AbstractThe HYLIFE-II fusion power plant conceptual design has evolved and improved continually over the past four years to its present form. This paper describes the FY93 reference case H1-B (nominally 1 GW(e) net output) and the enhanced case HE-B (nominally 2 GW(e) net output), which take advantage of improvements in the tritium management system to eliminate the intermediate loop and the intermediate heat exchangers (IHXs). The improvements in the heat-transport system and the steam power plant are described and the resulting cost reductions are evaluated. The new estimated cost of electricity (in 1990 dollars) is 5.1¢ kWh−1 for reference case H1-B and 3.6¢ kWh−1 for the enhanced case HE-B.