Abstract: A neutron flux control component for a nuclear reactor. Thin, overlapping segments of highly neutron absorbing material are positioned in the core of a reactor. The self-shielding overlapping segments are moved relative to each other to vary the amount of exposed surface area of poison to control core reactivity and to provide power shaping within the reactor core. The poison segments are mounted to carriers in the form of close-fitting concentric cylinders or rods of V-shaped cross section.

Abstract: A particle bed fuel element designed to accommodate expansion and contraction within the particle fuel bed. Porous inner and outer frits connected together by an end cap at a first end and radially guided by a shoulder at a second end receive fuel particles in the annulus formed therebetween. Compressive devices at each end of the frits and within the fuel bed maintain packing force to prevent looseness during contraction and allow expansion without excessive pressure being placed on the fuel particles. Pairs of beleville springs, wave springs, and pressurized thin-walled metal donuts may be used as the compressive devices.

Abstract: A gas cooled nuclear fuel element. A plurality of progressively sized rigid porous cylinders nested together in coaxial alignment are provided with varying quantities of nuclear fuel to enhance the power density while remaining within temperature limitations of the fuel and base material.