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A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate, as opposed to a nuclear bomb, in which the chain reaction occurs in a fraction of a second and is uncontrolled causing an explosion.
The most significant use of nuclear reactors is as an energy source for the generation of electrical power and for the power in some ships . This is usually accomplished by methods that involve using heat from the nuclear reaction to power steam turbines. There are also other less common uses as discussed below.
Nuclear Energy is released by the splitting (fission) or merging together (fusion) of the nuclei of atom.
The conversion of nuclear mass to energy is consistent with the mass-energy equivalence formula Î”E = Î”m.cÂ², in which Î”E = energy release, Î”m = mass defect, and c = the speed of light in a vacuum .
Nuclear energy was first discovered by French physicist Henri Becquerel in 1896.
TYPES OF NUCLEAR REACTIONS
There is two types of nuclear reactions from which nuclear energy is formed:
Nuclear fusion reactions
Nuclear fission reactions
Nuclear fusion reaction:-It is the procees by which multiple like-charged atomic nuclei join together to form a heavier nucleus.It is accompanied by the release or absorption of energy.Iron and nickel nuclei have the largest binding energies per nucleon of all nuclei. The fusion of two nuclei with lower mass than iron generally releases energy while the fusion of nuclei heavier than iron absorb energy ,vice versa for the reverse procees (nuclearfission).
Nuclear Fusion Power
Nuclear fusion reactors, if they can be made to work, promise virtually unlimited power for the indefinite future. This is because the fuel, isotopes of hydrogen, are essentially unlimited on Earth. Efforts to control the fusion process and harness it to produce power have been underway in the United States and abroad for more than forty years.
Nuclear fusion is the source of energy in the sun and stars where high temperatures and densities allow the positively-charged nuclei to get close enough to each other for the nuclear force to overcome the electricalforce and allow fusion to occur
3H + 2H Æ 4He + n + 17.6 MeV
involves the radioactive nuclide tritium ( 3H), available from the nuclear production reaction
6Li + n Æ 3H + 4He.
To produce energy using this reaction, both the magnetic confinement reactor with a high temperature plasma (a gas that has been completely ionized) and the inertial confinement reactor (which utilizes laser implosion technologies) have been investigated. Extremely high plasma temperatures are required in the magnetic confinement reactor and difficult laser implosion techniques are required for the inertial confinement reactor. Although significant progress has been made in these investigations, no working reactor that produces more energy than it consumes has been built. Unfortunately, the funding for continuing this work has declined, and the work is proceeding at a slower pace.
Although these types of reactors would not have the fission product waste disposal problem of fission reactors, fusion reactors generate large number of fast neutrons, leading to large quantities of radioactive byproducts.
Another approach to nuclear fusion-an approach that could lead to aneutronic power (power without neutrons) and non-radioactive nuclear energy-uses the concept of colliding-beam fusion (CBF). One aneutronic method features the 2H + 3He reaction leading to the products 1H + 4He. However, this requires 3He as fuel and terrestrial sources of this are limited. The Moon is a potential source of 3He produced by cosmic-ray protons hitting the Moon directly and not being absorbed by an atmosphere as on Earth. Another potential approach for colliding beam fusion is the 11B + 1H reaction leading to the three 4He nuclei. The energy release is in the form of charged particles whose kinetic energy can be converted to electricity with a very high efficiency. Current research predicts that this energy source has an extremely high degree of cleanness and efficiency. In all current energy sources, approximately two-thirds of the energy is lost in the form of waste heat or thermal pollution. In the CBF approach, there is virtually no waste. This design favors small size for the greatest efficiency (100 MWe or less), and would lead to either power plants with several reactors or decentralization of energy production.
A nuclear weapon or nuclear bomb is a type of weapon of mass destruction and an explosive device that derives its destructive force from nuclear reactions . Both reactions release vast quantities of energy from relatively small amounts of matter; a modern thermonuclear weapon weighing little more than a thousand kilograms can produce an explosion comparable to the detonation of more than a billion kilograms of conventional high explosive. Even small nuclear devices with yields equivalent to several thousand tons of TNT can devastate a city. Nuclear weapons are considered weapons of mass destruction, and their use and control has been a major aspect of international policy since their debut in Nagasaki and Hiroshima
Fusion bomb, hydrogen bomb (H-bomb), or thermonuclear weapon/bomb
The second basic type of nuclearweapon produces a large amount of energy through nuclear fusion reactions. These weapons are called fusion bombs or thermonuclear weapons/bombs. They have also been called hydrogen bombs, as they formed on fusion reactions between isotopes of hydrogen (deuterium and tritium), though all such weapons derive a significant-and sometimes a majority-of their energy from fission reactions . Because fusion material cannot go overcritical no matter the amount used, and because fusion weapons can be staged, these kind of weapons may be made
significantly more powerful than fission bombs.
