A fuel pebble for use in a fusion-fission engine includes a buffer material and a fertile or fissile fuel shell surrounding the buffer material. The fuel pebble also includes a containment shell surrounding the fertile or fissile fuel shell. The containment shell includes silicon carbide. The fuel pebble further includes a composite material layer surrounding the containment shell and a cladding layer surrounding the composite material layer.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH OR 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.