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At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Panel Deflates Grand Fusion Experiment
22 April 1997 8:00 pm
WASHINGTON, D.C.--Scientists have thrown more cold water on a multibillion-dollar fusion project before it even attempts to ignite. A panel of U.S. physicists and engineers has raised the odds of achieving a self-sustaining burn with the current design of the planned $10 billion International Thermonuclear Experimental Reactor (ITER). And fusion scientists are worried that a more sober assessment of ITER's chances could erode congressional support just as the United States prepares for negotiations later this year with its European, Japanese, and Russian partners on whether to spend the next decade building the massive machine.
As recently as 1995, U.S. Department of Energy (DOE) officials gave ITER a 2-in-3 chance of reaching ignition, a sustained burn, without injecting power from the outside. With an outside kick of about 100 megawatts, they said, the odds of reaching ignition rose to 99.5%. However, recent advances in modeling have raised questions about the efficacy of the ITER design (Science, 6 December 1996, p. 1600).
The new report, by a team that included about 50 scientists and engineers not directly associated with the program, lengthens those odds. Although it concludes that there are no insurmountable obstacles to building and operating the machine, it paints a sobering picture of the difficult technical issues in its path. The problems range from removing tritium from waste water to the design of thermal blankets necessary to counter intense radiation. Long-pulse ignition "cannot be assured," it says, "but [it] remains a reasonable possibility." In the meantime, it states, important physics on plasma confinement could be accomplished even without ignition. And future upgrades could lead eventually to a self-sustaining burn.
The new language accurately reflects the steep road ITER must travel to achieve ignition, says DOE fusion chief Anne Davies. "The fusion community probably should have been more careful in its promises," she says about earlier pronouncements. And close scrutiny of those promises is far from over. The National Research Council, at DOE's request, is preparing a report on ITER's overall value to the United States that is due 1 December. In the meantime, ITER supporters are hoping that diminished expectations won't translate into diminished political support.