April 30, 1997

FPN97-11 Fusion Program Notes

U.S. ITER Design Report Review

The U.S. has completed its national review of the ITER Detailed Design Report (DDR). The review was carried out by over 80 members of the U.S. fusion community, organized into 10 specialty subpanels, reporting to an Overview Panel chaired by Robert W. Conn, Dean of the School of Engineering, University of California at San Diego. Copies of the Panel's report and its appendices are available through electronic file transfer from U. S. ITER Home Team leader Charles Baker (cbaker@iter.ucsd.edu) or from John Galambos at Oak Ridge National Laboratory (galambosjd@ornl.gov). The panel report was submitted to, and "endorse fully" by the DOE Fusion Energy Sciences Advisory Committee (FESAC) at its April 17-18 meeting. The FESAC transmitted their endorsement to DOE Director of Energy Research, Martha Krebs, by letter April 21. The FESAC told Krebs that "The ITER team has made impressive progress in developing the ITER design. This is a tribute to Dr. Robert Aymar, Director of the ITER-JCT, and to the Home Teams." While endorsing the DDR, the FESAC noted, "In our review, various areas are identified in which more work is required to confirm design decisions and to narrow the uncertainties in performance projections."

Noting that the overall performance of ITER could be characterized by its "Q-value," where Q is the ratio of the fusion power to the external source of input power to the plasma, and that a Q of 5 "is a system in which the fusion plasma self-heating power from the alpha particles equals the external source of plasma heating power," the panel said that "ITER will be considered a scientific success if in the BPP (Basic Performance Phase) it demonstrates strong self-heating (say Q greater or equal to 10) of a long-pulse D-T plasma, although this will be a significant technological achievement as well." They comment that "ITER will be considered a technological success if in the EPP (Extended Performance Phase) it demonstrates reliable operation for an extended period (say about 10 years) with a neutron fluence of about 1 Megawatt per square meter." They say that "When combined with further improvements in plasma performance and plant availability, detailed studies suggest that the design of an attractive fusion DEMO power plant will be possible." The panel congratulated the ITER designers for drawing "widely from the world tokamak experience-base" and for involving "experts world-wide." They said, "Our overall assessment is that the ITER engineering design represented in the DDR is a sound basis for the project to proceed."

With respect to the controversy over the projected performance of ITER (Science Magazine, December 6, 1996 and January 17, 1997), the panel said that "In the Panel's estimation, based on extrapolated tokamak confinement data, the expected performance of ITER's base operations mode ranges from that of fusion ignition (Q of infinity) to a moderately self-heated burning plasma (Q of about 4)." They said "There is high confidence that ITER will be able to study long pulse burning plasma physics under reduced conditions (Q greater or equal to 4), as well as provide fundamental new knowledge on plasma confinement at near fusion-reactor plasma conditions. Achieving ignition is a reasonable but challenging goal."

The panel said that they "would like to re-affirm the importance of the key elements of ITER's mission -- burning plasma physics, steady-state operation, and technology testing. The Panel has great confidence that ITER will be able to make crucial contributions in each of these areas."

For more information, contact: Stephen O. Dean