ARIES-ACT1 is the latest in a series of tokamak power plant designs that capitalize on the high-temperature capabilities and attractive safety and environmental characteristics of SiC composites coupled with a self-cooled lead-lithium breeder. This combination offers both design simplicity and high performance, capable of operating at very high coolant outlet temperature in a moderately high-power-density device. Blankets are supported within a poloidally continuous He-cooled steel structural ring, which adds robustness and minimizes loads on the SiC modules. In order to withstand high local surface heat flux in the divertor (of the order of 14 MW/m2 time averaged), a helium-cooled tungsten-alloy divertor was adopted. About 25% of the total “high-grade” heat is thus removed by helium, to be combined with the blanket heat in order to feed the power cycle. In addition to the in-vessel power-producing elements of the design, this paper also summarizes the key features and analysis of the vacuum vessel and power conversion system.