Thermal-hydraulic analysis of WCLL BB First-Wall mock-up in Water Loop facility under transient conditions

The EUropean DEMOnstration Power Plant (EU-DEMO) represents a milestone in nuclear fusion research, serving as crucial step towards the realization of commercial fusion energy production by bridging the gap between current research efforts and future industrial-scale deployment. A key component of the reactor is the Breeding Blanket (BB) that must perform several essential functions for the proper DEMO operation. Two primary concepts for BB have been proposed for DEMO: the Water Cooled Lithium Lead (WCLL) and the Helium Cooled Pebble Bed (HCPB). Both concepts are going to be tested under realistic fusion reactor conditions in ITER, in the form of Test Blanket Modules (TBMs). In this framework, at the ENEA R.C. Brasimone, the construction of an experimental infrastructure called W-HYDRA is ongoing. It is dedicated to the investigation of the water and lithium-lead technologies applied to the fusion research field. As part of the W-HYDRA infrastructure, Water Loop facility will investigate WCLL BB components, such as a First-Wall (FW) test section. The design characteristics and performance of the mock-up will be assessed to provide valuable experimental results in view of DEMO operation. The present paper is focused on the thermal-hydraulic numerical study of the WCLL BB FW test section within Water Loop facility using RELAP5/Mod3.3. Specifically, the study investigates expected operating transients (i.e., pulse-dwell and dwell-pulse transients) and accidental scenarios (i.e., Loss Of Feedwater Accident, LOFA), with the aim of supporting the design phase by providing preliminary results on the Water Loop facility and on the mock-up operation.