• Nuclear physics is the field of physics that studies the constituents and interactions of atomic nuclei. The most commonly known applications of nuclear physics are nuclear power generation and nuclear weapons This chapter explains the fundamentals of nuclear power generation through nuclear reactors, various types of reactors and India’s nuclear power programme. Let us start with understanding Nuclear Fission, Nuclear Fusion and Nuclear fuels.


  • Nuclear Fission
    • Nuclear fission is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts (lighter nuclei) often producing free neutrons and protons(in the form of gamma rays) and

releasing a very large amount of energy, even by the energetic standards of radioactive decay.

3.2.2 Nuclear Fusion

  • Nuclear fusion is a process by which two or more lighter nuclei fuse to form a single heavier nucleus.

3.2.3 Nuclear chain reaction

  • Fission is manmade nuclear reaction induced by a neutron. Nuclear fission produces energy for nuclear power and to derive explosion of nuclear weapons, certain substances called nuclear fuels undergo fission when struck by fission neutrons in turn omit neutrons when they break
  • This makes possible a self- sustaining nuclear chain reaction that releases energy at a controlled rate in a nuclear reactor or at a very rapid uncontrolled rate in a nuclear weapon.

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  • Nuclear fuel is a material that can be ‘burned’ by nuclear fission or fusion to derive nuclear energy. Nuclear fuel can be categorised into fissile and fissionable material. Fissile material is one that is capable of sustaining a nuclear chain reaction of nuclear fission and releases nuclear energy.

(E.g.) Plutonium (Pu)

  • Natural Uranium (U-238)
  • Enriched Uranium (U-235)
  • Thorium derived  Uranium (U-233)

3.3.1 Plutonium (Pu)

  • Atomic no. 94
  • A transuranic element (Any element which has atomic number greater than 92)
  • It does not occur in nature
  • It is man-made in nuclear reactors by conversion of Uranium into PU, by a process of neutron-irradiation (activation- induced radio activity in material).

Plutonium is an ideal nuclear fuel because

  • It releases more nuclear energy per unit than any other nuclear material
  • It undergoes nuclear fission both in the fast- and slow-moving neutron
  • It has a higher breeding radio (average no of fission atoms created per fission event)
  • It releases less xenon gas which is radio-active and thus less poisonous than any other nuclear fuels.

Isotopes of Pu:

  • Plutonium occurs in two difference isotopes Pu-239 and Pu-240
  • If the concentration of Pu239 Isotope, in the Plutonium core is more than 90%, it is called weapon grade Plutonium. This is so because Plutonium undergoes nuclear fission more steadily and does not disintegrate too early. Thus it burns up a powerful blast and the nuclear energy yield is more
  • If the Pu240 Isotope concentration in Plutonium core is more, it is called reactor-grade Plutonium. Pu240 undergoes nuclear fission rapidly and crumbles too early. Therefore, it is used in nuclear reactors for power

3.3.2 Natural Uranium (U-238)

  • It is a poor nuclear
  • It undergoes nuclear fission only when bombarded by a fast- moving neutron. Therefore, it means very little or no moderator. If heavy water is used in such reactor, it is used primarily as coolant, but not as moderator.

3.3.3 Enriched Uranium (U-235)

  • It is an excellent nuclear
  • It undergoes nuclear fission only when bombarded by a slow moving neutron. Therefore, it needs the use of a moderator to slow down the speed of neutrons without capturing them. Enrichment of Uranium

  • Natural Uranium that is mined, contains up to 0.7% of the Isotope, U-2 The process of isolating U-235 isotopes is called enrichment of Uranium. It is done with the help of Ring Magnet (or) Nuclear Laser method.

Low Enriched Uranium (LEU):

  • If the concentration of U-235 Isotopes is the Uranium core is 4% or less, it is called LEU. It can be used in nuclear reactor for power

Highly Enriched Uranium (HEU):

  • If the concentration of U-235 Isotope is Uranium core is more than 20%, it is called HEU. For the manufacturing of nuclear weapons, we need a concentration of U-235, more than 80%.

3.3.4 Thorium derived Uranium (U-233)

  • It does not occur in nature
  • It is produced in a nuclear reactor by neutron irradiation
  • It is a good nuclear fuel that undergoes nuclear fission when bombarded by a fast moving electron.

