Plasma control requirements for commercial fusion power plants: A quantitative scenario analysis with a dynamic fusion power plant model

The authors constructed a dynamic simulation model of a nuclear fusion power plant on Modelica language to obtain fundamental knowledge on the plasma control requirements for the future commercial fusion power plants. The fusion power plant model was designed with a 1500-MW thermal output tokamak reactor with He-cooled Li2TiO3 solid breeder blanket (coolant outlet conditions: 8 MPa and 515.8 °C). A superheated Rankine cycle was designed to achieve the electrical output of 485.38 MW with the operating pressure of 20.5 MPa. Two plasma output patterns, a step decrease of power and a single pulse decrease of power, were simulated to assess the response of the power plant. A sudden step decrease in fusion neutron led to an immediate decrease in the blanket temperature and the first coolant temperature. In order to avoid the sharp temperature drop, a need for a turbine bypass mechanism or a He coolant boiler bypass mechanism was indicated. On the other hand, because of the delay in the plant responses, the deviation of the electrical output from steady state could be minimized by recovering the plasma output in few tens of seconds. Based on the findings, a new diagram was presented that illustrates an important plasma control requirements for future commercial fusion power plants.