Design Approach for FESS-FNSF In-Vessel Components and Constraints Imposed On Radial/Vertical Build Definition

The Fusion Nuclear Science Facility (FNSF) is an essential element of the U.S. developmental roadmap to fusion energy. The facility displays the complex integration of tokamak components and subsystems in fusion environment while testing and developing fusion technologies for the U.S. demonstration (DEMO) plant. The integration of the neutronics, shielding, and activation assessments is a key element to the success of FNSF operation. This paper overviews the engineering aspects of the tokamak-based FNSF study and presents an integral scheme that considered the overall configuration, radiation limits, top-level design requirements (including maximizing the tritium breeding ratio), smart selection of low-activation materials for each component, radial build optimization and definition, environmental and safety constraints, and upper temperatures for the reuse of reduced activation ferritic martensitic and bainitic structures after severe loss of coolant accidents.