Scientists at Princeton University "plunged across a new physics frontier yesterday with a series of experiments that may eventually lead to an inexhaustible source of energy," the NEW YORK TIMES announced last week. [1] The Princeton group had produced a short, controlled burst of fusion energy inside a huge machine called a tokamak near the university campus in central New Jersey. Fusion is the same reaction that makes the sun shine and makes an H-bomb so powerful. The TIMES went on to say that nuclear fusion "produces virtually no dangerous waste and, in a... reactor like a tokamak, the fusion reaction quenches itself automatically and instantly if anything goes wrong."

The WASHINGTON POST reported the breakthrough at Princeton, saying the "long-repeated promise of abundant and clean electrical power from controlled nuclear fusion--the same process that drives the sun--took a large step toward reality here late tonight as scientists achieved a new world record in the amount of power produced in a fusion reactor." [2] The POST went on to point out that a fusion reactor "uses cheap, readily available fuel and creates no hazardous waste."

The TIMES added to the excitement with an op-ed piece by distinguished Princeton professor Lyman Spitzer, Jr. who said nuclear fusion reactors "would pose almost no risk and have little adverse environmental impact." [3] Professor Spitzer's point was this: "Since controlled fusion, potentially of enormous importance to our future economy, requires sustained financing, the public should understand the general status of this effort."

What does "sustained financing" mean? Fusion buffs predict it will take another 40 years before they can build a commercial machine to generate electricity. So "sustained financing" means 4 more decades of increasing annual outlays, even if you accept the optimistic 40-year timetable for solving fusion's technical problems. So far the U.S. has sunk $9 billion into fusion and we are presently spending about $500 million each year on fusion research, which is about 3 times what the federal government spends to support public libraries.

At a time when we are closing libraries, cutting investment in schools, and steadily reducing wages for American workers, does it make sense to spend half a billion dollars each year on fusion? It's a fair question.

The idea of fusion energy was born when the first H-bomb exploded in the 1950s. Scientists realized that, if they could control all that energy, they could use it to boil water, turn a turbine, and generate electricity. Unfortunately, scientists in the 1950s underestimated how hard it would be to control a fusion reaction.

The theoretical scientific problems were big, but the practical engineering problems were even bigger. Today's nuclear power plants work by fission, splitting atoms to release energy. A fusion reactor would work by an entirely different principle. The idea of fusion is to heat up deuterium and tritium (both of which are hydrogen atoms with extra neutrons), making them so hot that their electrons are stripped away and their nuclei fuse together, forming a helium atom and releasing neutrons and energy in the process. The heat in the middle of the fusion reaction is enormous--200 to 300 million degrees Fahrenheit--and the release of neutrons is very large. (A technical detail: the neutron flux would be about 10 trillion neutrons per square centimeter per second.) No material can survive such heat; at those temperatures, everything turns into a kind of gas called a plasma. Therefore, in a fusion reactor the hydrogen atoms are compressed together inside an invisible "bottle" created by powerful magnetic fields. Because the plasma can easily become contaminated and stop working, the magnetic bottle itself must be created inside a vacuum chamber.

In order to absorb the energy of the fusion reaction and to breed new tritium fuel, the inner chamber of a fusion machine is surrounded by a blanket of lithium about 3 feet thick. Lithium burns spontaneously if it comes into contact with either air or water. Six feet from the hot fusion reaction, where the huge magnets sit the neutron flux must be nearly zero and the temperature must be close to absolute zero (459 degrees below zero, Fahrenheit). Engineering such a machine is exeedingly complex.

In 1973, 20 years into the nation's fusion energy research program, the American Association for the Advancement of Science (AAAS) raised a series of concerns about fusion energy, [4] concerns that are still valid today. As AAAS said in 1973, "Operation of a fusion reactor would present several major hazards. The hazard of an accident to the magnetic system would be considerable, because the total energy stored in the magnetic field would be... about the energy of an average lightning bolt" [100 billion joules, equivalent to roughly 45 tons of TNT]. An even greater hazard would be a lithium fire, which might release the energy of up to 13,500 tons of TNT. "But the greatest hazard of a fusion reactor... would undoubtedly be the release of tritium, the volatile and radioactive fuel into the environment," the AAAS said. Tritium is radioactive hydrogen gas; it is a tiny atom, very difficult to contain. (It can escape from some metal containers by slipping right through the metal.) Furthermore, tritium is hydrogen, which can become incorporated into water, making the water itself weakly radioactive. Since most living things, including humans, are made mostly of water, radioactive water is hazardous to living things. Tritium has a half-life of 12.4 years, so it remains hazardous for about 125 years after it is created. The AAAS estimated in 1973 that each fusion reactor would release one to 60 Curies of tritium each day of operation through routine leaks, even assuming the best containment systems. An accident, of course, could release much more because at any given moment there would be 100 million Curies of tritium inside the machine, a large inventory indeed.

