December 17, 1996
FPA Letter to Science
The following letter has been faxed today to the editors of Science magazine, in response to their article on ITER in the 6 December issue (See FPN-25 & 26).
To the Editor, Science:
Your December 5 press release, "Multibillion-dollar Fusion Reactor Won't Work, Say Scientists in 6 December 1996 Science News Report," set off a wave of unwarranted negative press stories telling the world that "ITER won't work." ITER (the International Thermonuclear Experimental Reactor) is under continuous design review by international teams of experts. The model described by author Glanz is only one of many that ITER designers consider. According to the minutes of the 13-16 October 1996 meeting of the ITER Expert Group on Confinement Databases and Modeling, "The Dorland-Kotschenreuther model performed no better than any of the other models being tested." These other models predict adequate ITER performance. The ITER Technical Advisory Committee (TAC) issued a statement on 7 December, stating "The TAC's overall assessment of the physics basis of ITER its that the present design parameters have been well-chosen for meeting ITER's technical objectives."
Glanz's statement that the new model "derives the rates (of heat loss) directly from basic physics principles" and that this is a major departure from the circumstance that "physicists designing new tokamaks have been forced to extrapolate from experiments to estimate how fast this complicated turbulence will cause heat to leak across fields" is both incorrect and naive. The Dorland-Kotschenreuther model treats only the inner portion of the plasma from first principles and makes a number of additional assumptions in order to compare to existing experiments and to make predictions. Designers of complex systems such as aircraft, nuclear power plants, and now fusion experimental reactors, use empirical formulas based mostly on fits to experimental data. This is not likely to change anytime soon, in spite of the fond wishes of author Glanz.
For more information, contact: Stephen O. Dean