The idea is to have water or molten salt cool the walls of the torus from outside, and those drive ordinary turbines like any other generator. The main issue is that particles fly out of the confined plasma donut and degrade the walls, whose dust flys into the plasma and reduces the fusion efficiency. They’re focusing on the hard part - dealing with the health of plasma sustainment and the durability of the confinement walls over time. Hot thing that stays hot can boil water or salt to drive regular turbines, that’s not the main engineering challenge.