[en] A conceptual design has been developed for an upgradable ignition test reactor (UITR) as part of the ERDA-sponsored TNS program to identify the next major tokamak device beyond Doublet III and TFTR. This reactor, which is based on the doublet plasma concept, has a major radius of 4.2 m, a minor radius of 1.2 m, and a plasma height-to-width ratio of 2.7. The plasma is contained in a water-cooled vacuum vessel fabricated of Inconel 625. A 25 cm thick helium-cooled blanket made of 316 stainless steel is installed outboard of the plasma chamber. The field-shaping coil system, shielding system, toroidal field coils, and induction coil system are installed outside the blanket. In its ITR mode, the reactor operates in moderate length pulses (30 sec) with a duty factor of 0.1 (5 min cycles). For net power experimental power reactor (EPR) operating mode, the machine operates with 90 sec pulses and a duty factor of 0.78. While the UITR initially costs about 30% more than an ITR without upgrade capability, and additional costs are incurred when implementing the upgrade, the total program costs far less than the sum of separate ITR and EPR facilities