Abstract: A fuel assembly (16) for a nuclear reactor contains fuel rods (48) which contain nuclear fuel pellets (62) held in place by a spring means or a like device (64) and end plugs (56,58) where a hollow gas absorber structure (80) is also disposed within the fuel rods (48) where at least one surface of the absorber structure (80) is coated with a catalyst material (83) that absorbs and retains at least one of hydrogen and tritium.

Abstract: An advanced gray rod control assembly (GRCA) is for a nuclear reactor. The reactor has a plurality of fuel assemblies each including numerous elongated fuel rods supported in an organized array by substantially transverse support grids, and a plurality of guide thimbles disposed through the support grids and along the fuel rods. The GRCA includes a spider assembly structured to provide controlled insertion of gray rod assemblies within the thimbles of the fuel assembly, thereby controlling the rate of power produced by the reactor. Each gray rod assembly includes an elongated tubular member, a first end plug, a second end plug, a substantially pure silver neutron-absorber disposed within the tubular member, and a support tube surrounding the neutron-absorber within the tubular member to resist silver-swelling. Delta-power of the reactor is improved by minimizing the exposed surface area of the absorber and distributing it among all of the rods of the GRCA.