Boron alloys with titanium and zirconium have been examined as core materials for fixed poison components in the S3G reactor core without success. Subsequent work has demonstrated that round rods of 18% chromium, 15% nickel, 0.2% boron-10 stainless steel contained in an unbonded low cobalt stainless cladding will serve successfully in this application. Data on the irradiation and corrosion performance, mechanical properties, and thermal cycling resistance of the poison rods are presented. The elements are prepared by forging, rolling, and drawing the core alloy to final size, then cold drawing a tube of the cladding alloy onto its surface. Details of this fabrication procedure and methods for evaluating the end product are presented.