Nuclear fusion

“ Detailed Summary of Reviewer Response to Charge Elements Since the 1987 report by Pons and Fleishmann, scientists have continued to investigate the conditions responsible for the anomalous heat production in an attempt to establish reproducible conditions for the generation of excess energy, quantify the amount of energy being released, and confirm the hypothesis that the energy is a consequence of nuclear fusion by detecting the expected nuclear reaction products. ”

“ Fortunately the use of nuclear fusion, best known from the hydrogen bomb, makes it possible to regulate the kind of radioactivity one obtains. We may make only such kinds of activity which decay before they have a chance to get into the human body.
Experience has proved that to talk about weather is not dangerous. To do something about the weather will be more risky. Shall the weather become a ward of the government? ”

“ There is a huge amount of waste heat from the propulsion system and the nuclear reactor (both fission and fusion reactions) ; The fuel will be stored in large tanks at near-absolute temperatures, and must be shielded from the waste heat of the nuclear reactions. The spacecraft will require highly efficient radiators to dissipate the thermal energy released by the interstellar drive, namely the inductors, particle beams, and fusion reaction. ”

“ The excess power observed in some experiments is reported to be beyond that attributable to ordinary chemical or solid state sources; this excess power is attributed by proponents to nuclear fusion reactions. ”

“ The radioactivity liberated spreads over the world and may do slow but cumulative damage.
Controlled Fusion
However effective a fusion bomb may be in liberating vast quantities of energy, it is not what one has in mind when 151 speaking of a fusion power station. The energy of a fusion bomb is released all at once and its only function is that of utter destruction. What is wanted is the production of fusion energy at a low and steady rate—a rate that is under the control of human operators. ”

“ Deuterons and Nuclear Fusion
The "deuteron" is a particle that consists of just one proton and one neutron locked together by the strong nuclear force. It is typically found associated with an electron, and together they qualify as a member of the set of hydrogen atoms. On Earth about one hydrogen atom out of every 6500 is deuterium-hydrogen, with a deuteron as its nucleus. (Deuterium is sometimes called "heavy hydrogen," since a deuteron has twice the mass of the more-common hydrogen nucleus, and thus water made from pure deuterium is known as "heavy water.") ”

“ When hydrogen undergoes fusion and becomes helium, only 0.7% of the original mass of the hydrogen is converted to energy. Is it possible to take a quantity of mass and convert all of it, every bit, to energy? Surely that would be the ultimate energy source. Mass for mass, that would deliver 140 times as much energy as hydrogen fusion would; it would be as far beyond hydrogen fusion as hydrogen fusion is beyond uranium fission. ”

“ Even if it can’t be prepared in quantity to begin with, it might be formed by neutron bombardment of lithium, with the neutrons being formed by the fusion reaction. In this way, you would start with lithium and hydrogen-2 plus a little hydrogen-3. The hydrogen-3 is formed as fast as it is used up. Although in the end hydrogen is converted to helium in a controlled fusion reaction as in the sun, the individual steps in the reaction under human control are quite different from those in the sun. ”

“ There is enough deuterium in the oceans of the world to supply man’s energy needs for many millions of years. One difficulty, of course, is to find a container for the reaction.
Even under stellar conditions the rate of fusion reactions is not very great. It takes approximately a billion years for only one per cent of the nuclei to react. Consequently even higher temperatures than those found in stars are required to produce large amounts of energy in a short time. ”

“ And where were the irradiated-into-radioactivity pieces of laboratory equipment, due to neutrons that are also commonly released in fusions between deuterons? How could deuterium atoms lose their electrons and approach each other closely enough to fuse? And worst of all, why was the experiment so difficult to duplicate? (But even the expert chemists who announced the discovery could not produce excess heat every time; why should physicists that are generally less-expert at chemistry expect it to be easy?) ”

“ The hypothesis that excess energy production in electrolytic cells is due to low energy nuclear reactions was tested in some experiments by looking for D + D fusion reaction products, in particular 4He, normally produced in about 1 in 107 in hot D + D fusion reactions. ”

“ No reviewer recommended a focused federally funded program for low energy nuclear reactions.
Reviewers identified two areas where additional research could address specific issues. One is the investigation of the properties of deuterated metals including possible effects of alloying and dislocations. These studies should take advantage of the modern tools for material characterization. A second area of investigation is the use of state-of-the-art apparatus and techniques to search for fusion events in thin deuterated foils. ”

“ To properly grasp the full possibilities here, simply recall that a pion can interact with a nucleon in a trillionth of a trillionth of a second. That means if the whole fusion reaction takes place in a trillionth of a second, there is still time for a trillion virtual pions to zip across the distance between them! How many of those pions can kick a different electron, and give it some energy? Every time that happens, less energy is left for the fusion to cause an He-4 nucleus to break apart. ”

“ Today's primary sources of energy are mainly non-renewable: natural gas, oil, coal, peat, and conventional nuclear power. There are also renewable sources, including wood, plants, dung, falling water, geothermal sources, solar, tidal, wind, and wave energy, as well as human and animal muscle-power. Nuclear reactors that produce their own fuel ('breeders') and eventually fusion reactors are also in this category. In theory, all the various energy sources can contribute to the future energy mix worldwide. ”

“ An enormous mass, composed mainly of hydrogen, compresses itself, through its equally enormous gravitational field, into huge densities and temperatures at its center, thus igniting the fusion reaction—while the same gravitational field keeps the sun together against its tendency to expand.
There is, as far as scientists know, no conceivable way of concentrating a high gravitational field in the absence of the required mass, and the creation of controlled fusion on earth must therefore be done without the aid of gravity. ”

