Systematic Technology Evaluation Program for SiC/SiC Composite-Based Accident-Tolerant LWR Fuel Cladding and Core Structures

摘要

Fuels and core structures in current light water reactors (LWRs) are vulnerable to catastrophic failure in severe accidents as unfortunately evidenced by the March 2011 Fukushima Dai-ichi Nuclear Power Plant Accident. This vulnerability is attributed primarily to the rapid oxidation kinetics of zirconium alloys in a water vapor environment at very high temperatures. Zr alloys are the primary material in LWR cores except for the fuel itself. Therefore, alternative materials with lower oxidation risks than the zirconium alloys are explored to enable the accident-tolerant fuels and cores. Among the candidate alternative materials for accident-tolerant LWRs, silicon carbide (SiC) based materials, in particular continuous SiC fiber-reinforced SiC matrix ceramic composites (SiC/SiC composites), are considered a leading option that provides outstanding passive safety features in beyond-design basis severe accident scenarios. In addition, they possess other benefits including exceptional radiation resistance that has been demonstrated by extensive neutron irradiation data.