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Q. Write an essay on nuclear power plant and the sources of waste generation in it.(R.GP.V., June 2014)
Ans. A nuclear power plant converts the nuclear energy of radioactive material into electrical energy. A nuclear power plant consists of a nuclear reactor, heat exchanger, steam turbine, alternator, condenser and various pumps as shown in fig. 1.12.
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Wastes from Nuclear Power Plant -Radioactive materials which are released into the environment mainly through nuclear power plants and nuclear explosions are responsible for nuclear pollution. These radioactive materials are highly carcinogenic and lethal to human, animal and plants. This dangerous pollution enters into the environment through waste streams and stack gases of nuclear power plants. Once these radio-elements access into the environment, they enter the ecocycling processes and ultimately into food chain and metabolic pathways. The radioactive waste from nuclear power plants may be in the form of gases, liquids or solids. Radioactive waste contains a number of radio nuclides such as strontium-90, jodine-131, iodine-129, caesium-137 and isotopes of iron and several other radioactive substances. Besides these radioactive materials, various kinds of radiations are also emitted by the nuclear power plants.
Sources of nuclear pollution may be natural or anthropogenic. Natural sources include
(i) Solar rays
(ii) Environmental radiation
(iii) Radionuclide in earth's crust.
The anthropogenic sources of nuclear pollution are from
(i) Nuclear power plants and reactors.
(ii) Mining and processing of ores to produce radio isotopes.
(iii) Radioactive fallout from nuclear weapons.
(iv) Emissions resulted from tests of nuclear weapons.
(v) Leakage from the nuclear testing laboratories.
(vi) Using radio isotopes in medicines, industries and agricultural operations.
Q. What is nuclear energy? Discuss Indian nuclear energy programme. (R.GP.V., Dec. 2015)
OrWhat is nuclear energy? Discuss its potential and utilization in India. (R.GP.V., June 2009, Dec. 2010)
Ans. Nuclear Energy - Refer Q.10 section (iii).
Indian Prospects - In India there are considerable resources of nuclear fuel. India having 70000 tonnes of uranium, if used in pressurised heavy water reactors (PHWRs) to generate electricity it can generate about 10 to 15 GWe for a period of thirty years. Plutonium and depleted uranium discharged from these PHWRS, if used in fast breeder reactors (FBRS), they can increase our installed capacity upto 300-350 GWe. India also has large deposits of fissionable material-thorium, which can eventually be used for power generation.
Late Dr. J.H. Bhabba, recognised the importance of nuclear energy and introduced a 3-stage nuclear energy programme for the development of nuclear power in the country.
Stage I-Construction of natural uranium fuelled reactors, using heavy water as moderator and coolant to produce electricity and a fissionable material plutonium (Pu23)
Stage II-Construction of fast breeder reactors, which utilises plutonium
and depleted uranium, the by-products of first stage. These FBRS produce
more fuel than they consume while supplying electricity. They will also produce
U233 from thorium, used as a blanket material.
Stage III - U233 will be used as fuel and thorium as blanket, producing more U233 fuel than consumed in fast and thermal reactors. At present there are 5 nuclear power plants in operation in India.
India's first nuclear power plant with a capacity of 420 MWe has been commissioned at Trapur (Maharashtra). It consists of two BWRS each of 210 MWe capacity. It uses enriched uranium (1.5-2.5%) as fuel and ordinary water as coolant and moderator. Due to stoppage of supply of enriched uranium from U.S.A. Indian scientists developed a mixed oxide (MOX) fuel to keep the plant running. MOX is a mixture of oxides of uranium and plutonium, fabricated indigeneously by our scientists.
