Performance Analysis of Silicon Carbide Composite Clad Uranium Carbide Fuel for a Long-Life Gas-Cooled Fast Reactor Under Normal Operation-Part I: Design Criteria and Material Data

Fuel performance analysis was conducted for the silicon carbide (SiC) composite clad uranium carbide (UC) fuel of a 500-MW(thermal) gas-cooled fast reactor, specifically the energy multiplier module (EM2) under normal operation. The analysis consists of two parts: Part I (this paper) includes a description of design bases and criteria, fuel element design specifications, and material properties and models, while Part II includes the fuel modeling approach, computer code, and fuel design evaluation. In Part I, the design bases and criteria describe the maximum allowed material temperature, cladding stress limit for structural integrity, and cladding strain limit for hermeticity. The material properties and models have been collected from open literature and recent measurements for the UC and SiC composites, respectively. As a result of reviewing legacy UC properties and models, it is recommended to measure the as-fabricated EM2 fuel properties with high priority to the thermal conductivity, swelling rate, and mechanical strength. For the SiC composite cladding, it is recommended to refine the creep rate for its temperature and time dependence. The stress-strain model also needs to be refined for its strain rate, irradiation, and temperature dependence.