Fuel Performance Design Basis for the Versatile Test Reactor

The Fuel Performance Design Basis for the Versatile Test Reactor begins with requirements to maintain safe and efficient reactor operation. For the metal-fueled Versatile Test Reactor, this means a limited number of fuel rod breaches, no fuel melting under steady-state operation and anticipated transients, and continuity of the fuel rod and assembly configuration to avoid impacts to operations of safety systems, maintain expected coolant flow, and allow for efficient fuel handling. Using a large database gathered from previous testing, data were examined to identify and establish preliminary limits on fuel operating conditions. Fuel performance aspects important to fuel operating limits have been identified, including cladding creep, which is addressed with a cladding deformation limit to ensure a limited cladding breach. In addition, fuel-cladding chemical interaction is addressed through limits on cladding temperature and time-at-temperature for steady-state operation, transients, and accidents to mitigate effects leading to cladding breach or fuel melting. Through the implementation of these limits, cladding breach, fuel melting, and deleterious fuel rod and assembly dimensional changes will be prevented.