Nuclear Fission reactions:-Nuclear fission is the splitting of the bigger nucleus into two smaller nuclei with release of neutrons and energy.
Fission of heavy elements is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments.Fission is a form of elemental transmutation.
The amount of energy contained in nuclear fuel is millions the amount of free energy contained in a gasoline,making nuclear fission a very tempting source of energy.however the products of nuclear fission are radioactive and remain so for significant amounts of time,giving rise to a nuclear waste problem.
Nuclear fission differs from other forms of radioactive decay in that it can be harnessed and controlled via a chain reaction.Chemical isotopes that can sustain a fission chain reaction are called nuclear fuels,and are said to be fissile.The most comman nuclear fuels are U-235 and Pu-239.Most nuclear fuels undergo spontaneous fission only very slowly ,decaying mainly via an alpha/beta decay chain over periods.In a nuclear reactor or nuclear weapons,most fission events are induced by bombardment with another particle such as a neutron.
Fission bomb or atomic/atom bomb (A-bomb)
The first basic type of nuclear weapon produces explosive energy through nuclear fission reactions alone. These weapons are called fission bombs. They have also been called atomic/atom bombs (or A-bombs) since their first use, though their energy comes specifically from the nucleus of the atom.
In fission weapons, a mass of fissile material is assembled into a supercritical mass-the amount of material needed to start an exponentially growing nuclear chain reaction-either by shooting one piece of sub-critical material into another or by using chemical explosives to compress a sub-critical sphere of material to many times its original density. The latter approach is considered more sophisticated than the former, and only the latter approach can be used if plutonium is the fissile material.
A major challenge in all nuclear weapon designs is to ensure that a significant fraction of the fuel is consumed before the weapon destroys itself.
Applications of Nuclear Technology
Fission Nuclear power is a type of nuclear technology involving the controlled use of nuclear to release energy for work including propulsion, heat, and the generation of electricity. Nuclear energy is produced by a controlled nuclear chain reaction which creates heat-and which is used to boil water, produce steam, and drive a steam turbine. The turbine is used to generate electricity and/or to do mechanical work.
The medical applications of nuclear technology are divided into diagnostics and radiation treatment.
Imaging - medical and dental x-ray imagers use of Cobalt-60 or other x-ray sources. Positron emitting nucleotides are used for high resolution, short time span imaging in applications known as Positron emission tomography.
Radiation therapy is an effective treatment for cancer.
Oil and Gas Exploration- Nuclear well logging is used to help predict the commercial viability of new or existing wells. The technology involves the use of a neutron or gamma-ray source and a radiation detector which are lowered into boreholes to determine the properties of the surrounding rock such as porosity and lithography.
Food Processing and Agriculture
The HYPERLINK "../../../../../../wiki/Radura"Radura logo, used to show a food has been treated with ionizing radiation.
Food irradiation is the process of exposing food to ionizing radiation in order to destroy microorganisms, bacteria, viruses, or insects that might be present in the food. The radiation sources used include radioisotope gamma ray sources, X-ray generators and electron accelerators. As such it is also used on non-food items, such as medical hardware, plastics, tubes for gas-pipelines, hoses for floor-heating, shrink-foils for food packaging, automobile parts, wires and cables, tires, and even gemstones. Compared to the amount of food irradiated, the volume of those every-day applications is huge but not noticed by the consumer.
