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CHAPTER 7

Nuclear technology is “the technology that involves the reactions of atomic nuclei”.

Nuclear energy is produced naturally and in man-made operations under human control.

Naturally: some nuclear energy is produced naturally. For example, the Sun and other stars make heat and light by nuclear reactions.

Man-Made: Nuclear energy can be man-made too. Machines called nuclear reactors, nuclear power plants provide electricity for many cities. Man-made nuclear reactions also occur in the explosion of atomic bomb.

Types of Nuclear Reactions There are two types of nuclear reactions:

Nuclear fi ssion:

In nuclear fi ssion, the nuclei of atoms are split, causing energy to be released. The atom bomb and nuclear reactors work by fi ssion. Uranium nuclei can be easily split by shooting neutrons at them, thus resulting in release of energy.

Nuclear fusion:

In nuclear fusion, the nuclei of atoms are joined together, or fused. This happens only under very hot conditions. In the Sun, hydrogen nuclei fuse to make helium. The hydrogen bomb, humanity’s most powerful and destructive weapon, also works by fusion. The heat required to start the fusion reaction is so great that an atomic bomb is used to provide it. Hydrogen nuclei fuse to form helium and in the process release huge amounts of energy thus producing a huge explosion.

NUCLEARENERGY


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Where Does the Energy Come From?

When the uranium atom is split, some of the energy that held it together called binding energy is released as radiation in the form of heat. Therefore, the total mass does decrease a tiny bit during the reaction. Thus the energy released can be calculated by using the mass of fuel spent by using Einstein equation E=MC2.

Nuclear Power Reactor A nuclear reactor produces and controls the release of energy from splitting the atoms of certain elements. In a nuclear power reactor, the energy released is used as heat to make steam to generate electricity. In a research reactor, the main purpose is to utilise the actual neutrons produced in the core. In most naval reactors, steam drives a turbine directly for propulsion.The principles for using nuclear power to produce electricity are the same for different types of reactor. The energy released from continuous fi ssion of the atoms of the fuel is harnessed as heat in either a gas or water, and is used to produce steam. The steam is used to drive the turbines which produce electricity (as in fossil fuel power plants).There are several components common to all types of reactors:

Fuel: Usually pellets of uranium oxide (UO2) arranged in tubes to form fuel rods. The rods are arranged into fuel assemblies in the reactor core.Moderator: This is material which slows down the neutrons released from fi ssion so that they cause more fi ssion. It is usually water, but may be heavy water or graphite.Control rods: These are made with neutron-absorbing material such as cadmium, hafnium or boron, and are inserted or withdrawn from the core to control the rate of reaction, or to halt it. Secondary shutdown systems involve adding other neutron absorbers, usually as a fl uid, to the system.Coolant: A liquid or gas circulating through the core so as to transfer the heat from it. In light water reactors the moderator functions also as coolant.Pressure vessel or pressure tubes: Usually a robust steel vessel containing the reactor core and moderator/coolant, but it may be a series of tubes holding the fuel and conveying the coolant through the moderator.Steam generator: Part of the cooling system where the heat from the reactor is used to make steam for the turbine.Containment system: The structure around the reactor core which is designed to protect it from outside intrusion and to protect those outside from the effects of radiation in case of any malfunction inside. It is typically a metre-thick concrete and steel structure.

Main types of nuclear reactors Boiling Water Reactors: In a typical design concept of a commercial BWR, the following process occurs:

The core inside the reactor vessel creates heat.


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A steam-water mixture is produced when very pure water (reactor coolant) moves upward through the core, absorbing heat.The steam-water mixture leaves the top of the core and enters the two stages of moisture separation where water droplets are removed before the steam is allowed to enter the steamline.The steamline directs the steam to the main turbine, causing it to turn the turbine generator, which produces electricity.

The unused steam is exhausted to the condenser, where it is condensed into water. The resulting water is pumped out of the condenser with a series of pumps, reheated, and pumped back to the reactor vessel. The reactor’s core contains fuel assemblies that are cooled by water circulated using electrically powered pumps. These pumps and other operating systems in the plant receive their power from the electrical grid. If offsite power is lost, emergency cooling water is supplied by other pumps, which can be powered by onsite diesel generators. Other safety systems, such as the containment cooling system, also need electric power. BWRs contain between 370-800 fuel assemblies.

