A new code, the Fuel Engineering and Structural analysis Tool (FEAST), was developed to predict the performance of metal and oxide fuel in sodium-cooled fast reactors. FEAST describes key irradiation phenomena and can analyze the fuel and clad thermo-mechanical behavior at both steady-state and design-basis transients. FEAST has been coupled to the coolant subchannel analysis code COBRA, to improve the accuracy of temperature predictions in a fuel assembly. t was used to support fuel design in the Terrapower reactor.
Innovative fuel concepts were compared to the traditional cylindrical geometry. The annular fuel concept, with internal and external cooling, was found best suited for low-conversion metal-fuelled cores, where it can enable a power uprate of ~20%; limited by the fuel clad chemical interaction upon a hypothetical blockage of the inner-annular channel. The bottle-shaped fuel concept was found best suited for tight high-conversion ratio cores, where it can reduce the overall core pressure drop by >30%, with a corresponding increase in core height between 15 and 18%.