The genuine effect of processing food by ionizing radiation relates to damages to the DNA, the basic genetic information for life. Micro-organisms can no longer proliferate and continue their malignant or pathogen activities. Spoilage causing micro-organisms cannot continue their activities. Insects do not survive or become incapable of procreation. Plants cannot continue the natural ripening or aging process. All these effects are beneficial to the consumer and the food industry. Food irradiation is currently permitted by over 40 countries and volumes are estimated to exceed 500â€‰000 metric tons annually world wide
When a relatively large fissile atomic nucleus (usually uranium-235 or plutonium-239) absorbs a neutron it is likely to undergo nuclear fission. The original heavy nucleus splits into two or more lighter nuclei also releasing kinetic energy, gamma radiation and free neutrons; collectively known as fission products. A portion of these neutrons may later be absorbed by other fissile atoms and trigger further fission events, which release more neutrons, and so on.
The nuclear chain reaction can be controlled by using neutron poisons and neutron moderators to change the portion of neutrons that will go on to cause more fissions. In nuclear engineering, a neutron moderator is a medium which reduces the velocity of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235.
Commonly used moderators include regular (light) water (75% of the world's reactors), solid graphite (20% of reactors) and heavy water (5% of reactors). Beryllium has also been used in some experimental types, and hydrocarbons have been suggested as another possibility. Increasing or decreasing the rate of fission will also increase or decrease the energy output of the reactor.
It is a type of nuclear reaction in which two daughter nuclei combine together to form a bigger nucleus.
The reactor core generates heat in a number of ways:
The kinetic energy of fission products is converted to thermal energy when these nuclei collide with nearby atoms.
Some of the gamma rays produced during fission are absorbed by the reactor in the form of heat.
Heat produced by the radioactive decay of fission products and materials that have been activated by neutron absorption. This decay heat source will remain for some time even after the reactor is shutdown.
The heat power generated by the nuclear reaction is 1,000,000 times that of the equal amount of coal.
A cooling source - often water but sometimes a liquid metal - is circulated past the reactor core to absorb the heat that it generates. The heat is carried away from the reactor and is then used to generate steam. Most reactor systems employ a cooling system that is physically separate from the water that will be boiled to produce pressurized steam for the turbines, but in some reactors the water for the steam turbines is boiled directly by the reactor core.
The power output of the reactor is controlled by controlling how many neutrons are able to create more fissions.
Control rods that are made of a nuclear poison are used to absorb neutrons. Absorbing more neutrons in a control rod means that there are fewer neutrons available to cause fission, so pushing the control rod deeper into the reactor will reduce its power output, and extracting the control rod will increase it.
In some reactors, the coolant also acts as a neutron moderator. A moderator increases the power of the reactor by causing the fast neutrons that are released from fission to lose energy and become thermal neutrons. Thermal neutrons are more likely than fast neutrons to cause fission, so more neutron moderation means more power output from the reactors. If the coolant is a moderator, then temperature changes can affect the density of the coolant/moderator and therefore change power output. A higher temperature coolant would be less dense, and therefore a less effective moderator.
In other reactors the coolant acts as a poison by absorbing neutrons in the same way that the control rods do. In these reactors power output can be increased by heating the coolant, which makes it a less dense poison.
Nuclear reactors generally have automatic and manual systems to insert large amounts of poison (boron) into the reactor to shut the fission reaction down if unsafe conditions are detected.
NUCLEAR POWER GENERATION:
Most reactors, and all commercial ones, are based on nuclear fission. They generally use uranium as fuel, but research on using thorium is ongoing (an example is the liquid fluoride reactor). This article assumes that the technology is nuclear fission unless otherwise stated. Fission reactors can be divided roughly into two classes, depending on the energy of the neutrons that are used to sustain the fission chain reaction:
Thermal reactors use slow or thermal neutrons. Most power reactors are of this type. These are characterized by neutron moderator materials that slow neutrons until they approach the average kinetic energy of the surrounding particles, that is, until they are thermalized. Thermal neutrons have a far higher probability of fissioning uranium-235, and a lower probability of capture by uranium-238 than the faster neutrons that result from fission. As well as the moderator, thermal reactors have fuel (fissionable material), containments, pressure vessels, shielding, and instrumentation to monitor and control the reactor's systems.
