Modular fusion power plant

•A concept of the fusion power development based on a modular fusion plant is analyzed.•Specific requirements to fusion modules constituting such a plant are identified.•Economic characteristics of the plant based on high field spherical tokamaks and HT superconductivity are presented. The mainstream approach to the fusion power, following the JET/JT60-SA − ITER − DEMO route, assumes increase in the size and development of new physics and technologies at each step. In this paper, we present an alternative route, based on the modular approach, when the economically feasible fusion power plant will consist of several modules, where the physics and technology are developed for a single compact module, making the development path cheaper and quicker. The economics is based on that for a modular-based plant, where many auxiliaries are shared between modules, and a regular necessary maintenance is set in a module-to-module way, providing high availability of the power plant. An expression for the cost of the generation of electricity (CoE) and identification of cost factors important for the modular approach are presented. The minimal size of a single module is determined by the physics and technologies developed up to date. The presented cost example for a modular power plant is based on the selected set of parameters for a single module and the necessary number of the modules in an economically feasible power plant. The cost of electricity (CoE), dependence of the CoE on the neutron wall loading and the effect of a module reservation are examined in detail. While the final cost of the new approach may be not significantly cheaper than for the mainstream approach, the development path has many advantages and can be affordable and much faster, supported by the combination of private and public funding.