Sockeye Validation Support Using the SPHERE Facility

The engineering-scale heat pipe application Sockeye, being developed through the U.S. DOE Nuclear Energy Advanced Modeling and Simulation (NEAMS) program, is concurrently undergoing code development and verification and validation a ctivities. One such validation activity is part of a larger collaboration between the NEAMS program and the U.S. DOE MicroReactor Program (MRP). This activity involves using Sockeye to model one of the numerous sodium heat pipe experiments from the MRP's Single Primary Heat Extraction and Removal Emulator (SPHERE) facility at Idaho National Laboratory for validation purposes. Heat pipe data produced by the SPHERE facility was used to create a useful validation case for Sockeye. Sockeye's conduction model was used to simulate an experimental run at SPHERE. The steady-state temperature distribution was accurately reproduced, but discrepancies with experimental data were found in the transient behavior after the power shutoff. This effort also revealed a number of challenges of modeling an experimental setup such as SPHERE. For example, the simulation results are strongly dependent on many experimental parameters that were not described or characterized at the time, such as possible gaps in insulation.