Fast neutron reactors use fast neutrons to sustain the fission chain reaction. They are characterized by an absence of moderating material. Initiating the chain reaction requires enriched uranium (and/or enrichment with plutonium 239), due to the lower probability of fissioning U-235, and a higher probability of capture by U-238 (as compared to a moderated, thermal neutron). Fast reactors have the potential to produce less transuranic waste because all actinoids are fissionable with fast neutrons, but they are more difficult to build and more expensive to operate. Overall, fast reactors are less common than thermal reactors in most applications. Some early power stations were fast reactors, as are some Russian naval propulsion units. Construction of prototypes is continuing (see fast breeder or generation IV reactors).
Nuclear fusion. Fusion power is an experimental technology, generally with hydrogen as fuel. While not currently suitable for power production, Farnsworth-Hirsch fusors are used to produce neutron radiation.
Radioactive decay. Examples include radioisotope thermoelectric generators and atomic batteries, which generate heat and power by exploiting passive radioactive decay.
Future and developing technologies
More than a dozen advanced reactor designs are in various stages of development. Some are evolutionary from the PWR, BWR and PHWR designs above, some are more radical departures. The former include the Advanced Boiling Water Reactor (ABWR), two of which are now operating with others under construction, and the planned passively safe ESBWR and AP1000 units (see Nuclear Power 2010 Program).
The Integral Fast Reactor was built, tested and evaluated during the 1980s and then retired under the Clinton administration in the 1990s due to nuclear non-proliferation policies of the administration. Recycling spent fuel is the core of its design and it therefore produces only a fraction of the waste of current reactors.
The Pebble Bed Reactor, a High Temperature Gas Cooled Reactor (HTGCR), is designed so high temperatures reduce power output by doppler broadening of the fuel's neutron cross-section. It uses ceramic fuels so its safe operating temperatures exceed the power-reduction temperature range. Most designs are cooled by inert helium. Helium is not subject to steam explosions, resists neutron absorption leading to radioactivity, and does not dissolve contaminants that can become radioactive. Typical designs have more layers (up to 7) of passive containment than light water reactors (usually 3). A unique feature that may aid safety is that the fuel-balls actually form the core's mechanism, and are replaced one-by-one as they age. The design of the fuel makes fuel reprocessing expensive.
SSTAR, Small, Sealed, Transportable, Autonomous Reactor is being primarily researched and developed in the US, intended as a fast breeder reactor that is passively safe and could be remotely shut down in case the suspicion arises that it is being tampered with.
The Clean And Environmentally Safe Advanced Reactor (CAESAR) is a nuclear reactor concept that uses steam as a moderator - this design is still in development.
Subcritical reactors are designed to be safer and more stable, but pose a number of engineering and economic difficulties. One example is the Energy amplifier.
Thorium based reactors. It is possible to convert Thorium-232 into U-233 in reactors specially designed for the purpose. In this way, Thorium, which is more plentiful than uranium, can be used to breed U-233 nuclear fuel. U-233 is also believed to have favourable nuclear properties as compared to traditionally used U-235, including better neutron economy and lower production of long lived transuranic waste.
Advanced Heavy Water Reactor - A proposed heavy water moderated nuclear power reactor that will be the next generation design of the PHWR type. Under development in the Bhabha Atomic Research Centre (BARC).
KAMINI - A unique reactor using Uranium-233 isotope for fuel. Built by BARC and IGCAR Uses thorium.
India is also building a bigger scale FBTR or fast breeder thorium reactor to harness the power with the use of thorium.
Generation IV reactors
Generation IV reactors are a set of theoretical nuclear reactor designs currently being researched. These designs are generally not expected to be available for commercial construction before 2030. Current reactors in operation around the world are generally considered second- or third-generation systems, with the first-generation systems having been retired some time ago. Research into these reactor types was officially started by the Generation IV International Forum (GIF) based on eight technology goals. The primary goals being to improve nuclear safety, improve proliferation resistance, minimize waste and natural resource utilization, and to decrease the cost to build and run such plants.
Fueling of nuclear reactors:
The amount of energy in the reservoir of nuclear fuel is frequently expressed in terms of "full-power days," which is the number of 24-hour periods (days) a reactor is scheduled for operation at full power output for the generation of heat energy. The number of full-power days in a reactor's operating cycle (between refueling outage times) is related to the amount of fissile uranium-235 (U-235) contained in the fuel assemblies at the beginning of the cycle. A higher percentage of U-235 in the core at the beginning of a cycle will permit the reactor to be run for a greater number of full-power days.