3.3.5 Heavy Water

  • Chemically known as Deuterium Oxide.
  • It is ordinary water in which ordinary Hydrogen Isotopes are replaced by heavier Deuterium isotopes of
  • It is the most preferred moderator.
  • India has achieved self- sufficiency in the production of Heavy
  • Heavy water plants are in
    • Manuguru(AP),
    • Thal (Maharashtra),
    • Hazira(Gujarat),
    • Kota(Rajasthan),
    • Baroda(Gujarat),
    • Tuticorin (TN),
    • Nangal(Punjab),
    • Talcher(Orissa)


  • A nuclear reactor is a device used to initiate and control a sustained nuclear chain

The following are the essential components of a nuclear reactor

  • Fuel: The material containing fissile isotope is called reactor fuel. U235, Pu239 and U233 are used as fuel in the cylinder. The fuel is sealed in aluminium cylinder and kept in the form of rods. Natural uranium contains 99.28% of U238and only 0.72% of fissile U235.  The fissile U235 fuel is called enriched uranium.
  • Moderator: The moderator is a material which is used to slow down the neutrons produced by nuclear fission. Graphite, Heavy water (D20), Berillium and itsoxides are used as moderators. A good moderator should have high boiling point and low atomic number.
  • Control Rods: In order to control the chain reaction, control rods are used. These rods are made up of neutron absorbing materials. Cadmium, boron or Hafnium rods are used as control rods. When the control rod is completely pushed into the fuel, the neutrons are absorbed and hence the chain reaction stops. If the rods are withdrawn, stronger will be the chain reaction.
  • Coolant: A material used to absorb the heat generated in chain reaction is called coolant. The heat carried by coolant is used to convert water into steam which in turn runs the turbines to produce electricity. Ordinary water, heavy water, air, carbon- dioxide, helium gas and liquid sodium and are used as coolants. Heavy water serves both as moderator and as coolant. A pump is provided to pump the coolant into the reactor. The coolant should have high boiling point and high specific
  • Neutron reflector: Neutron reflector is a material surrounding the fuel and

moderator. It is used to reflect the escaping neutrons back into the reactor. This minimises the leakage of neutrons.

  • Shielding: The radiations emitted during nuclear fission reactions are very dangerous and harmful to living beings. To protect the people operating the reactor it is surrounded by thick lead lining and concrete wall of thickness about 2 to 2.5


  • Thermal Reactors
    • These reactors make use of slow moving neutron to bring about the nuclear fission reaction. It uses Plutonium (or) Enriched Uranium as the fuel and uses a moderator. It is resistant to proliferation of nuclear weapons and thus, the most commonly found nuclear reactors of the world.

3.5.2 Fast Reactors

  • It makes use of a fast moving neutron to bring about a nuclear chain reaction. It uses Plutonium
    or Natural Uranium or Thorium derived Uranium as its fuel and uses very little / no moderator.Indis’s indigenously developed fast reactors are at
  • RawatBhatta (Raj)
  • Kalpakkam (Tamil Nadu)
  • Narova (U.P.)
  • Kakrapur (Gujarat)
  • Kaiga (Karnataka)

3.5.3 Breeder Reactors

  • It produces more fissile material than it burns by converting a fissionable material into a fissible material. The Fast Breeder Reactors will be the core of the India’s nuclear power programme and all the 2nd General Nuclear reactors of India will be
  • The world’s only operational FBR, known as Fast breeder Test Reactor (FBTR) has been established by the Indra Gandhi Centre for Atomic Research (IGCAR), Kalpakkam. On the basis of the FBTR successful operation, IGCAR is at present engaged in the construction of a prototype FBR (PFBR) with 500 MW capacity at Kalpakkam, which  is expected to be commissioned by end of 2014.



