Verification of back-plate sealing performance against Li-infiltration and corrosion-induced damage based on the bayonet back-plate concept

In the recent international fusion materials irradiation facility (IFMIF) comprehensive design report (CDR), the bayonet back-plate concept, as proposed by Italian National Agency for New Technologies, Energy and the Environment (ENEA), is one of the two promising designs for the back-plate rig in the target facility. With the present design concept, the flowing lithium inside the back-plate assembly is sealed off with a Helicoflex spring energized seal (HNV 200 low-load delta seal). During lithium jet operation the spilling of the flowing lithium would cause accumulation of lithium in the groove pocket where the seal is loaded. Due to the corrosive nature and the high diffusivity of lithium, the corrosion attack on the seal and the physical permeation of liquid lithium through the seal are two main concerns for the proposed application. The objective of the present study is to examine if such a scenario would occur in a simulated lithium-seal contact, using test rigs operated for 1 month at 250, 300 and 350 deg. C. Following the high temperature exposures, the seal surfaces were examined both visually and with scanning electron microscopy equipped with energy dispersive spectroscopy. The preliminary results showed that the seal remained intact without large damages. No apparent lithium leakage through the seal was observed