Many people are not particularly fond of nuclear energy, but we are gravitating back to it after an hiatus of some 30 years. Nuclear fission was such an exciting discovery hundred years ago. Linus Pauling (1901-1994) was born in Portland, Oregon. He became the only sole winner of two Nobel prices, one in chemistry in 1954 and the Nobel Peace Price in 1962. He hailed controlled atomic fission and controlled release of nuclear energy as the greatest inventions since the controlled use of fire. Indeed, it is the fire of heaven (some may say of hell), the fire that makes the ancient gods, the sun and the stars shine in the sky and at the same time enabled life on Earth. Of course, today we know that nothing is forever and that also the stars burn out. We know that there are elements that have half lives of the age of the solar system, like uranium, 232/92U (the first number is the total of protons and neutrons and the second is the number of neutrons), with 4.5 x 10^9 years; or even a half life of the age of the known universe, like thorium, 232/90 Th, with 13.9 x 10^9 years. But will we be able to control this heavenly fire? At best one can say that there is a small probability that we can and a larger complementary probability that we can’t, say 20/80. Linus Pauling, after the shock he suffered from the use of atomic bombs in 1945, became an ardent fighter against nuclear war and wrote the book No More War. On the day of his Nobel Peace Price award, the ban on atomic weapons testing between USA, USSR and Great Britain was signed.
Indeed, fission energy was the discovery of the ages. One kilogram uranium or thorium, elements rather widely distributed in the earth crust, held the energy of one million kg of coal. A kilogram of water is a cube of 1000 mL (10 cm x 10 cm x 10 cm). One kg of uranium occupies only 50 mL, a cube of less than 4 cm side length, a handful. Its energy equivalent is a cube of bituminous coal of 12 m side length. But the comparison is not quite that simple. The coal can be dumped into a furnace and burned within no time, the handful of 238/92 U takes 4.5 billion years for half of it to be converted into lead. The isotope 239/92 U converts faster. Half of it converts in 23.5 minutes to neptunium and from there, half of the neptunium in 2.3 days into plutonium, 239/94 Pu, which has a half-life of 24,000 years.
When fission energy’s potential was recognized it promised to relieve us of all energy worries forever. And this was then followed in short order by the promise of fusion energy that was supposed to be even better, cheaper and more effective than fission. These promising prospects appeared at a time when all the conventional energy resources, coal, water, oil and gas, had barely been scratched. In retrospect one can sympathize with those who talked about abundant energy.
It seems only a short time ago, in the 1930s, that the TVA didn’t quite know what to do with
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all the energy that was generated by the 3000 MW hydropower capacity installed in the dams. While this capacity installation demanded great sacrifice from land owners whose farms were submersed, and from fish whose free-flowing streams were impounded, it was the most efficient, reliable, and cleanest energy ever produced. Some 95 percent of primary energy behind the dam could be converted into electrical energy. Nashville was touted as the electric heated home capital of the U.S., if not the world. Then from the 1950s on coal-fired power plants took over. They should outpace hydrocapacity in the TVA system by a factor of four
or five. From the beginning there was a nagging problem with energy extraction from coal via steam: the usable electric energy obtained required more than twice the usable energy in the form of primary energy to produce it. This meant dissipation of twice the amount of the usable energy into the environment in the form of water evaporation into the air, hot water into rivers and lakes, and dirty combustion gases into the air. Presently it is rising planetary temperatures that demonstrate the unsustainability of the approach.
Running low on options, after wasting away 30 years without serious energy research, and after finally recognizing the serious thread of global climate change, we are getting ready for a new round of playing with the heavenly fire. There is not much enthusiasm in it this time, but according to estimates of anticipated world energy needs, while holding atmospheric CO2 at about 550 ppm, some 4000 nuclear reactors with 1000 to 1600 MW each are needed.
The Global Nuclear Energy Partnership proposed by the United States wants to spread nuclear energy around the world under the condition that nuclear waste reprocessing that recuperates plutonium be limited to nations that already do it. This approach is seen as the only way to limit the rise of atmospheric CO2 and at the same time provide for anticipated energy demand. This program would ultimately also aim at advanced reactors that reduce the amount of radioactive waste and its longevity, thus reducing the size and length of end storage. It would require a considerable amount of shipping of nuclear fuel to plants around the world, spent fuel back to reprocessing plants, refreshed fuel back to nuclear plants, and finally, the waste to end storage sites. For safe keeping these would be places like Yucca Mountain. While these transportation links are vulnerable they are orders of magnitude smaller than what is presently being transported in the form of oil.
But despite the urgency of a solution to the energy problem the amount of money is not there for the DOE, the U.S. representative in this international government-industry venture, to provide a reliable leadership role. Barely is a program started it is severely underfunded by Congressional budget slashing and by the continuing differences of opinion about the merits of the project.
