WELDING TECHNOLOGY DEVELOPMENT FOR THE FABRICATION OF ITER BLANKET SHIELD BLOCK IN KOREA

The ITER blanket shield block will be fabricated by the conventional process based on drilling, milling and welding of forged stainless steel blocks. For the adaptation of conventional method, one of the most important tasks to be verified is to develop the electron beam welding (EBW) technologies for the block to block joint. In addition, after drilling and milling for cooling passages, plugging techniques satisfying the requirements for the welding section should be developed. Three joining technologies, the electron beam welding for thick blocks, joining of lids and plugs, and attachment of flow drivers, were investigated and the results are summarized in this paper. Electron beam welding parameters for 70 and/or 110 min thickness blocks satisfying the requirements in accordance with ASME code were established. It was also found that slower welding speed could suppress the formation of voids and porosities in weld metal. From the welding test results of mock-ups, optimal concepts on the weld design for front header lids or plugs were suggested.