Pressurised Water Reactor: In a typical design concept of a commercial PWR, the following process occurs:

The core inside the reactor vessel creates heat. Pressurized water in the primary coolant loop carries the heat to the steam generator. Inside the steam generator, heat from the primary coolant loop vaporizes the water in a secondary loop, producing steam.The steamline directs the steam to the main turbine, causing it to turn the turbine generator, which produces electricity.

The unused steam is exhausted to the condenser, where it is condensed into water. The resulting water is pumped out of the condenser with a series of pumps, reheated, and pumped back to the steam generator. The reactor’s core contains fuel assemblies that are cooled by water circulated using electrically powered pumps. These pumps and other operating systems in the plant receive their power from the electrical grid. If offsite power is lost, emergency cooling water is supplied by other pumps, which can be powered by onsite diesel generators. Other safety systems, such as the containment cooling system, also need electric power. PWRs contain between 150-200 fuel assemblies.


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Fast Breeder Reactor: The nuclear chain reaction in the uranium fuel in a thermal reactor is sustained by slowing down the neutrons by a moderator. The chain reaction in Fast Breeder Test Reactor (FBTR) is sustained by fast neutrons. The number of neutrons released per fi ssion is more compared to that of thermal reactor. The extra neutrons are available for absorption in uranium-238 to transform it to fi ssile plutonium-239.In a thermal reactor typically only about 1-2 per cent of the natural uranium is utilized whereas in FBTRs, the utilization is increased 60 to 70 times.Considering the nuclear and heat transfer properties of various possible coolants, Sodium has been universally accepted as the coolant for FBTRs. In Thermal reactors water is used as a coolant.The radioactivity released to the atmosphere and the radiation dose received by the operating personnel in FBTRs has been much less compared to the water control reactors.FBTR is based on the design of the Rhapsodic reactor, France.The fuel used to FBTR is mixed carbide of plutonium and natural uranium. The carbide fuel has higher breeding ratio due to its higher density and thermal conductivity.Why India Prefers Fast Breeders:

A fast breeder reactor (FBR) breeds more fuel than it consumes that is it produces more plutonium than it consumes while generating power. For a uranium scarce country like India, it is an attractive technology. Plutonium produced in the thermal reactors as spent fuel is ideally suitable as the fuel material for use in the FBR due to its high fi ssion neutron yield.Since the number of neutrons produced in plutonium fi ssion is high, it helps to produce more plutonium from uranium (U238) used as a blanket surrounding the fuel core of the FBR.FBR also consumes less uranium and that too very effectively. While the thermal reactors exploit only 0.6 per cent uranium, a FBR utilizes 70-75 per cent of it. Thus, it leaves less radioactive waste to dispose of. In fact, many scientists in India prefer FBRs for the same reason.

N-Power Policy of India In the beginning of the Eighth Plan, it was aimed to produce 10,000 MW of power by 2000, to increase the nuclear power share in total power production. In order to achieve the above objective, the Central Government established Nuclear Power Corporation to coordinate various nuclear power organisations, in 1989.But, it was unlikely to achieve this objective, particularly after the disintegration of USSR, and then the target was reduced to 9000 MW. However, still it was not possible in the near future. Indian scientists have planned to achieve the above target in future through the development of three generations of nuclear reactors:


