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#368 - The Promise of Fusion Energy, 15-Dec-1993

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

=====

[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; new
york times; washington post; controlled fusion energy; tokamak; lyman
spitzer, jr; h-bomb; nuclear weapons; tritium; deuterium; plasma;
hydrogen; helium; neutrons; lithium; aaas; lawrence lidsky; mit;
fission; nuclear power; accidents; leaks; radioactivity; radiation;
radioactive waste; proliferation;