05-07-2012, 11:34 AM
ADVANCED NUCLEAR POWER
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ABSTRACT
Nuclear power is the controlled use of nuclear reactions to release energy for work including propulsion, heat, and the generation of electricity. Human use of nuclear power to do significant useful work is currently limited to nuclear fission and radioactive decay.
Nuclear energy is produced when a fissile material, such as uranium-235 (235U), is concentrated such that nuclear fission takes place in a controlled chain reaction and creates heat — which is used to boil water, produce steam, and drive a steam turbine. The turbine can be used for mechanical work and also to generate electricity. Nuclear power is used to power most military submarines and aircraft carriers and provides 7% of the world’s energy 15.7% of the world’s electricity.
International research is ongoing into various safety improvements, the use of nuclear fusion and additional uses such as the generation of hydrogen (in support of hydrogen economy schemes), for desalinating sea water, and for use in district heating systems.
INTRODUCTION
Nuclear energy uses an abundant, widely distributed fuel, and mitigates the greenhouse effect if used to replace fossil-fuel-derived electricity. The use of nuclear power is controversial because of the problem of storing radioactive waste for indefinite periods, the potential for possibly severe radioactive contamination by accident or sabotage, and the possibility that its use in some countries could lead to the proliferation of nuclear weapons. . Proponents believe that these risks are small and can be further reduced by the technology in the new reactors. They further claim that the safety record is already good when compared to other fossil-fuel plants that it releases much less radioactive waste than coal power, and that nuclear power is a sustainable energy source.
PURPOSE OF USING HEAVY WATER
The "trick" to making a working reactor is to slow some of the neutrons to the point where their probability of causing nuclear fission in 235U increases to a level that permits a sustained chain reaction in the uranium as a whole. Water makes an excellent moderator; the hydrogen atoms in the water molecules are very close in mass to a single neutron, and thus have a potential for high energy transfer, similar conceptually to the collision of two billiard balls. However, in addition to being a good moderator, water is also fairly effective at absorbing neutrons.
CONCLUSION
The more we look to the future, the more we can expect countries to be considering the potential benefits that expanding nuclear power has to offer for the global environment and for economic growth. The decision to adopt nuclear power cannot be made on a ´one-size-fits-all´ basis, new nuclear plants are most attractive where energy demand is growing and alternative resources are scarce, and where energy security and reduced air pollution and greenhouse gases are a priority.