Fuel elements with fissile core inside inner and outer sleeves - - which have concave and convex profiles for easy stacking

Reactor fuel element in which the fissile core of particles pressed in a graphite matrix is integrally formed with an inner and outer, pref. graphite sleeve in a high-pressure high temp. pressing operation. The sleeve profiles are convex and concave respectively and facilitate fuel element stacking orientation and core stability against vibration and shock. The fissile cores being continuous throughout the length of the element and also continuous when stacked promoting even flux distribution.