The new layout and regulation of the ‘pulsating’ power conversion system of EU DEMO WCLL for an effective and safe control of pulse-dwell transitions and increase in plant efficiency

Abstract

EUROFUSION DEMO is a Fusion Power Plant concept under assessment, based on Tokamak technology. Regarding the Balance of Plant definition, particular effort has been posed to the design of the Power Conversion System (PCS), thermally coupled to the Primary Heat Transport System. Several architectures of the PCS have been assessed, and the present work is focused on the PCS, based on the Rankine Cycle technology and equipped with a Small Energy Storage System (ESS) operated with Molten Salt. A new Energy Map has been released in 2021, revealing uncertainties on the thermal power deposited on the different in-Vacuum Vessel components (i.e. Breeding Blanket, Divertor, Limiters and Vacuum Vessel) and rejected to the coolant of related cooling circuits. This fact leads to several (12) possible operating scenarios. The following treatment will be analyzed the 2022 PCS Small ESS concept design review, performed by the industry with the main aim to align the new layout with the updated thermal inputs and its comparison with the preliminary design developed in 2018. Design novelties will be highlighted, especially those that dealt with improving the cycle control, robustness, safety of the operation and efficiency. The outcomes of the transient analysis will be shown and compared, to verify the mechanical and thermal stress during the DEMO period (pulse/dwell). Finally, a performance and efficiency analysis of the 2022 PCS layout is also presented and compared to 2018 configuration.