The International Thermonuclear Experimental Reactor FEAT design for a long-pulse tokamak burning plasma experiment (R=6.2 m, a=2 m, B=5.3 T, I=15 MA) is intended to achieve extended burn in inductively driven deuterium–tritium plasmas with the ratio of fusion power to auxiliary heating power, Q, of at least 10 and a nominal fusion power output of ∼500 MW. It also aims to demonstrate steady-state plasma operation using noninductive current drive with a Q of at least 5. Particular features of the design are: a significant operating window for Q=10 inductive operation; long inductive pulses (several hundred seconds burn); a capability for studying steady-state scenarios, specifically in cases where α-particles make a significant contribution to the plasma pressure; disruption physics processes which are comparable to those expected at the reactor scale; and an α-particle density and heating power which permit the key issues of α-particle confinement and α-particle driven magnetohydrodynamic instabilities to be investigated under conditions appropriate to a reactor.