At the end of the operating cycle, the fuel in some of the assemblies is "spent" and is discharged and replaced with new (fresh) fuel assemblies, although in practice it is the buildup of reaction poisons in nuclear fuel that determines the lifetime of nuclear fuel in a reactor. Long before all possible fission has taken place, the buildup of long-lived neutron absorbing fission byproducts impedes the chain reaction. The fraction of the reactor's fuel core replaced during refueling is typically one-fourth for a boiling-water reactor and one-third for a pressurized-water reactor.
Not all reactors need to be shut down for refueling; for example, pebble bed reactors, RBMK reactors, molten salt reactors, Magnox, AGR and CANDU reactors allow fuel to be shifted through the reactor while it is running. In a CANDU reactor, this also allows individual fuel elements to be situated within the reactor core that are best suited to the amount of U-235 in the fuel element.
The amount of energy extracted from nuclear fuel is called its "burn up," which is expressed in terms of the heat energy produced per initial unit of fuel weight. Burn up is commonly expressed as megawatt days thermal per metric ton of initial heavy metal.
 Failure modes of nuclear power plants
Diagram demonstrating the defense in depth quality of nuclear power plants.
1st layer of defense is the inert, ceramic quality of the uranium oxide itself.
2nd layer is the air tight zirconium alloy of the fuel rod.
3rd layer is the reactor pressure vessel made of steel more than a dozen centimeters thick.
4th layer is the pressure resistant, air tight containment building.
5th layer is the reactor building or in newer powerplants a second outer containment building.
There are concerns that a combination of human and mechanical error at a nuclear facility could result in significant harm to people and the environment:
Operating nuclear reactors contain large amounts of radioactive fission products which, if dispersed, can pose a direct radiation hazard, contaminate soil and vegetation, and be ingested by humans and animals. Human exposure at high enough levels can cause both short-term illness and death and longer-term death by cancer and other diseases.
Nuclear reactors can fail in a variety of ways. Should the instability of the nuclear material generate unexpected behavior, it may result in an uncontrolled power excursion. Normally, the cooling system in a reactor is designed to be able to handle the excess heat this causes; however, should the reactor also experience a loss-of-coolant accident, then the fuel may melt or cause the vessel it is contained in to overheat and melt. This event is called a nuclear meltdown.
Because the heat generated can be tremendous, immense pressure can build up in the reactor vessel, resulting in a steam explosion, which happened at Chernobyl. However, the reactor design used at Chernobyl was unique in many ways. It utilized a positive void coefficient, meaning a cooling failure caused reactor power to rapidly escalate. All reactors built outside the former Soviet Union have had negative void coefficients, a passively safe design. More importantly though, the Chernobyl plant lacked a containment structure. Western reactors have this structure, which acts to contain radiation in the event of a failure. Containment structures are some of the strongest structures built by mankind, and can withstand tornado-force winds or a direct strike from an aircraft carrier.
Intentional cause of such failures may be the result of nuclear terrorism.
Hazards of nuclear material
Nuclear material may be hazardous if not properly handled or disposed of. Experiments of near critical mass-sized pieces of nuclear material can pose a risk of a criticality accident. David Hahn, "The Radioactive Boy Scout" who tried to build a nuclear reactor at home, serves as an excellent example of a nuclear experimenter who failed to develop or follow proper safety protocols. Such failures raise the specter of radioactive contamination.
Even when properly contained, fission byproducts which are no longer useful generate radioactive waste, which must be properly disposed of. In addition, material exposed to neutron radiation-present in nuclear reactors-may become radioactive in its own right, or become contaminated with nuclear waste. Additionally, toxic or dangerous chemicals may be used as part of the plant's operation, which must be properly handled and disposed of.
Vulnerability of nuclear plants to attack
Nuclear power plants are generally (although not always) considered "hard" targets. In the U.S., plants are surrounded by a double row of tall fences which are electronically monitored. The plant grounds are patrolled by a sizeable force of armed guards. The NRC's "Design Basis Threat" criteria for plants is a secret, and so what size of attacking force the plants are able to protect against is unknown. However, to scram (make an emergency shutdown) a plant takes less than 5 seconds while unimpeded restart takes hours, severely hampering a terrorist force in a goal to release radioactivity.
