Numerical and Experimental Study of Radiative Heat Transfer with Radiation Shielding for Application of Metal Containment Vessel Design in Small Modular Reactor Development

Abstract

Small modular reactors (SMRs) are gaining attention for their safety, low construction costs, and modularity. Many SMRs adopt metal containment vessels (MCVs) for enhanced safety, allowing residual heat removal through the outer wall during accidents. However, the high thermal conductivity of MCVs leads to increased heat loss during normal operation. To address this, creating a vacuum between the Reactor pressure vessel (RPV) and MCV can minimize convective heat transfer but amplifies radiative heat transfer. Preliminary experiments have shown that radiative heat loss accounts for about 60% of total heat loss. Thermal radiation shielding experiments were conducted to reduce radiative heat loss. Two parameters, shielding diameter and material, were chosen for the experiment to show the effect of geometry and emissivity. Experiments were conducted with aluminum (Al) shielding and SS304 shielding to determine the heat loss due to emissivity. Experiments were conducted by changing the shielding diameter to determine the heat loss due to the shielding position between the RPV and MCV. In the main experiment, Al shielding demonstrated a 10% reduction in heat loss compared to SS304, and a smaller shielding diameter resulted in a 3% decrease. The RPV temperature was maintained at 320 ℃, and calculations at steady-state were used to evaluate MCV heat loss to the surroundings. These findings suggest that radiative heat loss should be considered in SMRs with MCV.