Design scoping and systems modelling of ST-E1 using the PyTok power plant simulation code

Abstract To support the pre-concept design of Tokamak Energy’s (TEs) ST-E1 fusion power plant, we developed a new systems code, PyTok. PyTok codifies plasma physics and engineering constraints within a pure Python, object-oriented framework designed for rapid design iteration and exploration of the power-plant parameter space. The code base and its human- and machine-readable data structures enable coupling to external physics codes and data-analysis tools. Informed by TEs design philosophy and techno-economic analyses, the code was used to identify an initial reference design point for ST-E1. A commercially competitive fusion power plant is achievable with a tokamak power core of major radius 5.0 m, aspect ratio 1.9 ⩽ A ⩽ 2.3 and toroidal field 3.25 ⩽ B T ⩽ 5.25 T. The selected design point serves both as a pilot plant and as a commercially competitive reactor using the same permanent power core hardware, enabled by an in-vessel component upgrade phase. The commercial phase targets steady-state operation and a normalised capital expenditure of $12 000–15 000 per kW e , corresponding to a fusion power of 2.0–2.5 GW and a net electric power of 800–1000 MW.