Fusion, nuclear requirement

The production of 10 TW of nuclear power with the available nuclear fission technology will require the construction of a new 1 GWe nuclear fission plant every day for the next 50 years. If this level of deployment would be reached, the known terrestrial uranium resources will be depleted in 10 years [3], Breeder reactor technology should be developed and used. Fusion nuclear power could give an inexhaustible energy source, but currently no exploitable fusion technology is available and the related technological issues are extremely hard to solve. 

The occurrence of these and similar fusion reactions requires extremely high temperatures on the order of several million degrees— that is, temperatures of a magnitude comparable to those made possible only by the energy release characteristic of nuclear reactions, including fission. 

Where did the carbon come from The universe is primarily composed of hydrogen, with lesser amounts of helium, and comparatively little of the heavier elements (which are collectively termed metals by astronomers). The synthesis of elements from the primordial hydrogen, which was formed from the fundamental particles upon the initial stages of cooling after the Big Bang some 15 Gyr ago, is accomplished by nuclear fusion, which requires the high temperatures and pressures within the cores of stars. Our Sun is relatively small in stellar terms, with a mass of c.2 X 1030kg, and is... 

Both fusion and fission reactions can be used in bombs. The fusion reactions require a very high temperature to get started, so they are initiated by fission reactions. (When controlled at slower rates in nuclear reactors, fission reactions are used to produce power and additional nuclear fuel.)... 

Much of the world s separated plutonium has been used for nuclear weapons (Table 1). It is probable that 5 kg or less of Pu is used in most of the fission, fusion, and thermonuclear-boosted fission weapons (2). Weapons-grade plutonium requires a content of >95 wt% Pu for maximum efficiency. Much plutonium does not have this purity. 

It IS often stated that unclear fusion tvill produce no radioactive hazard, but this is not correct. The most likely fuels for a fusion reactor would be deuterium and radioactive tritium, which arc isotopes of hydrogen. Tritium is a gas, and in the event of a leak it could easily be released into the surrounding environment. The fusion of deuterium and tritium produces neutrons, which would also make the reactor building itself somewhat radioactive. However, the radioactivity produced in a fusion reactor would be much shorter-lived than that from a fission reactor. Although the thermonuclear weapons (that use nuclear fusion), first developed in the 1950s provided the impetus for tremendous worldwide research into nuclear fusion, the science and technology required to control a fusion reaction and develop a commercial fusion reactor are probably still decades away. 

Nuclei suitable for fusion must come near each other, where near means something like the nuclear radius of 10" cm. For positively charged nuclei to make such a close approach it requires large head-on velocities, and therefore multimillion-degree Celsius temperature. In contrast, fission can occur at normal temperatures, either spontaneously or triggered by a particle, particularly an uncharged neutron, coming near a fissionable nucleus. 

As an energy source, nuclear fusion possesses several additional advantages over nuclear fission. In particular, light isotopes suitable for fusion are far more abundant than the heavy isotopes required for fission. You can calculate, for example (Problem 73), that the fusion of only 2 X 10-9 % of the deuterium ( H) in seawater would meet the total annual energy requirements of the world. 

One possible way to achieve nuclear fusion is to use magnetic fields to confine the reactant nuclei and prevent them from touching the walls of the container, where they would quickly slow down below the velocity required for fusion. Using 400-ton magnets, it is possible to sustain the reaction for a fraction of a second. To achieve a net evolution of energy, this time must be extended to about one second. A practical fusion reactor would have to produce 20 times as much energy as it consumes. Optimists predict that this goal may be reached in 50 years. 

Shizgal et al. (1989) have listed a large number of processes that require an understanding of electron thermalization in the gas phase. These range from radiation physics and chemistry to radiation biology, and connect such diverse fields as electron transport, laser systems, nuclear fusion, and plasma chemistry. Certainly, this list is not exhaustive. 

Big Bang nucleosynthesis produced only H and He atoms with a little Li, from which nuclei the first generation of stars must have formed. Large clouds of H and He when above the Jeans Mass condensed under the influence of gravitational attraction until they reached the temperatures and densities required for a protostar to form, as outlined. Nuclear fusion powers the luminosity of the star and also results in the formation of heavier atomic nuclei. 

High-temperature nuclear-fusion reactors may some day be practical as renewable sources of energy for hydrogen production, but they are most likely many years away. Typically, over 100 million degrees F temperatures are required for nuclear fusion to occur and this technology, while under development, is not expected to be commercially viable in the near future. 

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