[en] This report, prepared for Gas-Cooled Reactor Associates by United engineers and Constructors Inc. under Contract No. GCRA/UE and C/81-203 presents a conceptual design and capital cost estimate for a reference 2240 MW(t) High Temperature Gas-Cooled Reactor Steam Cycle/Cogeneration (HTGR-SC/C) plant. In addition, an initial design and cost estimate has been prepared for a modified turbine plant which enables the HTGR-SC/C to operate in a variable cogeneration cycle ranging from maximum cogeneration to full electrical generation to satisfy a range of process steam supply requirements. In addition, the three available sizes for the HTGR are evaluated economically against comparably sized coal fired plants based on capital costs and cost of steam delivered to a process user