Fusion versus Fission – Difficult versus Easy

Yesterday morning (3 March 2005) I heard a story on National Public Radio (NPR) that reminded me why I chose an engineering focused career instead of one focused on science. (Aside: I carefully avoid calling myself an engineer, though I served as one in the Navy for a couple of decades. My undergraduate degree is in English and I hold no certifications as a practicing engineer.)

The story, which can be heard on the Internet at Bubble Physics Explored in Fusion Quest. was about a scientific experiment that used ultra sound to heat up concentrated sulfuric acid in a test tube. The sound waves cause tiny – less than 1 micrometer – bubbles to be formed in the liquid. These tiny bubbles quickly collapse and emit a very short – less than 12 picoseconds – duration, short wavelength light pulse. The phenomenon is repeatable enough to have a name – sonoluminescence. It was first discovered in 1934 by scientists from the University of Cologne. (H. Frenzel and H. Schultes, Z. Phys. Chem. B27, 421 (1934)

Note: The details about the bubble size, the duration of the light pulse and the initial discovery came from Sonoluminescence: an Introduction, not from the NPR story. I cannot help it, I get curious and dig deeper when I hear an interesting story. You can find even more details of the science associated with sonoluminescence is from a paper titled Observations of Single-Pulse Sonoluminescence

The NPR story and the information that I learned about sonoluminescence were stimulating from an intellectual point of view. It is irritating, however, that NPR, Lawrence Livermore National Laboratory and the other researchers involved in studying the phenomenon tantalize readers and listeners by suggesting that more intense and well funded investigation of sonoluminescence might contribute to a solution to the world’s energy demands. I am not impressed by people that take the leap from tiny bubbles in a test tube to discussing the possibility of creating nuclear fusion, the phenomenon where atomic nuclei overcome their natural repulsion and join together to form a different element and release vast quantities of energy per unit mass.

In fact, I am extremely frustrated by the fascination that scientists, politicians and many other interested observers have with nuclear fusion when nuclear fission is so much easier and provides a much clearer path to alleviating the very real human problems associated with insufficient or dirty sources of power. Fusion research has provided career work for hundreds, if not thousands of scientists and has consumed tens of billions of dollars over a fifty-year period. Massive machines and millions of kilowatt hours of energy have been dedicated to studying ways to produce controllable fusion without so much as a kilowatt-hour of energy to show for the effort.

The contrast with fission’s historical performance is rather remarkable. In 1932, James Chadwick discovered the neutron. In 1934, Fermi aimed neutrons at uranium and produced some interesting results that he initially interpreted as forming new transuranic elements with higher and higher mass numbers. He found that more of the interesting new materials were formed if he aimed his neutrons through a layer of paraffin before the uranium. Ida Noddack suggested that he might have broken some of the larger nuclei into smaller pieces, but her interpretation was ignored for almost five years.

In 1939, Lise Meitner and Otto Frisch suggested that the new materials formed by hitting uranium nuclei with neutrons were actually elements in the middle of the periodic table that formed when the neutrons broke uranium nuclei into pieces. Otto Hahn and Fritz Strassman almost immediately confirmed their hypothesis when they identified barium and lanthanum in the material that was formed by aiming neutrons into uranium. Within a year, more than a dozen different teams around the world performed experiments confirming that neutrons will break apart – fission – uranium.

The process also released additional neutrons and showed a path toward a reaction that could be self-sustaining and release vast quantities of energy without external stimulation. Leo Szilard, who had been thinking about atomic chain reactions since 1932, proposed the possibility of a nuclear reactor that could produce enough heat to do useful work. He and Enrico Fermi were awarded a patent for such a device in 1955 – the delay was due to the intervention of a world war and the subsequent cold war period of atomic secrecy.

During the final months of1942, Enrico Fermi and his team built a working reactor using a simple stack of graphite bricks and lumps of reasonably pure uranium metal. They even called it a “pile” to describe the simple nature of its construction. Cadmium coated strips of wood with three separate means of movement served to control the device. The pile – Critical Pile Number 1 (CP1) – worked just as planned and was eventually moved to Argonne National Laboratory given some shielding and operated for a number of years.

By 1955, nuclear fission was being used in one of the most challenging power applications imaginable – reliably propelling large submarines with human crews at high speeds during sustained underwater operations. By 1957 the Shippingport nuclear power plant was producing and selling electrical power on a commercial scale and by 1973, there were enough nuclear power plants operating, under construction and on order in the United States to produce more total electrical power each year than all of the power plants in the country did in 1963.

In 2004, the electricity produced in nuclear fission power stations had the energy equivalent of more than 12 million barrels of oil per day and none of those stations produced any air pollution as the result of their operation. Zero air pollution means no greenhouse gases, no acid rain, no small particle soot, no mercury, and no smog inducing nitrogen oxides. All of the waste products from fission reactors are tightly controlled and most remain in reasonably small containers at the site where the power was produced. In contrast to the fossil fuel competition, nuclear reactors do not need tall smoke stacks in order to disperse their waste products all over the globe.

The electricity that has been produced by nuclear power plants since 1957 has been sold for hundreds of billions of dollars and paid back all initial investments many times over. It could have produced so much more if it were not for the dedicated efforts of thousands of people to slow its development down.

In contrast, fusion has never produced usable power and has consumed tens to hundreds of billions of dollars worth of resources. There might have been a few interesting discoveries made along the way, but there is no indication yet that we are any closer to the holy grail of cheap, inexhaustible energy “from the same source as powers the sun” as fusion supporters love to say.

I have to give credit to Mr. Suslick, the scientist in NPR’s story, who quoted one of my favorite sayings about nuclear fusion – “Nuclear fusion is the power supply of the future. Always has been and always will be.”

During my cynical days (and I have many of them), I attribute the relative fascination with fusion versus the fear of fission to the fact that fission is a successful energy source while fusion is a shimmering goal that seems to always be a few years away. You see, dream energy sources do not win market share and do not affect the incredible economic power that current fossil fuel suppliers have captured during the past 150 years.

During the past 40 years or so, anyone who decided to publicly oppose nuclear fission could be assured of a steady stream of donations. For a long time, I was confused by that fact, but then I began following the money trail. In many cases, the source of those funds can be traced to fossil fuel interests, who donate under the Sun Tzu dogma of “the enemy of my enemy is my friend.” People interested in selling fossil fuel do not want the competition that nuclear fission can provide, so they support politicians, intervenors, protesters, journalists, and even scientists in their anti-fission efforts.