  • It is formulated by HomiBhabha and it involves the development of 3 generations of nuclear reactors successively. It aims to make use of vast thorium deposits of

1st Generation reactors (PHWR):

  • These reactors have been initially designed to have a capacity of not more than 250 MW each. They are to be established at Rawatbhatta, Kalpakkam, Narora, Kakrapur & Kaiga. These reactors use natural uranium as the fuel and heavy water as the coolant. They are all, Pressurized Heavy Water Reactors (PHWR). They generate power and produce Plutonium as the by product. India has designed and established 540MW capacity 1stgeneration reactors and has drawn up plans to construct 700 MW capacity PHWR

2nd Generation Reactors (FBR):

  • They will be of 500 MW capacity of each. The 1st such reactors will be set up at Tarapur. They will be FBR. They will use Pu derived from the 1st Generation reactors as fuel and convert Thorium into U-2 They will use liquid sodium as coolant. The Prototype FBR is under development at Kalpakkam and our country has proposed to under take 4 FBRs during 12thfive year plan.

3rd       Generation   Reactors (Thermal breeder reactor):

  • They will be of 1000MW capacity of each and will use U-233 derived from 2nd reactors as the fuel and convert Thorium into more U-233. Thus the 3rdgeneration reactors will be Thorium cycle reactors. They will be cooled by light water (Demineralized water – water from which minerals are removed). They will be culmination of exploitation of vast Thorium resources in India.

3.6.1 Thorium deposits

  • Thorium deposits are found in the Monazite sands of Kerala, Tamil Nadu, Andhra Pradesh and Orissa. India has the largest Thorium deposits of the world, estimated to          be 5,00,000tones,whereas, the known Thorium deposits of India are likely to last for about 30 years.Thorium if exploited can provide energy security for India nearly 300

3.6.2 Spent Fuel

  • The remains of a nuclear fuel, obtained from a nuclear reactor, after the fuel has been burnt, is known as spent fuel. It is not entirely a waste. It contains useful, radio active substances, like Pu, Mixed Oxides of U (MOX), U-PU carbide fuel etc, of which Pu is the most important by product. These fuels can be subsequently used as fuels in nuclear
  • India set up its 1st reprocessing plant at Tarapur (1964) and became the 5th country in the world to develop nuclear reprocessing technique. The Tarapur reprocessing plant is called Power Reactor Fuel Reprocessing Plant (PREFRE). It has  capacity of 100 tonnes/annum.The 2nd reprocessing plant was set up in Trombay with 100 tonnes capacity. The 3rd  was KARP 125 Kalpakkam Reprocessing plant with 125 tonnes capacity. All the 3 plants are capable of isolating both PU-239 AND pu-240 Isotopes, strengthening India’s strategic and civilian nuclear programme.

3.6.3 Russian Reactors

  • On the basis of original agreement signed by India and former Soviet Union in 1988, Russia has been constructing 2 thermal reactors of 1000 MW capacity each at Koodankulam (Tamil Nadu). Under an agreement signed in October 2001. Russia will supply 90% of components, LEU as the fuel and heavy water as the moderator. The cost of the 2 reactors will be $2 billion. They will be constructed by Russia as a Turn- key project. Both the reactors will come under International Control.


  • It was formulated by Bhabha Atomic Research Centre, in 1 It aims to generate 20,000 MW of nuclear power by 2020, contributing 10% of the total power generated in the country. It shall be achieved by establishing indigenous and imported reactors.
  • India has a flourishing and largely indigenous Nuclear Power Programme and expects to have 14,600 MW Nuclear capacity on line by Nuclear Power Corporation of India Ltd (NPCIL) is the public sector company which owns, constructs and operates nuclear power plants in India. NPCIL has a plan to put up a total installed nuclear power capacity of 63,000 MWe (Megawatt energy) by the year 2032. India’s nuclear power programme has 14 reactors in
    operation and eight power reactors under construction.
  • It aims to supply 25% of electricity from Nuclear Power Programme. Because India is outside the Nuclear Non Proliferation Treaty (NPT) due to weapons programme, it was for

34  years  largely  excluded  from trade in Nuclear Plant or materials,  which  has  hampered tis development  in civil Nuclear energy until 2009.

  • Due to these trade bans and lack of indigenous Uranium, India has uniquely been developing a

nuclear fuel cycle to exploit its reserves of Thorium. India has a vision of becoming a world leader in nuclear technique due to its expertise in fast reactors and thorium fuel cycle.

