The development of electron beam welding technology for the fabrication and sealing of copper canisters for nuclear waste burial

The principle of using copper as the main corrosion barrier for long term storage of high level nuclear waste is now well established in Sweden. The Swedish Nuclear Fuel and Waste Management Company (SKB) first approached TWI in 1981 with a request to recommend the best means of sealing such canisters. Originally it was thought that a copper canister wall thickness of approximately 200 mm would be required for corrosion resistance and strength. Of the processes considered (i.e. electron beam welding, diffusion bonding and friction welding) electron beam welding potentially offered the greatest probability of success. Certainly at this time the proposed wall thickness was well beyond the state-of-the-art capabilities of diffusion bonding and friction welding. However, even in 1983 it proved possible to demonstrate successfully the electron beam welding of a mock-up lid assembly involving an effective wall thickness of 100 mm with an outside diameter of 600 mm. As well as the work on the development of electron beam welding sealing procedures for canisters, TWI has also been extensively involved in studies of the means of forming and fabricating canisters by electron beam welding. This paper presents a summary of the work conducted on electron beam welding of copper canister materials, together with the associated non-destructive testing requirements and techniques. 2 refs, 13 figs