A fuel particle for use in a fusion-fission nuclear engine includes a fuel kernel and a buffer layer surrounding the fuel kernel. The fuel particle also includes a pyrolytic carbon layer surrounding the buffer layer and a silicon carbide layer surrounding the buffer layer. The silicon carbide is characterized by a stress less than 450 MPa at 95% burn-up. The fuel particle further includes a second pyrolytic carbon layer surrounding the silicon carbide layer.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
 The United States Government has rights in this invention pursuant to Contract No. DE-AC52-07NA27344 between the United States Department of Energy and Lawrence Livermore National Security, LLC.