In 1983, Lawrence Lidsky, a professor of nuclear engineering at Massachusetts Institute of Technology (MIT), associate director of MIT's Plasma Fusion Center, and editor of the journal, FUSION ENERGY, added to the world's knowledge of potential problems with fusion energy in a candid critique of the technology. [5]

Lidsky compared the accident potential of today's existing nuclear fission reactors to fusion reactors. Fusion reactors could not melt down the way today's fission reactors can. And the radioactive waste from a fusion machine would be much less (perhaps 0.03 percent as much waste from a fusion reactor as from a fission reactor, Lidsky believes).

However, Lidsky pointed out, "Current analyses show that the probability of a minor mishap is relatively high in both fission and fusion plants. But the probability of small accidents is expected to be higher in fusion reactors. There are two reasons for this. First, fusion reactors will be much more complex devices than fission reactors. In addition to heat-transfer and control systems, they will utilize magnetic fields, high power heating systems, complex vacuum systems, and other mechanisms that have no counterpart in fission reactors. Furthermore, they will be subject to higher stresses than fission machines because of the greater neutron damage and higher temperature gradients [differences]. Minor failures seem certain to occur more frequently," Lidsky said.

Lidsky then pointed out that there would be too much radioactivity inside a fusion reactor to allow maintenance workers inside the machine. When things break, repairs will not be possible by normal procedures. This alone will make fusion plants unattractive to electric utilities, Lidsky points out. Lidsky says no one was hurt at Three Mile Island, yet the accident was a financial disaster for the owner of the plant and ultimately for the nuclear power industry. An accident at a fusion plant could have similar consequences, he says.

Lidsky pointed out that a fusion reactor would have to be physically larger than a fission reactor to create an equivalent amount of electricity, perhaps 10 times larger. Such huge machines would be enormously expensive to build, and utilities have already turned their backs on huge machines. From the viewpoint of generating reliable power, it makes more sense for a utility to invest in several smaller machines, rather than putting all their eggs in one large, unreliable basket, Lidsky says. "All in all, the proposed fusion reactor would be a large, complex, unreliable way of turning water into steam," Lidsky concludes.

As if to drive a final nail into the coffin of fusion, Lidsky pointed out that, "One of the best ways to produce material for atomic weapons would be to put common uranium or thorium in the blanket of a D-T [deuterium-tritium fusion] reactor, where the fusion neutrons would soon transform it to weapons-grade material. And tritium, an unavoidable product of the reactor, is used in some hydrogen bombs. In the early years, research on D-T fusion was classified precisely because it would provide a ready source of material for weapons. Such a reactor would only abet the proliferation of nuclear weapons and could hardly be considered a wise power source to export to unstable governments."

Everyone in the fusion business agrees that the main attraction of fusion is the inexhaustible hydrogen fuel, offering a potential for large power output. Everyone in the fusion business also agrees--though no one ever speaks of it--that there is another inexhaustible source of energy even larger than the potential of fusion energy: light from that great fusion reactor in the sky, our sun. If we refine techniques for converting sunlight into electricity via photovolatic cells (or other ways), we will have achieved the dream of the fusion gurus, but without the radioactive hazards or the risk of proliferating weapons of mass destruction. Fusion energy would require investment of billions of dollars in each fusion reactor, thus centralizing control of our energy sources in the hands of governments, utilities and multinational corporations. Solar electricity, on the other hand, could be developed on a small scale, thus liberating people from central control. These are some of the issues the public must be informed about before an appropriate fusion research budget can be established. Puff pieces about fusion energy in the NEW YORK TIMES and the WASHINGTON POST contribute little of value to such a debate.
--Peter Montague, Ph.D.
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[1] Malcolm W. Browne, "Into a New Frontier After Fusion Success," NEW YORK TIMES Dec. 11, 1993, pg. 10.

[2] Boyce Rensberger, "Princeton Lab sets Another Fusion Record; Success Hailed as Step Toward Practical Use of Such Energy," WASHINGTON POST, Dec. 11, 1993, pg. A3.

[3] Lyman Spitzer, Jr., "Harnessing the Sun," NEW YORK TIMES Dec. 11, 1993, pg. 23. [Note how the title equates fusion with solar energy.]

[4] Allen L. Hammond, William D. Metz, and Thomas H. Maugh II, ENERGY AND THE FUTURE (Washington, D.C.: American Association for the Advancement of Science, 1973, pgs. 79-85.

[5] Lawrence E. Lidsky, "The Trouble With Fusion," TECHNOLOGY REVIEW Vol. 86 (October, 1983), pgs. 32-44.

Descriptor terms: princeton university; plasma physics laboratory; ppl; new york times; ny times; nyt; washington post; wp; controlled fusion energy; tokamak; lyman spitzer, jr.; h-bomb; hydrogen bomb; nuclear weapons; tritium; deuterium; plasma; hydrogen; helium; neutrons; lithium; american association for the advancement of science; aaas; lawrence lidsky; massachusetts institute of technology; mit; fission; nuclear power; accidents; leaks; radioactivity; radiation; radioactive waste; proliferation;