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Fusion Power: The Burning Issue
The Department of Energy is gambling on the wrong fusion approach and may needlessly burn up billions in taxpayer dollars in the process.
Fusion power research is at a crossroads. Continuing along the current path will almost certainly lead to major disappointment for one of the few long-term energy sources potentially available. After roughly 50 years of research, the Department of Energy is seriously considering moving ahead with a burning plasma experiment that for the first time would demonstrate the large-scale production of fusion. 1 The leading proposal is the International Thermonuclear Experimental Reactor (ITER). ITER has been in design for more than a decade by a team composed of technologists from the United States, Europe, Japan, and Russia. To build and bring ITER into operation would cost an estimated $5 billion to $10 billion and take roughly 10 years.
Although the goal of demonstrating the large-scale production of fusion power is laudable, there are compelling reasons to believe that the leading concept-the tokamak approach-will not be viable as a commercial electric power system. 2,3 That being the case, the burning issue is whether the investment of time, money, and people, and the diversion from more promising paths, is justified.
The following highlights some of the fundamental physics, engineering, and market realities that together show why the tokamak concept is a commercial dead-end.
Fusion requires an extremely hot plasma (an ionized gas) of fusion fuels that must be contained long enough so that usable power can be generated beyond that required to heat and maintain the plasma. The main approach to this challenging task involves the use of magnetic fields shaped to form a "magnetic bottle," which can hold a fusion plasma.
Among the various "bottles" studied, the toroidal (donut-shaped) tokamak concept has emerged as the most popular among fusion physicists. Because fundamental physics dictates that such "bottles" will slowly leak plasma under the best of conditions, high net energy-producing plasmas must be very large in size-the outer dimensions of just the ITER magnetic "bottle" structure is well over 30 meters in diameter and over 30 meters in height.
While a number of different fusion fuel cycles are possible, the deuterium and tritium (DT) cycle, which seems to be the least demanding, is currently favored. The DT fusion reaction releases most of its energy in the form of a very energetic neutron, which requires a meter or more of "blanket" material surrounding the plasma to capture neutron energy for electric power production and to slow neutrons down so that they can be absorbed.
It is well known that the absorption of neutrons induces radioactivity in almost all materials and that radioactivity can last for hundreds or thousands of years. In addition, neutrons degrade the integrity of structural materials, necessitating their replacement. The greater the neutron flux and energy, the shorter the useful life of exposed materials.
From an engineering point of view, tokamak fusion involves a myriad of difficult challenges-too many to discuss in this context-but one important engineering rule-of-thumb is particularly important: In general, the more materials in a