TWI

With regard to the use of copper canisters for the storage of spent nuclear fuel, an investigation is presented into a cascade controller to maintain probe temperature and to control power input and tool depth during friction stir welding procedures to seal the canisters. The development of the cascade controller, based on the adjustment of one input parameter (tool rotation rate), is described in relation to probe temperature measurement by thermocouples, the use of argon shielding gas, and the objectives of the tool depth controller with respect to flash formation and the effect of thermal expansion on tool position measurements. Issues discussed include the influence of axial force on defect formation, modelling of tool depth dynamics, and the correlation between probe temperature and wormhole formation.

9th International Symposium, 15-17 May 2012, Session 5A: Process I, Paper 01