Integrated design and optimization of the advanced tokamak fusion pilot plant*

A full-device FPP design is produced based on a systems code solution that is optimized to generate 200MW(e) while minimizing capital cost and operational risk. Integrated modeling by the OMFIT STEP workflow shows that the high beta poloidal scenario simultaneously achieves high pressure (β_N>3.5), high energy confinement (H₉₈~1.5), and high bootstrap fraction at moderate edge safety factor (q₉₅~5). Transport through the scrape-off layer to the divertor targets are modeled by the SOLPS-ITER and UEDGE codes, which confirm that a detached long-legged divertor is sufficient to dissipate 2.75 GW/m² poloidal heat flux. Structural, thermal, electromagnetic, and neutronics modeling of the magnet coils and breeding blanket show that balanced design choices reduce engineering risks while still meeting operational goals. The use of high temperature superconductors (HTS) reduces the coil radial builds and enables in-situ magnet fabrication. The high temperature SiC-based GA Modular Blanket (GAMBL) is developed as an aggressive concept to permit use of an efficient closed-loop Brayton cycle, while a novel low-temperature DCLL blanket design is also developed as a conservative alternate approach that eliminates the need for flow-channel inserts and allows for coupling to a high-TRL Rankine cycle. These findings indicate that the advanced tokamak is a cost-effective path toward net-electric fusion power, and that construction and operation of a U.S. facility may be feasible before the end of the 2030s.