Thermal Design of the TREAT Facility

The Transient Reactor Test (TREAT) Facility is a graphite reactor capable of delivering tailored power histories to unique experiment designs. Frequently, these experiments are designed to simulate a specific reactor transient to perform detailed studies of reactor fuel behavior. The reactor core is uniquely designed to allow a limited energy release and resulting peak fuel cladding temperature such that thermal feedback mechanisms shut the reactor power transient down in a passive manner, thus maximizing the lifetime of the reactor fuel cladding. The reactor is air cooled; however, the cooling system does not serve a safety function. The air cooling is typically used for four main functions: (1) accelerate cooling of the reactor core to ambient temperature post transient operations, (2) remove activated gases from the reactor cavity, (3) perform heat balance for power calibration, and (4) maintain criticality on extended steady-state runs or shaped transients. With the restart of the reactor, these systems are now fully operational and have been exercised during the past year for the first time in more than 20 years. This paper summarizes the thermal properties of the core and the thermal-hydraulic design of the TREAT Facility and presents selected results of temperature profiles resulting from operation. Conservatively estimated maximum transient energy and steady-state power is provided.