“…Such particles typically include a distribution of approximately 15% open porosity to act as a fission gas 'plenum' reducing the gas-driven pressure on the matrix. Dispersions using this concept have been proven to work well in combination with ductile matrices such as steel [10] and niobium [11]; performance has been postulated to be limited by a combination of fission density and temperature [12]. Analysis of GFR fuel requirements, however, eliminates metal alloys from consideration (see below).…”