Distortion in fusion reactor coil case

Part of the structure of the proposed International Thermonuclear Experimental Reactor (ITER) consists of toroidal field coil cases.

One of TWI's industrial members had a contract with ITER to develop the procedures for fabrication of these coil cases. Each coil case consists of a 470 tonne D-shaped box with a 1.4m square hollow section fabricated from AISI 316LN stainless steel plate and forgings up to 350mm thick. The distortion tolerances for the coil case are critical.

  • TWI was called in to advise the contractors on the development of procedures for predicting the distortions and residual stresses due to welding.

  • TWI assisted in drawing up a programme of work including manufacturing of test pieces, measurement of temperatures and distortions and weld simulation modelling.

  • The development programme provided validated methods for predicting the distortion in the coil case. With this information, machining allowances can be minimised, thereby producing significant cost savings.

  • TWI also developed procedures for welding thick section 316LN stainless steel using electron beam welding.


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