CODE-TO-CODE BENCHMARK STUDY FOR THERMAL STRESS MODELING AND PRELIMINARY ANALYSIS OF THE HIGH-TEMPERATURE SINGLE HEAT PIPE EXPERIMENT

In the heat-pipe-cooled microreactor, heat pipes remove heat from the reactor core as a passive heat-transfer
device, so the fluid circulation is not required for cooling, which can substantially simplify the overall
reactor design. However, given the extremely high temperatures in the core region and potentially large
temperature gradients across the structure materials, thermal stresses need to be well-analyzed to ensure
structural integrity during normal operations and accident scenarios.
This paper discusses finite element method-based thermal-stress analysis for the high-temperature single
heat-pipe test article in the Single Primary Heat Extraction and Removal Emulator (SPHERE) facility at
Idaho National Laboratory (INL), using two commercial software packages, Abaqus and Star-CCM+. A
code-to-code benchmark study was performed to crosscheck the model setup and capability of each code
and to gain preliminary insights into the potential thermal stress concerns from the current experimental
setup. It is observed the significant thermal stresses happen at the inner surface of the heat pipe hole
surrounded by electric heaters where the largest temperature gradients appear. The temperature fields have
good agreements between Abaqus and Star-CCM+, while the induced thermal stresses show modest
deviations probably due to differences of meshing engines used in these two codes. It is found that the local
maximum thermal stresses may reach close to the ultimate tensile strength and yield strength of structural
material depending on the heater power. Ultimately, the coupled thermal-structural analysis will help guide
the current experimental plan and ensure the facility safety for future experimental study