Attack from the air is an issue that has been highlighted since the September 11 attacks in the U.S. However, it was in 1972 when three hijackers took control of a domestic passenger flight along the east coast of the U.S. and threatened to crash the plane into a U.S. nuclear weapons plant in Oak Ridge, Tennessee. The plane got as close as 8,000 feet above the site before the hijackers' demands were met.
The most important barrier against the release of radioactivity in the event of an aircraft strike on a nuclear power plant is the containment building and its missile shield. Current NRC Chairman Dale Klein has said "Nuclear power plants are inherently robust structures that our studies show provide adequate protection in a hypothetical attack by an airplane. The NRC has also taken actions that require nuclear power plant operators to be able to manage large fires or explosions-no matter what has caused them."
In addition, supporters point to large studies carried out by the U.S. Electric Power Research Institute that tested the robustness of both reactor and waste fuel storage and found that they should be able to sustain a terrorist attack comparable to the September 11 terrorist attacks in the U.S. Spent fuel is usually housed inside the plant's "protected zone"or a spent nuclear fuel shipping cask; stealing it for use in a "dirty bomb" is extremely difficult. Exposure to the intense radiation would almost certainly quickly incapacitate or kill anyone who attempts to do so.
In September 2010, analysis of the Stuxnet computer worm suggested that it was designed to sabotage a nuclear power plant. Such a cyber attack would bypass the physical safeguards in place and so the exploit demonstrates an important new vulnerability.
New nuclear technologies
The next nuclear plants to be built will likely be Generation III or III+ designs, and a few such are already in operation in Japan. Generation IV reactors would have even greater improvements in safety. These new designs are expected to be passively safe or nearly so, and perhaps even inherently safe (as in the PBMR designs).
Some improvements made (not all in all designs) are having three sets of emergency diesel generators and associated emergency core cooling systems rather than just one pair, having quench tanks (large coolant-filled tanks) above the core that open into it automatically, having a double containment (one containment building inside another), etc.
However, safety risks may be the greatest when nuclear systems are the newest, and operators have less experience with them. Nuclear engineer David Lochbaum explained that almost all serious nuclear accidents occurred with what was at the time the most recent technology. He argues that "the problem with new reactors and accidents is twofold: scenarios arise that are impossible to plan for in simulations; and humans make mistakes" As one director of a U.S. research laboratory put it, "fabrication, construction, operation, and maintenance of new reactors will face a steep learning curve: advanced technologies will have a heightened risk of accidents and mistakes. The technology may be proven, but people are not".
Safety culture and human errors
One relatively prevalent notion in discussions of nuclear safety is that of safety culture. The International Nuclear Safety Advisory Group, defines the term as "the personal dedication and accountability of all individuals engaged in any activity which has a bearing on the safety of nuclear power plants". The goal is "to design systems that use human capabilities in appropriate ways, that protect systems from human frailties, and that protect humans from hazards associated with the system".
At the same time, there is some evidence that operational practices are not easy to change. Operators almost never follow instructions and written procedures exactly, and "the violation of rules appears to be quite rational, given the actual workload and timing constraints under which the operators must do their job". Many attempts to improve nuclear safety culture "were compensated by people adapting to the change in an unpredicted way". For this reason, training simulators are used.
An assessment conducted by the Commissariat a` l'EÂ´ nergie Atomique (CEA) in France concluded that no amount of technical innovation can eliminate the risk of human-induced errors associated with the operation of nuclear power plants. Two types of mistakes were deemed most serious: errors committed during field operations, such as maintenance and testing, that can cause an accident; and human errors made during small accidents that cascade to complete failure.
Nuclear and radiation accidents
Serious nuclear and radiation accidents include the Chernobyl disaster, Mayak disaster, Soviet submarine K-431 accident, Soviet submarine K-19 accident, Chalk River accidents, Windscale fire, Three Mile Island accident, Costa Rica radiotherapy accident, Zaragoza radiotherapy accident, Goiania accident, Church Rock uranium mill spill and the SL-1
Nuclear power plants in India
Atomic Power Stations in India (view)
Â Active plants
Â Plants under construction
Nuclear power is the fourth-largest source of electricity in India after thermal, hydro and renewable sources of electricity. As of 2010, India has 19 nuclear power plants in operation generating 4,560 MW while 4 other are under construction and are expected to generate an additional 2,720 MW. India's nuclear power industry is undergoing rapid expansion with plans to increase nuclear power output to 63,000 MW by 2032. The country is involved in the development of nuclear fusion reactors through its participation in the ITER project and is a global leader in the development of thorium-based fast breeder reactors.
