Transient Reactor Test (TREAT) Facility Design and Experiment Capability

The Transient Reactor Test (TREAT) facility was designed and built in the late 1950s. The air-cooled reactor design incorporates fuel composed of highly enriched uranium dispersed in graphite with a 10 000:1 carbon-to-uranium atom ratio to provide a very fast-acting highly negative temperature coefficient of reactivity. The reactor utilizes a forced-air-cooling system for decay heat removal, with a primary function of reducing the time at temperature (oxidation) of the reactor fuel cladding. The simple design with lack of a cooling system pressure boundary provides relatively easy access for instrumentation and experiments. The large thermal mass of the reactor and the simple design allow for high-power transients approaching 18 000 MW in an inherently safe manner. The simple design has allowed TREAT to operate successfully for 35 years before being placed in standby in 1994 and subsequently restarted in 2017 after more than 20 years of standby to continue the transient fuel testing mission in the United States. This technical note addresses the reactor design and experiment capabilities.