Fully Integrated Liquid Metal System (FILMS) for a Fusion Reactor: Conceptual Design and Scoping Engineering Analysis

Fully integrated liquid-metal (LM) plasma-facing and breeding systems offer a promising approach for future fusion reactors capable of simultaneously accommodating high heat loads, tritium breeding, and power conversion. This study introduces and evaluates for the first time the fully integrated liquid metal system (FILMS), a new concept that combines three traditionally separate subsystems into a single liquid-lithium (Li) circuit: (1) a flowing LM first wall, (2) an LM breeding blanket, and (3) an open-surface LM divertor. The Fusion Nuclear Science Facility was used as a representative testbed for integrated thermohydraulic and magnetohydrodynamic (MHD) analyses. Scoping-level analyses were performed to evaluate Li flow rates, temperatures, Reynolds and Hartmann numbers, MHD pressure drops, and pumping-power requirements for the major FILMS circuits. Two structural-material options, reduced activation ferritic martensitic (RAFM) steel and vanadium alloy, were considered together with electrically conducting and electrically insulating wall assumptions. The results demonstrate that electrically insulating configurations, representing flow-channel inserts or electrically insulating sandwich-wall concepts, substantially reduce MHD pressure drops and pumping power. For the electrically insulating vanadium-alloy case, all major circuit pressure drops remain below approximately 2 MPa and the total hydraulic pumping power remains below approximately 1% of the reactor thermal power. In contrast, the electrically insulating RAFM case remains close to the engineering pressure-drop limit and likely requires additional optimization of the inboard blanket and main-loop circuits. The study additionally demonstrates the usefulness of the electric-circuit analogy framework for evaluating coupled flow redistribution and off-design behavior of the integrated FILMS hydraulic network.