SKB manage the storage and disposal of Sweden's nuclear waste (see Reduced Pressure EB case study). The manufacture of canisters from 50mm thick copper, and the sealing of lids onto these canisters require a thick section copper joining process with very high integrity. Reduced Pressure EB welding on full diameter components was proven using TWI designed and manufactured RF excited 100kW EB equipment at SKB's Canister Laboratory. As an additional and complementary technique SKB also commissioned TWI to develop Friction Stir Welding (FSW) in 50mm thick copper.
TWI has demonstrated that a TWI designed and built experimental FSW machine can produce high integrity full circumferential lid to canister welds. Critical to this success was the development of unique FSW tools and also a novel weld cycle control system. In parallel with this work at TWI, a FSW machine has been built by ESAB, Sweden and installed in the Canister Laboratory where the development of FSW continues towards the production application with on-going TWI support.