NUCLEAR POWER PLANT Conventional thermal power stations use oil or coal as the source as the source of energy. The reserves of these fuels are becoming depleted in many countries and thus there is a tendency to seek alternative sources of energy. In a nuclear power station instead of a furnace there is a nuclear reactor, in which heat is generated by splitting atoms of radioactive material under suitable conditions. The conversion to electrical energy takes place indirectly, as in conventional thermal power plants. The heat is produced by fission in a nuclear reactor. Directly or indirectly, water vapor (steam) is produced. The pressurized steam is then usually fed to a multi-stage steam turbine. For economical use in a power system a nuclear power station generally has to be large and where large units are justifiable. As of 23 April 2014, the International Atomic Energy Agency reports that there are 435 nuclear power reactors in operation operating in 31 countries.
History of Nuclear Energy and Power Generation The neutron was discovered in 1932. The concept of a nuclear chain reaction brought about by nuclear reactions mediated by neutrons was first realized shortly thereafter, by Hungarian scientist Leó Szilárd, in 1933. Inspiration for a new type of reactor using uranium came from the discovery by Lise Meitner, Fritz Strassmann and Otto Hahn in 1938 that bombardment of uranium with neutrons (provided by an alpha-on-beryllium fusion reaction, a "neutron howitzer") produced a barium residue, which they reasoned was created by the fissioning of the uranium nuclei. On June 27, 1954, the USSR's Obninsk Nuclear Power Plant became the world's first nuclear power plant to generate electricity for a power grid, and produced around 5 megawatts of electric power.The first commercial nuclear power station, Calder Hall in Sellafield, England was opened in 1956 with an initial capacity of 50 MW (later 200 MW). India's first research nuclear reactor and its first nuclear power plant were built with assistance from Canada. The 40 MW research reactor agreement was signed in 1956, and CIRUS achieved first criticality in 1960. This reactor was supplied to India on the assurance that it would not be used for military purposes, but without effective safeguards against such use. The technical and design information were given free of charge by Atomic Energy of Canada Limited to India. The
United States and Canada terminated their assistance after the detonation of India's first nuclear explosion in 1974. Tarapur Atomic Power Station located in Tarapur, Maharashtra is the first nuclear power reactor of India. It was estabilished in October 28, 1969. It has a total capacity of 1,400MW. Fig 2. The image is a view of the Tarapur Nuclear power plant.
Nuclear Reactions In nuclear physics and nuclear chemistry, a nuclear reaction is semantically considered to be the process in which two nuclei, or else a nucleus of an atom and a subatomic particle (such as a proton, neutron, or high energy electron) from outside the atom, collide to produce one or more nuclides that are different from the nuclide(s) that began the process. Thus, a nuclear reaction must cause a transformation of at least one nuclide to another. If a nucleus interacts with another nucleus or particle and they then separate without changing the nature of any nuclide, the process is simply referred to as a type of nuclear scattering, rather than a nuclear reaction. There are two types of nuclear reactions Nuclear Fusion Nuclear Fission
Nuclear Fusion In nuclear physics, nuclear fusion is a nuclear reaction in which two or more atomic nuclei collide at a very high speed and join to form a new type of atomic nucleus. During this process, matter is not conserved because some of the matter of the fusing nuclei is converted to photons (energy). Fusion is the process that powers active or "main sequence" stars. Fusion power is the energy generated by nuclear fusion processes. The origin of the energy released in fusion of light elements is due to interplay of two opposing forces, the nuclear force which combines together protons and neutrons, and the Coulomb force which causes protons to repel each other. The protons are positively charged and repel each other but they nonetheless stick together, demonstrating the existence of another force referred to as nuclear attraction. This force, called the nuclear force, overcomes electric repulsion in a very close range.
Most nuclear fusion reactions involve the fusion of two hydrogen isotopes (Deuterium and Tritium) to form a helium atom releasing huge amounts of energy and a neutron. Fig 3. A schematic representation of the equation of a nuclear fusion reaction. Nuclear fusion is currently in its experimental phases and is not being utilized for commercial purposes due to its requirements of high initial energy and pressure so as to overcome the coulombic forces and bring the nuclei in close proximity.