The Go or No-Go for nuclear energy is a messy decision. Probably nobody has a clear vision of its outcome. But a weighing of all factors must dip the balance in one way or another to move on. One may argue that it is either too risky to invest in nuclear plants and better shift to other options, viable green ones, biofuels (corn is already off the table), wind, solar, etc., and come to a clear conclusion of their capabilities, given a reasonable energy demand forecast, not a wild one, as in the 1970s, but one that is tempered by high energy costs and conservation.
Especially wind energy is presently making significant inroads. Offshore wind parks profit from sea-land winds that blow day and night, especially during the summer when many areas experience high energy demands. It is a sort of indirect harvesting of large amounts of solar energy from extended areas, not unlike hydropower. But the maintenance of large wind parks (some 350 units at 5 MW as an equivalent of one 1600 MW nuclear plant) and the collection and transport of energy from them to demand centers is no minor matter. A close look at all alternative energy sources will uncover problems that make each option less than ideal or desirable.
While green energy can take over entire sectors of energy needs, such as residential and agricultural, there will be plenty of room left for nuclear base load. Nuclear power seems to have the production reliability to replace or at least reduce the present coal and gas sector that now produces 80 percent or more of all base load energy. And then there is the enormous need of the transportation sector for either hydrogen fueled or electrical cars. It is more and more the consensus that we must go for all energy alternatives that look promising over the short range, because even conventional low or no CO2 energy sources will take years to come on line, and more sophisticated energy sources are decades
To get nuclear energy ready to play an increased energy supply role the still lingering problems of operational safety and the waste disposal must be adequately addressed and solved. Instead of Generation II nuclear reactors and perhaps in a few instances of Generation III, we should be building Generation IV by now, but they are perhaps 50 years off into the future.
The Generation IV International Forum is a thirteen-country working group on nuclear energy. The U.S. is its leader, more for its role as the world’s superpower than as an advanced nuclear energy producer. The U.S. has none of the presently advanced reactors working. Three so-called advanced boiling water reactors (ABWR) of Generation III are running in Japan. Two others, known as European Power Reactors (EPR) are going up one in Finland and one in France. With 60 years life expectancy, and less uranium requirement than present models these 1600 MW reactors are the largest in the world. But they rely on converting 238/92 U to 239/94 Pu, half of which remains in the spent fuel and has to be reconverted into new fuel. A so-called core catcher under these reactors is supposed to prevent the China Syndrome should it happen against all expectations.
World-wide there are presently 26 nuclear power plants under construction, 41 are in advanced planning and 113 are in pre-planing stages. Only a relatively small number, like the three in Japan and the European types are of advanced Generation III design, the rest are conventional nuclear converters.
It is estimated that the Generation IV designs will not become available until the middle of the 21. century. Generation IV reactors will address several major problems that make them superior to present models: (1) They will not just burn fuel but also breed new fuel. (2) They will be inherently safe by using physical processes like free convection cooling instead of mechanical pumping for emergency cooling (a process the writer helped investigate 25 years ago). (3) They will achieve a more complete burn of nuclear fuel that will reduce post-operational fuel waste storage from about 100,000 years to about 500 years (given a half-life of plutonium of 24,000 years, 96,000 years would reduce 1 kg of plutonium to 62 g). (4) The high temperature gas cooled reactors (HTGR), designs developed decades ago, will operate at 900 0C reactor temperature, use inert helium gas cooling and provide process heat to split water vapor directly into hydrogen and oxygen. The very high temperatures pose as yet unsolved material problems.
The nuclear option has a major political aspect. It requires world-wide cooperation. Many countries need nuclear power because they just don’t have other energy resources. Some countries that thought they could get by without nuclear power have revised their policy and have reconsidered the nuclear option. International organizations may have to come in and play a regulatory and supervisory role so that world-wide impacting nuclear accidents can be avoided and safety from detractors can be guarantied. The approach is hazardous but basically feasible, as has been demonstrated over the
past 50 years.
Imagine the United States consisting of fifty independent states. Some would have plentiful traditional resources (coal, oil and gas), some would have large green resources (wind and sun), some would have both, and some would have none. It is the e pluribus unum that endows the U.S. with all options so that its policy makers sometimes tend to forget how lucky we are and how difficult it is for many other countries to cope with energy problems.
Correction of a nuclear double whammy in the Soupcon part of this article: Linus Pauling’s book on General Chemistry (Dover) is in error on the half-life of 239/92 U, which is 23.5 minutes, not 2.3 minutes (p. 832). Then I added my own misinterpretation by making it 2.3 months instead of 23.5 minutes. The writer apologizes for any mental pain and anguish this may have caused the reader. In the website version this error has been corrected. (VDI, 28/3/08, mg; Physics Today, July 2008, p. 19-22). WOW.
P.S.: Last month the Soupcon showed a picture of the architectonically disguised stack of the 100-year old combined heat-power plant at Beelitz near Berlin. This month I read that President Bush and his wife, while being hosted by Chancellor Merkel at Meseberg castle, were treated to the culinary specialty of the area, Beelitzer Spargel (asparagus), the white succulent asparagus that is preferentially eaten in many parts of Germany. He called it outstanding and I believe it. WOW.