Main features implemented in the JET facility for D-T operation

One of the main objectives of the JET experiment is to reach near-ignition conditions so that significant heating of the plasma by alpha particles is achieved. This objective is reflected in the long-term JET development plan, which aims at and culminates into a 1- to 2-yr-long active operation period with deuterium-tritium (D-T) mixtures, starting around 1990. During this period, many thousand D-T shots, each producing up to 1020 neutrons, are expected, and personnel access to the machine will be impossible. This approach, where it is believed that many thousand shots are necessary for a meaningful study of alpha particle heating, has had considerable cost implications. It will be shown in this paper that many components have cost more than if D-T operation had not been envisaged, or limited to a small number of shots