The GFR (Gas cooled Fast Reactor) combines the advantages of a fast neutron spectrum with those of high temperatures. Given the high core outlet temperatures exceeding 800 C, it is clear that conventional metallic core structures and fuel cladding will be unable to meet the demanding requirements. Thus, only refractory metals or ceramic components can be considered for these purposes, as temperature excursions above 1600 C have to be foreseen. The design and development of an innovative refractory fuel in an advanced ceramic cladding remains a fundamental goal of the GFR system. Today, the focus is on SiC composite as structural and cladding material, with carbide (MC) fuel taking first priority over both oxide and nitride fuels as backups. Compatibility tests have shown that SiC and mixed metal carbide fuels (MC) react, necessitating the introduction of a protective liner made of W or other refractory material. 2 fuel element design option are considered: the plate type fuel and the pin type fuel. The basic design of plate type fuel is based on two ceramic plates, which enclose a honeycomb structure containing cylindrical pellets made of the mixed carbide fuel. Pin type fuel will be similar to current fast reactor designs