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First Generation Nuclear Reactors: These are the pressurized Heavy Water reactors with the capacity of 235 HW each and use natural uranium as fuel. Plutonium is the by-product.Second Generation Nuclear Reactors: These are planned to be the fast breeder reactors with the capacity of 500 HW each, and use Plutonium, a by-product of the fi rst generation reactors, as the fuel.Third Generation Nuclear Reactors: These are also planned to be the fast breeder reactors. This generation reactors will use fuel derived from second generation reactors and convert more Thorium into Uranium-233. So, the plan is to use vast Thorium deposits found in India.India has established fi rst generation nuclear reactors at Tarapur, Kalpakkam, Narora and Rawatbhata. Other two reactors of this grade are located at Kakrapar (Gujarat) and Kaiga (Karnataka). The fi rst generation reactors have reached commercial stage. The generation of power from nuclear energy began in India in 1969 with the commissioning of fi rst atomic power station at Tarapore (TAPS).The second generation reactor has commenced with the successful operation of the Fast Breeder Test Reactor (FBTR) named KAMINI (Kalpakkam Mini Reactor) in 1985 at the Indira Gandhi Centre for Atomic Research (IGCAR) at Kalpakkam in Tamil Nadu.The Kalpakkam reactor is the world’s fi rst fast-breeder reactor. The reactor has successfully used the mixed uranium - plutonium carbide fuel, hitherto untried elsewhere. Progress has also been made in the third generation reactor with the successful development of a U-233 based fuel. Work has commenced on the design of an Advanced Heavy Water Reactor which will make the use of thorium in power generation.

Advantages The amount of electricity produced in a nuclear power station is equivalent to that produced by a fossil fuelled power station.Nuclear power stations do not burn fossil fuels to produce electricity and consequently they do not produce damaging, polluting gases. Many supporters of nuclear power production say that this type of power is environmentally friendly and clean. In a world that faces global warming they suggest that increasing the use of nuclear power is the only way of protecting the environment and preventing catastrophic climate change.Many developed countries such as the USA and the UK no longer want to rely on oil and gas imported from the Middle East, a politically unstable part of the world.Countries such as France produce approximately 90 percent of their electricity from nuclear power and lead the world in nuclear power generating technology - proving that nuclear power is an economic alternative to fossil fuel power stations. Nuclear reactors can be manufactured small enough to power ships and submarines. If this was extended beyond military vessels, the number of oil burning vessels would be reduced and consequently pollution.

Disadvantages Nuclear power is a controversial method of producing electricity. Many people and environmental organisations are very concerned about the radioactive fuel it needs. There have been serious accidents with a small number of nuclear power stations. The accident at Chernobyl (Ukraine) in 1986, led to 30 people being killed and over 100,000 people being evacuated. In the preceding years another 200,00 people were resettled away from the radioactive area. Radiation was even detected over a thousand miles away in the UK as a result of the Chernobyl accident. It has been suggested that over time 2500 people died as a result of the accident. There are serious questions to be answered regarding the storage of radioactive waste produced through the use of nuclear power. Some of the waste remains radioactive (dangerous) for thousands of years and is currently stored in places such as deep caves and mines.Storing and monitoring the radioactive waste material for thousands of years has a high cost. Nuclear powered ships and submarines pose a danger to marine life and the environment. Old vessels can leak radiation if they are not maintained properly or if they are dismantled carelessly at the end of their working lives.


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Many people living near to nuclear power stations or waste storage depots are concerned about nuclear accidents and radioactive leaks. Some fear that living in these areas can damage their health, especially the health of young children.Many Governments fear that unstable countries that develop nuclear power may also develop nuclear weapons and even use them.

Non-energy Applications of Nuclear Energy Applications of Radioisotopes: When a combination of neutrons and protons, which does not already exist in nature, is produced artifi cially, the atom will be unstable and is called a radioactive isotope or radioisotope. There are also a number of unstable natural isotopes arising from the decay of primordial uranium and thorium. Overall around 1800 radioisotopes have been so far found. About 200 of these are used on a regular basis, and most-are produced artifi cially.Radioisotopes have very useful properties: radioactive emissions are easily detected and can be tracked until they disappear leaving no trace. Alpha, beta and gamma radiation, like X-rays, can penetrate seemingly solid objects, but are gradually absorbed by them. The extent of penetration depends upon several factors including the energy of the radiation, the mass of the particle and the density of the solid. These properties lead to many applications for radioisotopes in the scientifi c, medical, forensic and industrial fi elds.Naturally Occurring Radioisotopes and Their Applications

Chlorine-36: Used to measure sources of chloride and the age of water (up to 2 million years)Carbon-14: Used to measure the age of water (up to 50,000 years)Tritium (H-3): Used to measure ‘young’ groundwater (up to 30 years)Lead-210: Used to date layers of sand and soil up to 80 years

