plug. The main objectives of the redesign of the inner reflector plug are simplifying its disposal and increasing its neutronic performance. The inner reflector plug is actively cooled by flowing heavy and light water through a maze of channels. Recent advancements in capacity for large scale Computational Fluid Dynamics modeling via the high performance compute systems of ORNL now enable high-fidelity simulation approaching full geometric scale.
Accordingly, in this study, three dimensional conjugate heat transfer simulations of the inner reflector plug were carried out with STAR-CCM+ v7. The volumetric heating rates from Monte Carlo calculations in the various components of the inner reflector plug at 2 MW proton beam power were used in simulations. Thermal hydraulic results show that the maximum temperatures occurring in the components of the next generation inner reflector plug meet the thermal design criteria.