Nuclear Fission In nuclear physics and nuclear chemistry, nuclear fission is either a nuclear reaction or radioactive decay process in which the nucleus of an atom splits into smaller parts (lighter nuclei). The fission process often produces free neutrons and photons (in the form of gamma rays), and releases a very large amount of energy even by the energetic standards of radioactive decay. Fig 4. A schematic representation of the equation of a nuclear fission reaction. Fission as encountered in the modern world is usually deliberately
produced
a
man-made nuclear
reaction induced by a neutron. In an induced fission reaction, a neutron is absorbed by uranium-235 nucleus turning it briefly into an excited uranium-236 nucleus, with the excitation energy provided by the kinetic energy of the neutron plus the forces that bind the neutron. The uranium–236 in turn splits into fast moving lighter elements (fission products) and releases three free neutrons at the same time, one or more “prompt gamma rays” are produced as well.
The Various Components of a Nuclear Power Plant are: Nuclear Reactor
Cooling System Steam Generator/Boiler
Safety Valves
Nuclear Power in India Nuclear power is the fourth largest source of electricity in India after thermal, hydroelectric and renewable sources of electricity. As of 2013, India has 21 nuclear reactors in operation in 7 nuclear power plants, having an installed capacity of 5780MW and producing a total of 30,292.91 GWh of electricity while seven other reactors are under construction and are expected to generate an additional 6,100 MW. Power
Total capacity
Operator
State
Type
Units
Kaiga
NPCIL
Karnataka
PHWR
220 x 4
880
Kakrapar
NPCIL
Gujarat
PHWR
220 x 2
440
Madras
NPCIL
Tamil Nadu
PHWR
220 x 2
440
Narora
NPCIL
Uttar Pradesh
PHWR
220 x 2
440
station
(MW)
100 x 1 Rajasthan
NPCIL
Kota Rajasthan
PHWR
200 x 1
1180
220 x 4
Tarapur
NPCIL
Maharashtra
Kudankulam
NPCIL
Tamil Nadu
BWR
160 x 2
PHWR
540 x 2
VVER1000
1000 x 1
1440
1000
Advantages of Nuclear Power Plant Space requirement of a nuclear power plant is less as compared to other conventional power plants of equal size. A nuclear power plant consumes very small quantity of fuel. Thus fuel transportation cost is less and large fuel storage facility is not needed. There is increased reliability of operation. Nuclear power plants are not affected by adverse weather conditions. Nuclear power plants are well suited to meet large power demands. They give better performance at higher load factors (80-90%). Materials expenditure on metal structures, piping, storage mechanisms are much lower for a nuclear power plant than a coal burning power plant. It does not require large quantity of water. The generation of electricity through nuclear energy reduces the amount of energy generated from fossil fuels (coal and oil). Less use of fossil fuels means lowering greenhouse gas emissions (CO2 and others). Currently, fossil fuels are consumed faster than they are produced, so in the next future
these resources may be reduced or the price may increase becoming inaccessible for most of the population.
Disadvantages of Nuclear Power Plant Initial cost of nuclear power plant is higher as compared to hydro or steam power plant. Nuclear power plants are not well suited for varying load conditions. Radioactive wastes if not disposed carefully may have bad effect on the health of workers and other population. Maintenance cost of the plant is high.
It requires highly trained personnel to handle nuclear power plants. Nuclear power plants generate external dependence. Not many countries have uranium
mines and not all the countries have nuclear technology, so they have to hire both things overseas. Nuclear power plants are objectives of terrorist organizations. Decommissioning of nuclear power stations is expensive and takes a long time.
Conclusion: Widely used nuclear energy can be of great benefit for mankind. It can bridge the gap caused by inadequate coal and oil supply. It should be used to as much extent as possible to solve power problem. With further developments, it is likely that the cost of nuclear power stations will be lowered and that they will soon be competitive. With the depletion of fuel reserves and the question of transporting fuel over long distances, nuclear power stations are taking an important place in the development of the power potentials of the nations of the world today in the context of” the changing pattern of power. Nuclear accidents can spread 'radiation producing particles' over a wide area, This radiation harms the cells of the body which can make humans sick or even cause death. Illness can appear or strike people years after they were exposed to nuclear radiation and genetic problems can occur too. A possible type of reactor disaster is known as a meltdown. In a meltdown, the fission reaction of an atom goes out of control, which leads to a nuclear explosion releasing great amounts of radioactive particles into the environment. Chernobyl and Fukushima are the worst nuclear accidents to date causing many lives and leakage of radiation.
