Thermal Design Summary for FCM Rabbits

Abstract

The FCM rabbit experiments are designed to irradiate prototypically-sized light water reactor (LWR) fuel pellets that are comprised of a matrix material (SiC or a Zirconium alloy) with coated particles embedded within. The coated particles are standard TRISO kernels that may contain a surrogate (ZrO2) core material or actual fuel material. Five pellets are stacked within the rabbit with graphite spacers between pellets. The pellet stack is contained within a Zirconium-alloy cladding. A design temperature of 400°C is specified at the pellet/cladding interface. The primary outer containment is an Al-6061 tube with an outer diameter of 10.96 mm (0.432"). The specimen temperature is controlled by the axial location, fill gas, the size of the gap between the cladding and housing, and the coated particle loading. Helium is used as the fill gas inside the experiments. This letter report documents the overall design and the analyses performed to design two surrogate and two fueled rabbits.