High Temperature SiC/SiC CMCs Tailored for Nuclear Environments

New and innovative designs for advanced nuclear power plants, such as General Atomics EM2, require solutions to significant material challenges. Current zirconium alloys and other metals are incapable of being considered as core materials due to increased temperatures and high neutron fluence. Stoichiometric SiC/SiC composites for cladding and other core structures have been identified as the only non-metallic material candidate to allow these new reactor designs to come to fruition. This DOE Phase II SBIR seeks to demonstrate high purity, stoichiometric SiC/SiC CMC components made with commercially available SiC fiber and USAs first low cost, stoichiometric silicon carbide (SiC) ceramic fibers for next generation gas cooled nuclear reactors and the retrofitting of current Gen III LWRs. High purity beta-SiC, from the processes outlined in this proposal, are considered for fuel cladding and in-core structures capable of prolonged operation at temperatures above 1000C in high neutron flux environments, while maintaining strength and chemical inertness over those of alloys, such as Zircaloy. MATECH will produce a number of CMC test articles and conduct rigorous testing and evaluation to qualify high yield, crystalline SiC CMCs. General Atomics (San Diego, CA), for the proposed nuclear applications, and Lockheed Martin Corporation (Palmdale, CA), for non-nuclear aerospace applications, will both be evaluating CMCs produced under this proposed DOE Phase II SBIR program. In Phase I,MATECH fabricated a total of seven distinct SiC/SiC CMC panels by three principal CMC processes, the polymer-impregnation pyrolysis (PIP) process, the chemical vapor infiltration (CVI) process, and a hybrid process of both CVI and PIP. The hybrid manufacturing approach showed the most promise for further development and optimization in the Phase II SBIR program. In Phase II, MATECH proposes a novel Hybrid CVI/PIP CMC processing route, developed and demonstrated in the successful Phase I program, to manufacture high purity stoichiometric SiC CMCs utilizing both commercially available Japanese fiber and MATECHs low-cost SiC-1900X stoichiometric fiber. The goal of this Phase II is to ultimately manufacture test and demonstration panels in the Phase II that are high TRL/MRL. Commercial Applications and Other Benefits: The US currently generates 20% of its electricity from 104 nuclear power plants. This technology can simultaneously reduce Americas reliance on foreign sources of energy and the formation of greenhouse gases. In addition, non-nuclear markets for SiC/SiC CMCs exist in aerospace and defense. The close collaboration with these major industrial stakeholders enhances the likelihood of a successful Phase III transition into commercialization.