Core Power Flattening Studies Supporting Narrowing Transient Pulse Widths in TREAT

摘要

The Transient Reactor Test (TREAT) Facility was constructed in the late 1950's and operated until 1994, at which time it was placed in standby after providing thousands of transient irradiations . This facility was restarted in late 2017 and has been undergoing restart testing and core characterization activities, in preparation to provide once again transient testing capabilities for modern experimental needs. TREAT is an air-cooled reactor comprising graphite fuel blocks with dispersed uranium oxide fuel encapsulated in zirconium alloy canisters with an active core length of ~1.2 m. Aluminum-sheathed graphite blocks provide a ~61 cm reflector surrounding the 19×19 grid of interchangeable fueled and nonfueled assemblies. A few fuel assemblies are typically removed from the central core positions to create a cavity for experiments. A more comprehensive description of TREAT can be found elsewhere . Transient testing is the study of nuclear fuels and materials under events of instantaneous changes in conditions such as postulated off-normal, accidental, or upset conditions in nuclear plants. In-pile nuclear-heated transient testing is required to more accurately provide rapid power excursions, representative heat generation, and coupled irradiation effects. TREAT was designed to provide a comprehensive nuclear transient testing environment.