India's domestic uranium reserves are relatively small and the country is dependent on uranium imports to fuel its nuclear power industry. Since early 1990s, Russia has been a major supplier of nuclear fuel to India. Due to dwindling domestic uranium reserves, electricity generation from nuclear power in India declined by 12.83% from 2006 to 2008. Following a waiver from the Nuclear Suppliers Group in September 2008 which allowed it to commence international nuclear trade, India has signed bilateral deals on civilian nuclear energy technology cooperation with several other countries, including France, the United States, the United Kingdom, and Canada. India has also uranium supply agreements with Russia, Mongolia, Kazakhstan, Argentina and Namibia.
India now envisages to increase the contribution of nuclear power to overall electricity generation capacity from 4.2% to 9% within 25 years. In 2010, India's installed nuclear power generation capacity will increase to 6,000 MW. As of 2009, India stands 9th in the world in terms of number of operational nuclear power reactors and is constructing 9 more, including two EPRs being constructed by France's Areva. Indigenous atomic reactors include TAPS-3, and -4, both of which are 540 MW reactors. India's US$717 million fast breeder reactor project is expected to be operational by 2010.
Nuclear Power Growth in India
India, being a non-signatory of the Nuclear Non-Proliferation Treaty, has been subjected to a defacto nuclear embargo from members of the Nuclear Suppliers Group (NSG) cartel. This has prevented India from obtaining commercial nuclear fuel, nuclear power plant components and services from the international market, thereby forcing India to develop its own fuel, components and services for nuclear power generation. The NSG embargo has had both negative and positive consequences for India's Nuclear Industry. On one hand, the NSG regime has constrained India from freely importing nuclear fuel at the volume and cost levels it would like to support the country's goals of expanding its nuclear power generation capacity to at least 20,000 MW by 2020. Also, by precluding India from taking advantage of the economies of scale and safety innovations of the global nuclear industry, the NSG regime has driven up the capital and operating costs and damaged the achievable safety potential of Indian nuclear power plants. On the other hand, the NSG embargo has forced the Indian government and bureaucracy to support and actively fund the development of Indian nuclear technologies and industrial capacities in all key areas required to create and maintain a domestic nuclear industry. This has resulted in the creation of a large pool of nuclear scientists, engineers and technicians that have developed new and unique innovations in the areas of Fast Breeder Reactors, Thermal Breeder Reactors, the Thorium fuel cycle, nuclear fuel reprocessing and Tritium extraction & production. Ironically, had the NSG sanctions not been in place, it would have been far more cost effective for India to import foreign nuclear power plants and nuclear fuels than to fund the development of Indian nuclear power generation technology, building of India's own nuclear reactors, and the development of domestic uranium mining, milling and refining capacity.
The Indian nuclear power industry is expected to undergo a significant expansion in the coming years thanks in part to the passing of The Indo-US nuclear deal. This agreement will allow India to carry out trade of nuclear fuel and technologies with other countries and significantly enhance its power generation capacity. when the agreement goes through, India is expected to generate an additional 25,000 MW of nuclear power by 2020, bringing total estimated nuclear power generation to 45,000 MW.
India has already been using imported enriched uranium and are currently under International Atomic Energy Agency (IAEA) safeguards, but it has developed various aspects of the nuclear fuel cycle to support its reactors. Development of select technologies has been strongly affected by limited imports. Use of heavy water reactors has been particularly attractive for the nation because it allows Uranium to be burnt with little to no enrichment capabilities. India has also done a great amount of work in the development of a Thorium centered fuel cycle. While Uranium deposits in the nation are limited (see next paragraph) there are much greater reserves of Thorium and it could provide hundreds of times the energy with the same mass of fuel. The fact that Thorium can theoretically be utilized in heavy water reactors has tied the development of the two. A prototype reactor that would burn Uranium-Plutonium fuel while irradiating a Thorium blanket is under construction at the Madras/Kalpakkam Atomic Power Station.
