The Division of Controlled Thermonuclear Research/U.S. Energy Research and Development Administration Program Plan for the development of Tokamak power reactors calls for a first Tokamak experimental power reactor (TEPR) to begin operation in 1985 to 1987. For the past year, an interdisciplinary project at Argonne National Laboratory (ANL) has been engaged in scoping and project definition studies for the TEPR. A preliminary conceptual design was developed to provided a focus for the studies. The ANL-TEPR has a major radius, R = 6.25, and a plasma radius, a =2.1 m. Sixteen, pure-tension-D superconducting magnets, with minor bore, Rbore =7.7 m, and vertical bore, Z = 11.9 m, provide a toroidal field of 34 kG in the plasma, with a maximum field ripple of 2%. A stainless-steel-B4C blanket/shield, which is 1 m on the inside and 1.3 m on the outside, protects the magnets and converts the nuclear energy to sensible heat, which is removed by the primary coolant, helium or H2O. The first wall is 2-cm-thick stainless steel with a 100-μm low-Z coating on the plasma side, and operates at ≤550°C. The toroidal vacuum chamber is pumped down from 10−3 to 10−5 Torr between burn pulses by thirty-two 25 000 ℓ/s cryosorption pumps, and 50 000 ℓ/s cryosorption panels maintain the vacuum in the neutral beam injectors, which are used to heat the plasma. Burn pulses of 20 to 60 s, interrupted by a 15-s exhaust and replenishment phase, are envisioned for the TEPR. The plasma properties at equilibrium are [nτ = 0.56 × 1020 m−3, T = 10 keV, βθ = 2.2, q = 2.5, Ip = 4.8 MA, PT = 129 MW(th)]. Plasma heating is accomplished by 40 MW of 180-keV neutral deuteron beam for 3 s. Approximately 100 V-s are required to induce the plasma current and maintain it against resistive losses, which requires a plasma driving system power supply that can deliver ∼450 MJ, with a peak power demand of ∼1000 MW(e). The V-s are provided by superconducting ohmic-heating and equilibrium field coils located external to the toroidal field coils. Approximately 30-MW(e) cycle-average power (η = 0.3) can be produced. If confinement is adequate for ignition (nτ = 4.2 × 1020 s/m3 = 10 × TIM), the net electrical power, after subtracting the power required to produce the neutral beam (η = 0.5) and the nonrecovered energy provided by the plasma driving system (η = 0.95), is 15 to 20 MW(e). If confinement is as poor as predicted by trapped-ion-mode (TIM) theory, 23 MW of supplemental neutral-beam heating are required to maintain the power balance, and the net electrical power is negative, although the 30-MW(e) power level can still be attained. Approximately 16 g of tritium would be consumed for each full-power day of operation. Cryogenically stable superconducting toroidal field (TF), ohmic-heating (OH), and equilibrium field (EF) coils are proposed for the TEPR. The superconductor is NbTi, with a copper (plus cupronickel for the OH and EF coils) stabilizer and stainless steel. The average current densities are 1280 A/cm2 in the TF and OH coils and 2300 A/cm2 in the EF coils. The peak fields are 75 kG in the TF coils, 37 kG in the EF coils, and 32 kG in the OH coils. The maximum hoop-stress level in the support system for the TF coils is ∼24 000 psi. A stainless-steel first wall is expected to maintain its structural integrity for integrated neutron wall loadings in excess of 1 MW-yr/m2, which would permit over ten years of operation at 0.2 MW/m2 with a 50% duty factor. The blanket/shield was designed to allow the same operation before the radiation-induced increase in resistivity of the TF stabilizer exceeded 2.5 × 10−8 Ω-cm, with a safety factor of 10. The nuclear heating in the TF coils causes a temperature rise of <0.05 K.