Final operations of the Tokamak Fusion Test Reactor (TFTR)

In April of 1997, The TFTR completed it's final operating period bringing to a close a highly successful phase of research in plasma science. The TFTR produced over 80,000 high power plasmas since 1982 with the objectives of studying the plasma physics of large tokamaks, gaining experience in the solution of engineering problems associated with large fusion systems, and demonstrating fusion energy production from the burning, on a pulsed basis, of deuterium and tritium in a magnetically confined toroidal plasma system. In 1993, TFTR became the first magnetic fusion device to study plasmas using nearly equal concentrations of deuterium and tritium. Since that time, over 1000 D-T experimental shots and over 23000 D-D shots have been carried out demonstrating new regimes of plasma confinement, proof of alpha heating, and reactor level, fusion power densities by producing a plasma which yielded over 10 MW of fusion power at a corresponding central fusion power density of /spl sim/2.8 MW m/sup -3/. The TFTR technical systems routinely operated at or beyond the original design criteria throughout the period, maintaining an impressive machine availability of >85%, and continued to do so through the final night of operations when a plasma with a record 7.7 MJ of stored energy was attained. Safe operation of the TFTR systems in D-T has been demonstrated, with over 950 kCi of tritium processed within the constraints of a 50 kCi site limit and a 20 kCi machine limit. The Tritium Purification System "closed the loop" on the TFTR fuel cycle during the final operating campaign, processing >50 kCi of tritium at >98% purity back to the Tritium Storage and Delivery System U-Beds for further use on TFTR experiments. This paper describes the experimental results of TFTR along with the technical systems and operating routines that provided the backbone of the TFTR experimental program. Discussed are the upgrades made to the TFTR device in preparation for the final operating campaign and the present plans for the shutdown and safing of the facility.