The STEAM Facility: Design and Analysis

In recent years, relevant efforts have been undertaken by EUROfusion consortium to pursue the technological development of the DEMO fusion power plant. The complex design of the machine foresees the coexistence and integration of many components commonly adopted in nuclear industry, which need to be tested and qualified during the pulsed regime imposed by the plasma power phases (pulse-dwell-pulse transitions). This unconventional operation led to the selection of the Once Through Steam Generator (OTSG) as main steam generator for the DEMO Primary Heat Transfer Systems (PHTS), since its low mass inventory enhances its responsivity to the load variations. As one of the EUROfusion main partners, ENEA is responsible for realizing a large multipurpose experimental infrastructure named W-HYDRA, to be hosted at Brasimone R.C. (Italy), conceived to investigate the water and lithium-lead technologies applied to the DEMO Water Cooled Lithium Lead Breeding Blanket (BB) and Balance of Plant (BoP) systems. Among the facilities constituting this new platform, STEAM will experimentally investigate the DEMO BoP thermalhydraulics, focusing on the steam generator of the BB PHTS, in order to qualify its performances and suitability under its unconventional operation. This paper aims at presenting a 3.1 MW OTSG mock-up to be tested in the STEAM facility, obtained by a power-to-volume scaling procedure from the BB OTSG. Thermal-hydraulic analyses have been performed with RELAP5/Mod3.3 code to support the scaling process and to investigate the overall performances, while CFD code Ansys CFX has been used for the hydraulic optimization of the component.