The Promise of Nuclear Fusion

The Process of Nuclear Fission 786 The Promise of Nuclear Fusion 789 CHAPTER REVIEW GUIDE 790 PROBLEMS 792... 

Since the earliest days of the atomic age, physicists and engineers have predicted the coming of practicable nuclear fusion within ten years or a generation. Histoi y therefore offers many reasons to be skeptical about the promise of nuclear energy. At the same time, this unparalleled form of energy is not going to return to the Pandora s box pried open by the Manhattan Project more than a half century ago. 

Fusion promises to provide a nearly inexhaustible supply of hydrogen fuel as well as less radioactive waste, but temperatures of fusion reactions are too high for present materials, and the huge amounts of energy needed to start fusion reactions would explode or melt any known construction materials. The fires of nuclear fusion in our Sun provided energy for early humans long before they discovered the art of combustion, see also Chemical Reactions Chemistry and Energy Explosions Fossil Fuels. 

There are several approaches to the problem of nuclear fusion. The most promising is definitely magnetic confinement fusion. In the course of the last 50 years research on magnetically confined plasmas has brought magnetic confinement fusion to the threshold of net power production and has revealed much of the physics underlying the complex behaviour of hot plasmas immersed in a magnetic field. 

In contrast to the fission process, nuclear fusion looks like a very promising energy source, at least on paper. Although thermal pollution would be a problem, fusion has the following advantages (1) The fuels are cheap and almost inexhaustible and (2) the process produces little radioactive waste. If a fusion machine were turned off, it would shut down completely and instantly, without any danger of a meltdown. 

What should be done if both fossil-fuel and nuclear fission reactors are interdicted As Table IV shows, we are now left without usable, low-cost, large-scale energy supply sources and only the promise of better things to come if we can succeed in the cost-effective commercialization of large-scale solar or fusion technologies. During the foreseeable future, this will be unacceptable to people everywhere and will not be followed by their elected officials because the economic consequences would be calamitous and stable political structures could not survive. 

Among the various possible nuclear fusion processes, the most promising one for energy production is that between the hydrogen isotopes of deuterium (D) and tritium (1). 

In March 1989, Martin Fleischmann and Stanley Pons reported their discovery of cold nuclear fusion. They announced that during electrolysis of a solution of hthium hydroxide in heavy water (DjO) with a cathode made of massive palladium, nuclear transformations of deuterium at room temperature can be recorded. This announcement, which promised humankind a new and readily available energy source, was seized upon immediately by the mass media in many countries. Over the following years, research was undertaken worldwide on an unprecedented scale in an effort to verify this finding. 

Hydrogen has widespread use in ammonia synthesis and welding, as rocket fuel, reducing agent (e.g. for fats, desulfurization of oil products, etc.). H2 is the promising fuel of the future hydrogen engines, fuel cells, and maybe even nuclear fusion. 

In nuclear fission, neutron bombardment causes a nucleus to split, releasing neutrons that split other nuclei to produce a chain reaction. A nuclear power plant controls the rate of the chain reaction to produce heat that creates steam, which is used to generate eiectricity. Potential hazards, such as radiation leaks, thermal pollution, and disposal of nuclear waste, remain current concerns. Nuclear fusion holds great promise as a source of clean abundant energy, but it requires extremely high temperatures and is not yet practical. 

How much the world lost that September is immeasurable. The complementarity of the bomb, its mingled promise and threat, would not be canceled by the decisions of heads of state their frail authority extends not nearly so far. Nuclear fission and thermonuclear fusion are not acts of Parliament they are levers embedded deeply in the physical world, discovered because it was possible to discover them, beyond the power of men to patent or to hoard. 

The CVI SiC/SiC composites are also promising for nuclear applications because of the radiation resistance of the p phase of SiC, their excellent high-temperature fracture, creep, corrosion and thermal shock resistances. Studies on the P phase properties suggest that CVI SiC/SiC composites have the potential for excellent radiation stability [5]. Furthermore, because of excellent thermal fatigue resistance, start-up and shut-down cycles and coolant loss scenarii should not induce significant stmctural damage [5]. The CVI SiC/SiC are also considered for applications as stmctural materials in fusion power reactors, because of their low neutron-induced activation characteristics coupled with excellent mechanical properties at high temperature [6-8]. 

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