Second nuclear power plant was installed at Rana Pratap Sagar, Kota (Rajasthan). It consists of two units of 220 MWe each, which works on CANDU principle. This is a horizontal pressure tube reactor using natural uranium as fuel, low pressure heavy water as moderator and high pressure heavy water as coolant. The third nuclear power plant was installed at Kalpakkam (Chennai), which
has two fast breeder reactors each of 235 MWe capacity and will use natural uranium as fuel. The fast breeder reactor with a design capacity of 40 MW thermal and 13 MW electrical attained its first criticality on 18 October 1985 With the commissioning of FBR, we have entered in the second stage of nuclear energy programme. Fourth nuclear power plant of India established at Narora, have two units of 235 MWe each and provision has been made to expand its capacity to 500
MWe. It works on CANDU-PHWR system and used natural uranium as fuel. The Kakarpara nuclear power plant in Gujrat is the fifth nuclear power plant of India, which have four reactors of 235 MWe each, out of which two already have been commissioned.
India also recognised the need of reprocessing the irradiated fuel to separate out the radioactive fission products and to recover plutonium and depleted uranium. It also established a 30 tonne/annum capacity reprocessing plant at Trombay and a 100 tonne/annum capacity plant at Tarapur.
Thus, now we can say India has the capacity of total fuel cycle, i.e., from exploring and mining of uranium, fabrication of various nuclear fuel elements, design construction and operation of PHWRS, production of heavy water, reprocessing of irradiated fuel to recover plutonium for use in FBRs and radioactive waste management.
Ans. Nuclear Energy - Refer Q.10 section (iii).
Indian Prospects - In India there are considerable resources of nuclear fuel. India having 70000 tonnes of uranium, if used in pressurised heavy water reactors (PHWRs) to generate electricity it can generate about 10 to 15 GWe for a period of thirty years. Plutonium and depleted uranium discharged from these PHWRS, if used in fast breeder reactors (FBRS), they can increase our installed capacity upto 300-350 GWe. India also has large deposits of fissionable material-thorium, which can eventually be used for power generation.
Late Dr. J.H. Bhabba, recognised the importance of nuclear energy and introduced a 3-stage nuclear energy programme for the development of nuclear power in the country.
Stage I-Construction of natural uranium fuelled reactors, using heavy water as moderator and coolant to produce electricity and a fissionable material plutonium (Pu23)
Stage II-Construction of fast breeder reactors, which utilises plutonium
and depleted uranium, the by-products of first stage. These FBRS produce
more fuel than they consume while supplying electricity. They will also produce
U233 from thorium, used as a blanket material.
Stage III - U233 will be used as fuel and thorium as blanket, producing more U233 fuel than consumed in fast and thermal reactors. At present there are 5 nuclear power plants in operation in India.
India's first nuclear power plant with a capacity of 420 MWe has been commissioned at Trapur (Maharashtra). It consists of two BWRS each of 210 MWe capacity. It uses enriched uranium (1.5-2.5%) as fuel and ordinary water as coolant and moderator. Due to stoppage of supply of enriched uranium from U.S.A. Indian scientists developed a mixed oxide (MOX) fuel to keep the plant running. MOX is a mixture of oxides of uranium and plutonium, fabricated indigeneously by our scientists.
Second nuclear power plant was installed at Rana Pratap Sagar, Kota (Rajasthan). It consists of two units of 220 MWe each, which works on CANDU principle. This is a horizontal pressure tube reactor using natural uranium as fuel, low pressure heavy water as moderator and high pressure heavy water as coolant. The third nuclear power plant was installed at Kalpakkam (Chennai), which
has two fast breeder reactors each of 235 MWe capacity and will use natural uranium as fuel. The fast breeder reactor with a design capacity of 40 MW thermal and 13 MW electrical attained its first criticality on 18 October 1985 With the commissioning of FBR, we have entered in the second stage of nuclear energy programme. Fourth nuclear power plant of India established at Narora, have two units of 235 MWe each and provision has been made to expand its capacity to 500
MWe. It works on CANDU-PHWR system and used natural uranium as fuel. The Kakarpara nuclear power plant in Gujrat is the fifth nuclear power plant of India, which have four reactors of 235 MWe each, out of which two already have been commissioned.
India also recognised the need of reprocessing the irradiated fuel to separate out the radioactive fission products and to recover plutonium and depleted uranium. It also established a 30 tonne/annum capacity reprocessing plant at Trombay and a 100 tonne/annum capacity plant at Tarapur.