  • As of 2015, India has 21 nuclear reactors in operation in six nuclear power plants, generating 5780 MW. Some important operating nuclear power reactors and power reactors which are under construction are shown in the tables


Power station OperatorStateTypeUnitsTotal capacity (MW)
KaigaKaiga Atomic Power Station (KAPS)NPCILKarnatakaPHWR220 x 4880
KakraparKakrapur Atomic Power Plant (KAPP)NPCILGujaratPHWR220 x 2440
KalpakkamIndira Gandhi Atomic Research Centre (IGCAR)NPCILTamil NaduPHWR220 x 2440
NaroraNarora Atomic Power Plant (NAPP)NPCILUttar PradeshPHWR220 x 2440
RawatbhataRajasthan Atomic power station (RAPS)NPCILRajasthanPHWR100 x 1
200 x 1
220 x 4
TarapurTarapur Atomic Power Station (TAPS)NPCILMaharashtr aBWR (PHW R)160 x 2
540 x 2
KudankulamNPCILTamil NaduVVER-10001000 x 22000


Power stationOperatorStateTypeUnitsTotal capacity (MW)
KalpakkamBhaviniTamil NaduPFBR500 x 1500
KakraparNPCILGujaratPHWR700 x 21400
RawatbhataNPCILRajasthanPHWR700 x 21400

  • The reactor is been constructed at Kalpakkam by Indira Gandhi Centre for Atomic Research (IGCAR). It has been designed and developed on the basis of successful operation of Fast Breeder Test Reactor since 1
  • The PFBR will be a 500 MW capacity facility and cost about Rs.3500 Crores. It will use Plutonium – Uranium Oxide as fuel and liquid sodium as Coolant. Its construction started in 2004 and is expected to commission in 2014. India is the only country in the World that is actively engaged in the research and development of fast breeder reactors  and  the  conversion  of Thorium into U-235. In order to manage  the  PFBR  Project,  the Atomic Energy Commission has given the responsibility to BhartiyaNabhikiyaVidyut  Nigam Ltd.  (BHAVINI). The  PFBR will be  a  major  technological development for Department of Atomic Energy and is compared to IGMDP, LCA Programme and Nuclear Submarine Programme.
  • The development of breeder technology will help in converting Thorium in to U-233, but will also be multiply/amplify energy from natural Uranium manyfold, by converting about 70% of non- fissile Uranium to fissile Plutonium.
  • The FBR technology is to achieve energy security and be self- sufficient in the area of nuclear fuel. It is estimated that the thorium deposits of India can help in generating 5 GW of nuclear energy in the next 50-100 years.

Other advantages of Fast Breeder Technology:

  • A FBR increases fuel utilisation by about 60 times of what is possible in a Pressurized
  • It helps in generating electricity and building up nuclear fuel inventory in the form of Uranium-233 and
  • The radio activity that is released into atmosphere is less as compared to other types of reactors.


  • Nuclear Suppliers Group is a group of nuclear supplier countries which seek to contribute to the non- proliferation of nuclear weapon through the implement of guidelines for nuclear exports and nuclear related
  • Originally known as London Club, it was set up as an adhoc body in 1975 by7 countries, namely USA, Former Soviet Union, United Kingdom, France, Canada, Germany and Japan. At present, it consist of 46 members, all of them are parties to NPT. The notable non-members of Nuclear Suppliers Group are India, Israel & Pakistan. It was established to tighten export control to ensure that the nuclear facilities and materials are sold exclusively for peaceful use, were not diverted for military purposes. The guidelines of the NSG originally prohibited its member countries to export nuclear fuel, nuclear components or nuclear reactors to any country that refused to accept international safeguards under International Atomic energy Association (IAEA) supervision over the nuclear material supplied to ensure that the imported nuclear material/ nuclear facilities were not misused for military purposes. Thus the guidelines initially demanded that the reactor specific safeguards shall be accepted by the receiving country.
  • In 1992, the Nuclear Suppliers Group introduced 2 major changes in its guidelines. The first change demands that the receiving country shall accept full scope safeguards under which it would place all its nuclear facilities including its indigenous facilities under international safeguards. The second change imposed more stringent controls over dual use items which lead to IAEA implementing on its members, a more stringent

control known as Additional Protocol. While India is prepared to accept the additional protocol and reactor-specific safeguards, it is not ready to accept full scope safeguard as it would amount to signing the NPT through the back-door.

