In September, 1995, the Office of Fusion Energy commissioned a three month study to assess the recommendations made by President's Commission on the Advancement of Science and Technology (PCAST) for a reduced scope of the International Thermonuclear Experimental Reactor (ITER) mission. The PCAST suggested that a device, operating with a moderate pulse length and corresponding reduced mission for ignition and bum control, could be built at a significantly lower cost than the present ITER design. If such a machine were technically feasible and less expensive than ITER, PCAST reasoned that the U.S. could participate as a full partner in an international collaboration to build such a device.

The study's charter was to develop a design to meet the reduced mission and to compare its cost with ITER using “ITER Physics.” In addition, the study explored the cost and performance sensitivity to variations in design approach and physics performance. Finally, to better understand the cost of such a project in U.S. terms, the design example was also estimated in a U.S. Total Project Cost format.

This paper details the cost estimate approach in arriving at the cost of the PCAST machine. Since the project schedule or funding profile are yet to be established, the cost comparisons based on percentage basis to ITER were more appropriate than absolute dollar comparisons. In addition, the costs of this device were also compared to the Burning Plasma Experiment (BPX) - a short pulse ignition device designed in the early 1990's, and the Tokamak Physics Experiment (TPX) - a long pulse, advanced tokamak canceled recently by the Department of Energy (DOE) due to Congressional budget constraints. Comparisons were limited to construction costs since agreements between potential international partners on the PCAST machine could significantly impact the treatment of engineering/physics, R&D, and other costs such as construction management, engineering support during construction, and commissioning costs.

The construction costs of the PCAST device were estimated to be approximately $2,600M. This is approximately 45% of the ITER construction costs, approximately 330% of the BPX estimate, and approximately 685% of the TPX estimate. Due to budget and time constraints, cost scaling was used versus performing a “bottoms up” estimate. This approach involves considerable uncertainty. Additionally, there was also a range of costs associated with future design development. Both considerations were clearly a factor in the PCAST machine where there was relatively little time for detailed evaluation, design development, or optimization. Given these uncertainties, we believe it is most appropriate to describe the construction estimate for the PCAST machine as approximately 50% of the cost of ITER, with a range of 40% to 60%.

Using the U.S. Total Project Cost methodology, the total cost of the PCAST machine was estimated to be approximately $5.8 billion in FY-95 dollars, including contingency allowances.