“ The experimental evidence presented by the review document and oral presentations for the occurrences of nuclear reactions consisted of two general types: excess power production from an electrolytic cell containing metal electrodes (palladium is the typical metal) with a deuterated electrolyte; and measurement of expected fusion products such as 4He in electrolytic cells, or any of the other expected products observed in hot fusion, proton + triton (the nucleus of tritium, consisting of two neutrons and one proton) or neutron + 3He, in a variety of experiments. ”

“ Although the gas is at a very high temperature, it is so thin that it has very little total heat. It does not have enough heat to melt the solid walls of a container. What happens instead is that the hot plasma cools down the moment it touches the solid walls and the entire attempt to heat it is ruined.
What’s more, if you try to invest the enormous energies required to keep the plasma hot despite the cooling effect of the container walls, then the walls will gradually heat and melt. Nor must one wait for the walls to melt and the plasma to escape before finding the attempt at fusion ruined. ”

“ You mean there is an intelligent organic life-form on this planet?" the Sirian asked somewhat incredulously. He had passed this system a hundred times without suspecting such a thing.
"Well, not exactly intelligent in a galactic sense, but likely you'll agree that the principles of fission and fusion are somewhat remarkable to find mastered by a planet-bound life-form as primitive as these entities. They are ordinary, liquid-and-solid, carbon-ring, ferro-protein, bi-symmetrical bipeds—you know, the kind you find scattered about on these oxygen-rich planets. But imagine! Nuclear manipulation!" ”

“ As the temperature goes up into the tens of thousands of degrees, the hydrogen atoms (or any atoms) are broken up into free electrons and bare nuclei. Such a mixture of charged particles is called a “plasma”. Ever since physicists have begun to try to work with very hot gases, with fusion energy in mind, they have had to study the properties of such “plasma”, and a whole new science of “plasma physics” has come into existence. ”

“ Only a few, relatively rare, naturally occurring substances -- primarily Uranium-235 -- can maintain the nuclear fission chain reaction necessary for operation of these [p1083] reactors. There are thus severe constraints on the long run potential of nuclear energy for generating electricity unless new nuclear fuel is "artificially" produced. ”

“ In politics the atomic nucleus has entered as a promise and as a menace—not as a fact on which we can build and with which we can reckon.
Some technical predictions seem safe:
Nuclear energy will not render our older power plants obsolete in the near future. But nuclear energy will make it 169 possible to maintain the pace—even the acceleration—of the industrial revolution. It will be possible to produce all the energy we need at a moderate cost. Furthermore—and this is the important point—this energy will be available at any place on the globe at a cost which is fairly uniform. ”

“ This can, for obvious reasons, lead to serious instability in the overall system—most interesting systems cannot withstand the unbounded increase of any of their parameters without serious negative consequences. The basic engineering principles underlying the creation of nuclear weapons exploit this feature of positive feedback mechanisms: the destructive output of nuclear weapons results from the energy released during the fission of certain isotopes of (in most cases) uranium or plutonium. ”

“ We must find new and better answers to the imperative of the nuclear age: how to maximize the benefit of nuclear power, which I believe in, but at the same time minimize the proliferation dangers. That is a dual challenge. ”

“ If such a reactor operates for half a year and then explodes and releases its radioactive content into the atmosphere, its radioactivity will be comparable to that of a hydrogen bomb. In one important respect such an accident would be worse than a hydrogen explosion. The nuclear explosive lifts most of its radioactive products to a high altitude and the poisonous activity gets dispersed and diluted before it descends. The activity from a reactor on the other hand will remain close to the ground and might endanger the lives of the people in an area of hundreds of square miles. ”

“ When a neutron strikes the nucleus of uranium-235 (235U) or plutonium-239 (239Pu) , it may cause the nucleus to split into two roughly equal fragments, releasing neutrons and energy. This is the well-known process of neutron-induced fission, the method in which nuclear energy is produced in both reactors and bombs. [14] The most common uranium isotope, 238U, also breaks up by fission, but does so all by itself, without the need for any external neutrons. That process is spontaneous fission and it goes on at random, very much like radioactive decay. ”

“ In western Europe and North America, which today have almost 75 per cent of current world capacity, nuclear provides about one-third of the energy that was forecast for it 10 years ago. Apart from Fance, Japan, the USSR, and several other East European countries that have decided to continue with their nuclear programmes, ordering, construction, and licensing prospects for new reactors in many other countries look poor. ”

“ If we renounce nuclear weapons, we open the door to aggression. If we fail to develop clean explosives, we expose people to disaster from radioactive fallout in any serious military conflict. To our way of thinking these are weighty arguments in favor of continued experimentation and development of nuclear weapons. ”

“ If a unit charge is accelerated through a potential difference of one volt, it acquires an energy of one electron-volt. The energies required for nuclear bombardment are of the order of several million electron-volts, which can be provided by atom-smashing machines such as the cyclotron.
Even at such high energies very few of the nuclear projectiles actually find their way to a target nucleus. Most of them are slowed down by the electrons, wasting their energy in heating up the target material. Perhaps one particle out of a million will be lucky enough to induce a nuclear reaction. ”

“ As energy needs rise, as oil and gas prices surge, and production shifts more each year to more volatile and less secure areas of the world and as the pace of global warming increases, nations and the private sector are looking more and more to nuclear power to meet those needs. ”