Thus, now we can say India has the capacity of total fuel cycle, i.e., from exploring and mining of uranium, fabrication of various nuclear fuel elements, design construction and operation of PHWRS, production of heavy water, reprocessing of irradiated fuel to recover plutonium for use in FBRs and radioactive waste management.
Q. Briefly explain the nuclear fission and nuclear fusion. State the differences between them. (R.GP.V., June 2012, 2016)
Ans. Nuclear Fission - Nuclear fission is a neutron induced nuclear reaction in which a heavy nucleus such as uranium divides into two intermediate lighter nuclei. This fission of the nucleus produces two or rarely three fragments moving at high speeds, two or three neutrons and considerable amount energy.
Only certain heavy nuclei can undergo fission and the probability of fission reaction for a particular nucleus depends on the energy of incedenting neutrons Nuclei with odd number of neutrons, U233, U235 and U239, undergo fission with slow neutrons, while nuclei with even number of neutrons such as Th requires fast moving electrons.
Nuclear Fusion - Nuclear fusion is the process of combining two lighter
nuclei into a heavier nucleus. Mass of the nucleus formed in this process is
less than the total mass of original nuclei. This loss of mass get converted into energy. Nuclear fusion of 4 hydrogen atoms generates about 26.7 MeV of energy. This process is a thermo nuclear process like one which takes place in Sun and Hydrogen bomb.
4,H→He+2,e + 26.7 MeV
Ans. Nuclear Fission - Nuclear fission is a neutron induced nuclear reaction in which a heavy nucleus such as uranium divides into two intermediate lighter nuclei. This fission of the nucleus produces two or rarely three fragments moving at high speeds, two or three neutrons and considerable amount energy.
Only certain heavy nuclei can undergo fission and the probability of fission reaction for a particular nucleus depends on the energy of incedenting neutrons Nuclei with odd number of neutrons, U233, U235 and U239, undergo fission with slow neutrons, while nuclei with even number of neutrons such as Th requires fast moving electrons.
Nuclear Fusion - Nuclear fusion is the process of combining two lighter
nuclei into a heavier nucleus. Mass of the nucleus formed in this process is
less than the total mass of original nuclei. This loss of mass get converted into energy. Nuclear fusion of 4 hydrogen atoms generates about 26.7 MeV of energy. This process is a thermo nuclear process like one which takes place in Sun and Hydrogen bomb.
4,H→He+2,e + 26.7 MeV
Differences between Nuclear Fission and Nuclear Fusion
The differences between nuclear fission and nuclear fusion are given below in
Nuclear Fission
(a) It is a process of breaking a heavy nucleus into two or more light fragments, with the liberat- ion of large amount of energy.
(b) During fission, neutrons are emitted.
(c) The mass number and atomic number of resulting elements are lower than that of the original element.
(d)It takes place at ordinary temperatures.
(e) It can be performed under controlled conditions.
(f)It results in emission of radioactive rays and other hazardous substances.
Nuclear Fission
It is a process of joining two light nuclei into a single nucleus with the liberation of a large amount of energy.
During fusion, protons are emitted.
The mass number and atomic number of resulting element is higher than that of the starting elements.
It takes place at very high temp- erature about 108 °C.
It cannot be performed under controlled conditions.
The end product is helium which is harmless.
The differences between nuclear fission and nuclear fusion are given below in
Nuclear Fission
(a) It is a process of breaking a heavy nucleus into two or more light fragments, with the liberat- ion of large amount of energy.
(b) During fission, neutrons are emitted.
(c) The mass number and atomic number of resulting elements are lower than that of the original element.
(d)It takes place at ordinary temperatures.
(e) It can be performed under controlled conditions.
(f)It results in emission of radioactive rays and other hazardous substances.
Nuclear Fission
It is a process of joining two light nuclei into a single nucleus with the liberation of a large amount of energy.
During fusion, protons are emitted.
The mass number and atomic number of resulting element is higher than that of the starting elements.
It takes place at very high temp- erature about 108 °C.
It cannot be performed under controlled conditions.
The end product is helium which is harmless.
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