  • The Indo-US Civilian Nuclear Programme aims to relax the Nuclear Suppliers Group guidelines so that India-specific waiver is made by the Nuclear Suppliers Group in its guidelines and India will be allowed to enter into nuclear trade with the members of Nuclear Suppliers Group. However, all decisions to Nuclear Suppliers Group are taken on consensual

3.9.1 Additional Protocol:

  • All the members of NPT are under an obligation to sign the additional protocol formulated by the IAEA, under which the IAEA will have the right to carry out unannounced and intrusive inspection on the Nuclear facilities of the member countries.


  • It is one of the related bodies of UN, established in 1957 and thehead quarters is in Vienna.Theresponsibilities of IAEA are
  • To assist countries in harnessing nuclear energy for peaceful purposes.
  • To carryout inspections to ensure that any nuclear assistance, one country received from another is used exclusively for peaceful purposes and not diverted for weapons
  • The Non-nuclear weapon states that are members of Nuclear Power Plant are under an obligation to place all their nuclear facilities under IAEA inspection. This is to ensure that no nuclear fuel is diverted by a have-not country for military purposes. Thus, the IAEA is mainly concerned with regulatory aspects in the field of nuclear science and is an instrument of nuclear non-proliferation.
  • India is the member of the executive council of IAEA. On the basis of the Indo-US civilian nuclear agreement, India has successfully concluded a India- specific safety agreement with IAEA in July 2 This is one of the requirements India had to accomplish for the nuclear deal to become operational.


  • It is a non-governmental body of nuclear operators found after the Chernobyl Nuclear Accident (1986).
  • Established in 1989
  • Based in London
  • Main function – domain of safety of reactor
  • It certifies safety aspect of nuclear reactors that are open to inspection. India had voluntarily agreed to place the 2 nuclear reactors each at Kakrapur and Narora for peer review of
  • Indian Nuclear Scientists took part in peer reviews held in USA, Japan and South Korea. This helps them to implement similar safety aspects in Indian Nuclear facilities. Experts from 33 countries are represented in WANO including India.


  • Nuclear fusion is a nuclear reaction between light atomic nuclei as a result of which a heavier nucleus is formed and enormous quantity of nuclear energy is released. For the fusion to be possible, the reacting nuclei must possess sufficient kinetic energy to overcome the repulsive force between them. Therefore, the temperature that is associated with fusion reaction is of billions of degree

The advantages of fusion reaction over fission reaction are

  • Fusion reaction is almost free from radio-active fallout. There is no associated problem of disposal of radioactive fuel. Thus, it is a clean form of
  • The nuclear fuel needed for fusion process is available in plenty in the form of sea Therefore, it is a nearly inexhaustible source of energy.
  • A fusion reactor, by its very design nature can never explode. If any accident takes place, the critical temperature will fall and fusion reaction will come to an end.

3.12.1 Nuclear Fusion Reactor

  • A fusion reactor is built on the basis of TOKOMAK It is a Russian acronym for Toroidal Magnetic Chamber. It was designed by the Soviet Scientist, Lex Art Simorich in 1967. A TOKOMAK is enclosed by powerful magnets which by repulsive force keep the atomic nuclei that are in a state of plasma within the confines of the chamber, without coming into physical contact of the plasma. This helps in not only containing the plasma within the chamber, but also in maintaining the high temperature above the critical level which is essential for igniting and sustaining the fusion reaction.

3.12.2 Fusion Research in India:

  • Fusion research has been going on Tata Institute of Fundamental research (TIFR), Bhabha Atomic research Centre (BARC), Saha Institute of Nuclear Physics, Kolkata. Physical Research Laboratory, Ahmedabad. The research PRL led to the establishment of Institute for Plasma Research (IPR) at Russia, Japan, China, South Korea, India, Europe& USA.  The reactor is constructed under the supervision of  IAEA. It  is being constructed at Cadarache in South France. It is expected to start the 1st  Plasma Operation in 2020. A commercial fusion reactor is expected to be ready for power generator in 2050. increase the plasma confining time. Therefore, the SST-1 also forms  the  basis  of  the  ITER International Thermonuclear Experimental Reactor design. India has ultimately been admitted to ITER in December
  1. The ITER Project includes at present 7 countries, namely
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