Artifi cially Produced Radioisotopes and their ApplicationsAmericium-241: Used in backscatter gauges, smoke detectors, fi ll height detectors and in measuring ash content of coal.Caesium-137: Used for radiotracer technique for identifi cation of sources of soil erosion and deposition, in density and fi ll height level switches.Cobalt-60: Used for gamma sterilization, industrial radiography, density and fi ll height switches.Gold-198 and Technetium-99: Used to study sewage and liquid waste movements, as well as tracing factory waste causing ocean pollution, and to trace sand movement in river beds and ocean fl oors.Strontium-90, Krypton-85, Thallium-204: Used for industrial gauging.Zinc-65 and Manganese-54: Used to predict the behavior of heavy metal components in effl uents from mining waste water.Iridium-192, Gold-198 and Chromium-57: Used to label sand to study coastal erosion.Ytterbium-169, Iridium-192 and Selenium-75: Used in gamma radiography and non-destructive testing.Tritiated Water: Used as a tracer to study sewage and liquid wastes.

Industrial Applications: Modern industry uses radioisotopes in a variety of ways to improve productivity and, in some cases, to gain information that cannot be obtained in any other way. The continuous analysis and rapid response of nuclear techniques, many involving, radioisotopes, mean that reliable fl ow and analytic data can be constantly available. This results in reduced costs with increased product quality.Sealed radioactive sources are used in industrial radiography, gauging applications and mineral analysis. Many process industries utilise fi xed gauges to monitor and control the fl ow of materials in pipes, distillation columns, etc, usually with gamma rays. This process is used in common industrial applications such as:

The automobile industry— to test steel quality in the manufacture of cars and to obtain the proper thickness of tin and aluminiumThe aircraft industry— to check for fl aws in jet enginesConstruction— to gauge the density of road surfaces and subsurfaces


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Pipeline companies— to test the strength of weldsOil, gas, and mining, companies— to map the contours of test wells and mine bores, andCable manufacturers— to check ski lift cables for cracks.

Short-lived radioactive material is used in fl ow tracing and mixing measurements. Gamma sterilisation is used for medical supplies, some bulk commodities and, increasingly, for food preservation.Gamma Sterilisation: Gamma irradiation is widely used for sterilizing medical products, for other products such as wool, and for food. Cobalt-60 is the main isotope used, since it is an energetic gamma emitter. It is produced in nuclear reactors, sometimes as a by-product of power generation.Large-scale irradiation facilities for gamma sterilization are used for disposable medical supplies such as syringes, gloves, clothing and instruments, many of which would be damaged by heat sterilization. Such facilities also process bulk products such as raw wool, archival documents and even wood, to kill parasites.Smaller gamma irradiators are used for treating blood for transfusions and for other medical applications. It is also used for food preservation. When food is irradiated it passes through a chamber where it is exposed to ionizing energy. This penetrates the food and destroys harmful organisms without cooking or otherwise altering its physical or chemical properties. For this reason, irradiation is currently the best available technology suitable for treating raw and partially raw food. It leaves no residue, does not change the taste, colour, or smell of the food, nor does it make food radioactive.Food irradiation:

greatly reduces or eliminates the number of disease causing bacteria and other harmful organisms;helps to keep meat, poultry and seafood fresh; also helps to maintain certain food and vegetable for longer periods and reduce food spoilage;can replace potentially harmful chemical fumigants when used to eliminate insects from dried grain, legumes, spices, dried fruit etc.; andhas the potential to be used for meeting quarantine requirements for international trade in fresh fruits and vegetables.

