Abstract: A neutron absorbing panel has improved resistance to loss of efficiency resulting from bending about an axis located at a designated side of the panel. The panel comprises a core of substantially uniform thickness formed of a sintered mixture of particles of neutron absorbing material such as boron carbide (B.sub.4 C) and metal such as aluminum. Metal cladding sheets are provided at both sides of the core, and aluminum is the preferred metal for both the metal core particles, and cladding. The sintered core lacks the ductility of the outer cladding sheets, and to improve bendability, the thickness of one cladding sheet is materially greater than the other. Bending of the improved panel about an axis spaced outwardly from the side thereof having the thinner cladding sheet leaves the outer surface of the panel at the bend smoother than when the cladding sheets are of uniform thickness, and substantially uniform neutron absorbing ability is retained.

Abstract: A method and apparatus for assembling together a rectangular outer tube, a rectangular inner tube and thin flat elongated panels having their side surfaces solidly abutted between the inner wall of the outer tube and the outer wall of the inner tube. The assembly is expanded by applying an internal pressure of at least a thousand psi into contact with a die cavity of rectangular cross-section. In order to minimize the required expansion of the tubes it is desirable that the inner tube conform as closely as possible to the space between the panels prior to expansion. In order to facilitate insertion of the panels, the inner tube is subjected to a controlled collapse in which its sidewalls are curved inwardly and its corners are displaced radially inwardly to provide additional clearance for insertion of the panels. After insertion of the panels the walls of the inner tube are formed outwardly to fit relatively closely within the space defined by the panels.

Abstract: Spline connector for interconnecting adjacent corners of diagonally adjacent rectangular nuclear fuel cell modules are provided with a novel shape including only two attachment arms to permit assembly of a multiplicity of rows of fuel cells while affording access to the edges of the splines for welding them to the storage modules.