Implementation of an Outer Can Welding System for Savannah River Site Plutonium Processing Facility Available to Purchase

This paper details three phases of testing to confirm use of a Gas Tungsten Arc (GTA) system for closure welding the 3013 outer container used for stabilization/storage of plutonium metals and oxides. The outer container/lid closure joint was originally designed for laser welding, but for this application, the gas tungsten arc (GTA) welding process has been adapted. The testing progressed in three phases: (1) system checkout to evaluate system components for operational readiness, (2) troubleshooting to evaluate high weld failure rates and develop corrective techniques, and (3) pre-installation acceptance testing. A total of 190 can/lid welds were made and evaluated. During Phase I, weld failures were common due to pressure buildup and venting through the weld pool. During Phase II, characterization of the electrode contact to the weld pool and weld pool blowouts helped in the development of a corrective technique. During Phase III, a reduction in internal pressure, by controlling the final helium backfill of the can before welding, provided satisfactory weld results. The work described was performed during 2002 pre-installation testing at the Savannah River Technology Center in Aiken, S.C. before installation of an Outer Can Welder (OCW) system at the Savannah River Site (SRS) plutonium processing facility. The first OCW system was originally developed at the SRS to support similar plutonium stabilization/storage efforts at the Hanford Site (operated by Fluor Hanford Corporation).