Fusion reactions controlled

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. 

Particle beam lusion accelerator II (PEFA-II) was designed io deliver ai least IQO trillion waits ol power and was ihe first machine Mth ihe potential to Ingnite a controlled laboratory fusion reaction. (U.S. Department of Energy)... 

Also in 1950 Sakliarov and Tamm proposed an idea for a controlled thermonuclear fusion reactor, the TOKAMAK (acronym for the Russian phrase for toroidal chamber with magnetic coiF ), which achieved the highest ratio of output power to input power of any fusion device of the twentieth centuiy. This reactor grew out of interest in a controlled nuclear fusion reaction, since 1950. Sakharov first considered electrostatic confinement, but soon came to the idea of magnetic confinement. Tamm joined the effort with his work on particle motion in a magnetic field, including cyclotron motion, drifts, and magnetic surfaces. Sakharov and Tamm realized that... 

One study has reported effects on neurobehavioral function in lead-exposed workers at mean PbB levels of 50 pg/dL (Williamson and Teo 1986). Neurobehavioral function was measured using tests that are based on information processing theory in 59 lead workers and 59 controls matched for age, type of job, time on the job, education level, smoking history, and alcohol consumption. Statistically significant decreases in the lead-exposed workers were seen for critical flicker fusion reaction, simple reaction time, tracking speeds, hand steadiness tests, and sensory store memory. Sensory store memory speed showed a low but statistically significant correlation with PbB concentrations. Measurements of neurobehavioral function seemed well chosen, and repeated measures with associated appropriate statistics were used. 

Carrying out fusion reactions under controlled conditions requires temperatures of millions of degrees. As you can imagine, this poses many technical difficulties, especially when it comes to the large-scale production of energy. For example, one major problem is that any reaction vessel being used would melt and vaporize long before these temperatures were reached. 

Other uses of lasers include eye surgery on detached retinas, spot welding, holography, isotope separation, accurate determination of the moon s orbit by reflection of laser light off a reflector placed on the moon s surface, and laser-guided bombs and missiles. Possible future uses include terrestrial and extraterrestrial communication, applications to computers, and production of the high temperatures needed for controlled nuclear-fusion reactions. 

On Earth, scientists are studying plasmas as a source for nuclear fusion reactions. In theory, if we can understand howto make atoms combine nuclei in controlled conditions, we can produce large amounts of energy that could be used to make electricity. 

But controlling a fusion reaction is a formidable job. Extraordinary conditions are required for igniting the reaction and for containing it. Decades of effort by scientists in a number of countries to tame the process have thus far been unsuccessful. The hydrogen bomb, far more powerful than the A-bomb, is an example of a successful thermonu-... 

For a controlled nuclear fusion reaction the following parameters are important ... 

The problems to be solved in controlling the nuclear fusion reaction have, however, been enormous. The most obvious challenge is simply to find a way to hold the nuclear fusion reaction in place as it occurs. One cannot build a machine made out of metal, plastic, glass, or any other common kind of material. At the temperatures at which fusion occurs, any one of these materials would vaporize instantly. So how does one contain the nuclear fusion reaction ... 

Nuclear power is any method of doing work that makes use of nuclear fission or nuclear fusion reactions. hi its broadest sense, the term refers to both the uncontrolled release of nuclear energy, as in fission or fusion weapons, and to the controlled release of energy, as in nuclear power plants. Most commonly, however, the expression nuclear power is reserved for the latter. Approximately 430 nuclear reactors devoted to the manufacture of electricity are operating worldwide. 

As with fission, scientists and nonscientists alike expressed hope that fusion reactions could someday be harnessed as a source of energy for everyday needs. This line of research has been much less successful, however, than research on fission power plants, hi essence, the problem has been to find a way of producing, in a controlled, sustainable fashion, the very high temperatures (millions of degrees Celsius) needed to sustain fusion. Optimistic reports of progress on a fusion power plant appear in the press from time to time, but some authorities now doubt that fusion power will ever be an economic reality. 

Scientists are investigating ways to control fusion reactions so that they may be used for both energy generation and research. One problem is that starting a fusion reaction takes a lot of energy. So far, researchers need just as much energy to start a fusion reaction as is released by the reaction. As a result, fusion is not a practical source of energy. 

Nuclear fusion provides the energy of our sun and other stars. Development of controlled fusion as a practical source of energy requires methods to initiate and contain the fusion process. Here a very powerful laser beam has initiated a fusion reaction in a 1-mm target capsule that contained deuterium and tritium. In a 0.5-picosecond burst, 10 neutrons were... 

Recent attempts at the containment of lower temperature plasmas by external magnetic fields have been successful, and they encourage our hopes. Fusion as a practical energy source, however, lies far in the future at best. The biggest advantages of its use would be that (1) the deuterium fuel can be found in virtually inexhaustible supply in the oceans and (2) fusion reactions would produce only radionuclides of very short half-life, primarily tritium (rj/2 = 12.3 years), so there would be no long-term waste disposal problem. If controlled fusion could be brought about, it could liberate us from dependence on uranium and fossil fuels. 

Fusion power generators are inherently safe. The magnetic confinement of the plasma must be carefully controlled and balanced to sustain the nuclear reaction. Any disturbance of the operating conditions will result in termination of the reaction. No combination of system failure, operator error, natural disaster or sabotage can cause the fusion reaction to run away. A nuclear explosion, melt down or similar catastrophic accident is not possible. A violent event, one of sufficient magnitude to disrupt the total reactor, could cause a chemical or electrical fire similar to any industrial fire. 

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