Construction of hot helium leak test facility for ITER blanket shield block

The ITER Blanket Shield Block (SB) is one of the main in-vessel components that provides nuclear shielding and removes nuclear heating for the Vacuum Vessel (VV) and external vessel components. The SB, which contains internal cooling channels, is manufactured from 316L(N)-IG stainless steel, and the internal channels are designed to provide the required thermal-hydraulic performance while aiming for a water/steel ratio that results in good nuclear shielding with headers and welded cover plates. Therefore, the soundness of all SB products' welded joints must be confirmed to eliminate the risk of leakage during manufacturing and the Factory Acceptance Test (FAT). However, a test facility capable of testing large components at high temperatures has never been constructed anywhere. The ITER Korea Domestic Agency (KODA) has therefore successfully completed the construction and commissioning of two Hot Helium Leak Test (HHLT) facilities, and all SB series products are being entirely tested under RT and an elevated temperature of 250 degrees C with a maximum operational pressure of 5.0 MPa. This paper provides information on the design features of the two HHLT facilities and lessons learned from the commissioning test.