Patent ID: 8666018

Claim:
An elongated, reactive member for use in a nuclear core comprising: a tubular cladding substantially extending an elongated length of the reactive member; a top end plug sealing off a top end of a central hollow cavity of the tubular cladding; a bottom end plug sealing off a bottom end of the central hollow cavity of the tubular cladding; an active element substantially occupying a lower portion of the central hollow cavity; a spring substantially extending between the top end plug and an upper surface of the active element, pressuring the active element toward the lower end plug; and a spacer between a lower end of the spring and the upper surface of the active element, spreading a force of the spring over a larger portion of the upper surface of the active element than would be applied by the spring directly wherein the spacer has a substantially flat head facing the upper surface of the active element and an opposite side that extends in an axial direction of an elongated dimension of the cladding with the opposite side having a distal portion extending within and being mechanically attached to the spring and a diameter of the distal portion is less than a diameter of the substantially flat head.