Nuclear Medicine: Nuclear medicine is defi ned as the branch of medicine that uses radioactive isotopes, nuclear radiation, electromagnetic variations of the components of the atomic nucleus and related biophysical techniques for the prevention, diagnosis, therapy and medical research.Clinical applications of radiopharmaceuticals cover virtually all medical specialties.Its scope includes the following:

Prevention: In this regard, the nuclear medicine applies the knowledge and skills that are proper hygiene, prophylactic and preventive medicine and radiation protection.Research: Nuclear medicine is developed in basic and applied research using radioactive isotopes and related biophysical techniques.Diagnosis: mainly includes the realization of functional, morphological, and analytical tests based on biochemical, physiological and pathophysiological principles, aimed at achieving a better knowledge and understanding of the structure and function of the human body in health or disease.Therapeutics: In addition to the important impact of diagnostic techniques of nuclear medicine for the treatment and management of patients, this specialty includes in its scope, some specifi c therapeutic indications made by the administration of radiopharmaceuticals to patients (therapy metabolic, endolymphatic, intracavitary, etc.). It also includes the treatment and prevention of biological effects from exposure to ionizing radiation, especially when exposure is due to external radiation or radioactive substances caused by pollution unsealed.

Agriculture: Nuclear techniques are used in farming and agricultural communities to combat disease and provide other benefi ts. The benefi ts are:

Combating pests and diseases: the sterile insect technique involves mass producing insect pests and sterilizing them with gamma radiation emitted by radioisotopes; when the males are released in the target region and mate with wild females of the pest population, they create no offspring. Gradually, the population is reduced.Increase crop production: exposing plants to small doses of radiation helps change the genetic make-up of plants and lead to improved varieties.


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Protecting land and resources: isotopes measure soil, water and nutrient storage, soil erosion, and fertilizer and pesticide waste; they enable farmers to keep closer track of their operations and use vital resources more sparingly and effectively.Ensuring food safety: irradiation is used in food to kill bacteria such as E.coli. Increasing livestock production : scientists use isotopes to study hormones and learn more about reproduction cycles, which helps in areas such as the timing of artifi cial-insemination programmes.

Mining and minerals Radioactive sources are used widely in the mining industry. For example, radioactive sources are used in non-destructive testing of pipeline blockages and welds; in measuring the density of material being drilled through; in testing the dynamic characteristics of blast furnaces, in the measurement of combustible volatile matter in coal, and for on-stream analysis of a wide range of minerals and fuels.Mining companies use radionuclides to locate and quantify mineral deposits, to map geological contours using test wells and mine bores, and to determine the presence of hydrocarbons.In milling and fl otation operations, instruments using radioactive sources are widespread. These devices have the advantage of providing reliable non-contact measurement. Examples include the measurement of density and moisture in ore or slurries (important for process control and achieving fi nal concentrate target moisture content). Other examples include measurement of levels in process tanks, slurry density and fl ows in piping, and levels in ore crushing chutes to detect blockages. Various sources are used in such devices, for example americium-241 and caesium-137. Density measurement is based on the absorption of gamma radiation as it passes through process material. Absorption is proportional to changes in material density, and as the measuring path is held constant, this indicates density.

Impact of Radiation There are many forms of radiation. Whether natural or man-made, radiation can be both harmful and benefi cial to the environment. The sun, for example can have positive and negative effects on plant and animal life. At low levels, radiation can be benefi cial to the environment. On the other hand ionized radiation such as x-rays, gamma rays, alpha and beta particles can be particularly harmful in excessive amounts.

Plant Growth: Natural radiation is often benefi cial to plant growth. It is necessary for many plants to receive some form of non-ionizing radiation. Radiation that produces light in order for photosynthesis to occur is a positive effect that radiation has on plant life. However, according to the Environmental Literacy Council, ionized radiation that occurs from nuclear material may result in weakening of seeds and frequent mutations. For instance, a nuclear plant, called Chernobyl in Russia leaked in 1986 that caused excessive amounts of radiation pollution in that region. A huge cloud of radiation was formed which resulted in a massive amount of destroyed plant life; particularly pine trees in that area. High doses of radiation can be devastating to the environment.Animal and Humans: The effect of radiation in the environment can be dangerous and fatal to humans and animals. The damage it causes depends on the level of radiation and the resiliency of the organism. Radiation causes molecules to lose electrons thus destroying it. Killing certain enzymes in the body can simply make you sick. However, once radiation damages DNA the body may not be able to repair itself. This can increase the chances of both animals and humans developing cancer. According to the US Department of Energy, after two nuclear explosions in Hiroshima and Nagasaki, survivors experience higher cases of cancer and child deformities. The nuclear explosions are examples of high levels of radiation. However, low doses of radiation can kill germs and decrease the number of food poisoning cases.Marine Life: The effects that radiation has on marine life can be dangerous. High levels of UV or ultraviolet radiation can cause a reduction in reproduction capabilities. It can also disrupt the timing that plants fl ower, which can result in changes in pollination patterns. According to NASA, it can also reduce the amount of food and oxygen that plankton produces. Plankton can respond to excessive amount of UV-B or Ultraviolet-B light by sinking deeper into the water. This decreases the amount


