An absorber rod for a nuclear reactor having a rod cladding defining an internal volume, the rod cladding having an upper end and a lower end, an upper end fitting positioned in the upper end of the rod cladding, a rod internal arrangement configured in the internal volume of the rod cladding, an absorber rod lower end cap positioned at the lower end of the rod cladding, the lower end cap having an upper surface and a lower surface, a stack support with a stack support upper end and a stack support lower end, the stack support lower end placed in contact with the upper surface of the lower end cap, the stack support upper end configured to support the rod internal arrangement, and an annulus of material configured around the stack support and contacting the upper surface of the lower end cap.