Uranium used for the weapons program has been separate from the power program, using Uranium from indigenous reserves. This domestic reserve of 80,000 to 112,000 tons of uranium (approx 1% of global uranium reserves) is large enough to supply all of India's commercial and military reactors as well as supply all the needs of India's nuclear weapons arsenal. Currently, India's nuclear power reactors consume, at most, 478 metric tonnes of uranium per year. Even if India were quadruple its nuclear power output (and reactor base) to 20GW by 2020, nuclear power generation would only consume 2000 metric tonnes of uranium per annum. Based on India's known commercially viable reserves of 80,000 to 112,000 tons of uranium, this represents a 40 to 50 years uranium supply for India's nuclear power reactors (note with reprocessing and breeder reactor technology, this supply could be stretched out many times over). Furthermore, the uranium requirements of India's Nuclear Arsenal are only a fifteenth (1/15) of that required for power generation (approx. 32 tonnes), meaning that India's domestic fissile material supply is more than enough to meet all needs for it strategic nuclear arsenal. Therefore, India has sufficient uranium resources to meet its strategic and power requirements for the foreseeable future.
Nuclear power plants
Currently, nineteen nuclear power reactors produce 4,560.00 MW (2.9% of total installed base).
Total capacity (MW)
220 x 3
220 x 2
220 x 2
220 x 2
100 x 1
200 x 1
220 x 4
160 x 2
540 x 2
The projects under construction are:
Total capacity (MW)
220 x 1
1000 x 2
500 x 1
The planned projects are:
Total capacity (MW)
640 x 2
640 x 2
1200 x 2
1600 x 4
1000 x 1, 1500 x 1
470 x 4
1000 x 2
640 x 4
The following projects are firmly proposed.
Total capacity (MW)
1200 x 2
1600 x 2
NPCIL51%, AP Genco 49%
2000 x 1
The following projects are proposed and to be confirmed soon.
Total capacity (MW)
1200 x 2
Several nuclear accidents have occurred in India:
Nuclear power plant accidents in India
4 May 1987
Fast Breeder Test Reactor at Kalpakkam refuelling accident that ruptures the reactor core, resulting in a two-year shutdown
10 September 1989
Tarapur, Maharashtra, India
Operators at the Tarapur Atomic Power Stationfind that the reactor had been leaking radioactive iodine at more than 700 times normal levels. Repairs to the reactor take more than a year
13 May 1992
Tarapur, Maharashtra, India
A malfunctioning tube causes the Tarapur Atomic Power Station to release 12 curies of radioactivity
31 March 1993
Bulandshahr, Uttar Pradesh, India
The Narora Atomic Power Stationsuffers a fire at two of its steam turbine blades, damaging the heavy water reactor and almost leading to a meltdown
2 February 1995
Kota, Rajasthan, India
The Rajasthan Atomic Power Stationleaks radioactive helium and heavy water into the Rana Pratap Sagar River, necessitating a two-year shutdown for repairs
22 October 2002
Almost 100 kg radioactive sodium at a fast breeder reactor leaks into a purification cabin, ruining a number of valves and operating systems
It is estimated that before the accident at Tarapur, lack of proper maintenance exposed more than 3000 Indian personnel to "very high" and "hazardous" radiation levels. Researchers at the American University calculated at least 124 "hazardous incidents" at nuclear plants in India between 1993 and 1995.
Most nuclear reactors use a chain reaction to induce a controlled rate of nuclear fission in fissile material, releasing both energy and free neutrons. A reactor consists of an assembly of nuclear fuel (a reactor core), usually surrounded by a neutron moderator such as water, graphite, or zirconium hydride, and fitted with mechanisms such as control rods that control the rate of the reaction.
The physics of nuclear fission has several quirks that affect the design and behavior of nuclear reactors; this article presents a general overview of the physics of nuclear reactors and their behavior.
Uranium enrichment is extremely difficult, because the chemical properties of 235U and 238U are identical, so physical processes such as gas diffusion or mass HYPERLINK "http://en.wikipedia.org/wiki/Mass_spectrometer"spectrometry must be used to separate the isotopes based on their slightly different mass. Because enrichment is the main technical hurdle to production of nuclear fuel and simple nuclear weapons, enrichment technology is politically sensitive.