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of visible light required for photosynthesis, which reduces growth and reproduction. An increased amount of UV-B can also increase the amount of ozone produced at the lower atmosphere. While some plants can use this extra layer as a protective shield, other plants are highly sensitive to photochemical smog.

Issue of Radioactive Waste Radioactive wastes are generated during various operations of the nuclear fuel cycle. Mining, nuclear power generation, and various processes in industry, defense, medicine and scientifi c research produce byproducts that include radioactive wastes.Radioactive waste can be in gas, liquid or solid form, and its level of radioactivity can vary. The waste can remain radioactive for a few hours or several months or even hundreds of thousands of years. Depending on the level and nature of radioactivity, radioactive wastes can be classifi ed as exempt waste, Low & Intermediate level waste and High Level Waste

Low and Intermediate level (LIL): Liquid wastes have generally high volumes and low levels of radioactivity. They are further classifi ed as short lived and long lived wastes.Low level nuclear waste usually includes material used to handle the highly radioactive parts of nuclear reactors (i.e. cooling water pipes and radiation suits) and waste from medical procedures involving radioactive treatments or x-rays.Solid waste: Signifi cant quantum of solid LIL wastes of diverse nature gets generated in different nuclear installations. They are essentially of two types:

Primary wastes - comprising of radioactively contaminated equipment (metallic hardware) spent radiation sources etc.Secondary wastes - resulting from different operational activities, protective rubber and plastic wears, cellulosic and fi brous material, organic ion exchange resins fi lter cartridges and others.

Gaseous waste: The air in the working area and the environment is free from radioactive contamination. The off gas ventilation system in nuclear power plants play an important role in ensuring clean air.High Level Waste: High level radioactive liquid waste (HLW) containing most (~99%) of the radioactivity in the entire fuel cycle is produced during reprocessing of spent fuel.Issue of the long lived radioactive waste has been the focal point of debate for the success of nuclear power. Planning for management of HL waste thus takes into account the need for their effective isolation from the biosphere and their continuous surveillance for extended periods of time spanning several generations. To meet this objective in the long term, waste isolation systems comprising multiple barriers are employed so as to prevent the movement of radionuclides back to the human environment.

Management of radiation wastes In consideration to the primary objective of protecting human health, environment and future generations, the overall philosophy for safe management of radioactive wastes in India, is based on the concept of

Delay and Delay Dilute and Disperse Concentrate and Contain.

Effective management involves segregation, characterization, handling, treatment, conditioning and monitoring prior to fi nal disposal.Proper disposal is essential to ensure protection of the health and safety of the public and quality of the environment including air, soil, and water supplies.Radiological hazards associated with short lived wastes <30 years half life get signifi cantly reduced over a few hundred years by radioactive decay. The high level wastes contain large concentration of both short and long lived radionuclide’s, warranting high degree of isolation from the biosphere and usually calls for fi nal disposal into geological formation (repository)A key idea was that long-term disposal would be best carried out by identifying suitable sites at which the waste could be buried, a process called deep geological disposal


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Low level waste is comparatively easy to dispose of. The level of radioactivity and the half life of the radioactive isotopes in low level waste are relatively small. Storing the waste for a period of 10 to 50 years will allow most of the radioactive isotopes in low level waste to decay, at which point the waste can be disposed of as normal refuse.In Solid waste substantial amount of LIL wastes of diverse nature, gets generated in different nuclear installations. Treatment and conditioning of solid wastes are practiced, to reduce the waste volume in ways, compatible to minimizing the mobility of the contained radioactive materials. A wide range of treatment and conditioning processes are available today with mature industrial operations involving several interrelated steps and diverse technologies. A brief summary of the various radioactive waste management practices followed in India has been presented below:

Management of High-level radioactive wastes This concerns management and disposal of highly radioactive materials created during production of nuclear power. High level radioactive waste is generally material from the core of the nuclear reactor or nuclear weapon. The waste includes uranium, plutonium, and other highly radioactive elements made during fi ssion. Most of the radioactive isotopes in high level waste emit large amounts of radiation and have extremely long half-lives (some longer than 100,000 years) creating long time periods before the waste will settle to safe levels of radioactivity. The management of high level waste in the Indian context encompasses the following three stages:

Immobilization of high level liquid waste into vitrifi ed borosilicate glasses.Engineered interim storage of vitrifi ed waste for passive cooling and surveillance over a period of time qualifying it for ultimate disposal.Ultimate storage disposal of vitrifi ed waste a deep geological depository.

The basic requirement for geological formation to be suitable for the location of the radioactive waste disposal facility is remoteness from environment, absence of circulating ground water and ability to contain radionuclides for geologically long periods of time.

Initiatives in India At present, the nuclear waste produced by power plants are stored in underground facilities, the minister said, and no new ones will be required till 2075.“The areas, where the disposal structures are located, are kept under constant surveillance with the help of bore-wells laid out in a planned manner. The underground soil and water samples from these bore wells are routinely monitored and to confi rm effective confi nement of radioactivity present in the disposed waste.”Much of the ‘waste’ produced by current plants is intended to be mixed with Thorium after 30-40 years to be used as fuel.India is one of the few countries to have mastered the technology of vitrifi cation. Over the years BARC has developed the technology for vitrifi cation of HLW. India has a unique distinction of having operating vitrifi cation plant at Tarapur and Trombay. In our existing plant at Trombay vitrifi cation process is essentially batch operation consisting of heating and fusing of pre-concentrated waste and glass forming additives and is carried out in melters based on induction heating.Radioactive waste disposal practices have changed substantially over the last twenty years. Evolving environmental protection considerations have provided the impetus to improve disposal technologies, and, in some cases, clean up facilities that are no longer in use. Designs for new disposal facilities and disposal methods must meet environmental protection and pollution prevention standards that are stricter than were foreseen at the beginning of the atomic age.Disposal of radioactive waste is a complex issue, not only because of the nature of the waste, but also because of the stringent regulatory structure for dealing with radioactive waste. India has achieved self-reliance in the management of all type of radioactive waste. Decades of safe and successful operation of our waste management facility stand testimony to international standards. An ongoing effort to upgrade technology to minimize radioactive discharge is also on.

Institutions involved in Nuclear Energy Development AEC: India’s Atomic Energy Commission (AEC) was established in August 1948 within the Department of Scientifi c Research, which was set up in June 1948. The Department of Atomic Energy (DAE) came into existence in August 1954 through a Presidential Order. Thereafter, a Government Resolution in1958 transferred the DAE within the AEC. The Secretary to the Government of India in the DAE is the ex-offi cio Chairman of the AEC. The other Members of the AEC are appointed on the recommendation of the Chairman of the AEC


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DAE’s own Research & Development wings include: Bhabha Atomic Research Centre (BARC), Trombay: Trombay near Mumbai. A series of ‘research’ reactors and critical facilities was built here. Reprocessing of used fuel was fi rst undertaken at Trombay in 1964.BARC is also responsible for the transition to thorium-based systems. BARC is responsible for India’s uranium enrichment projects, the pilot Rare Materials Plant (RMP) at Ratnahalli near MysoreIndira Gandhi Centre for Atomic Research (IGCAR): IGCAR at Kalpakkam was set up in 1971. Two civil research reactors here are preparing for stage two of the thorium cycle. BHAVINI is located here and draws upon the centre’s expertise and that of NPCIL in establishing the fast reactor program, including the Fast Reactor Fuel Cycle Facility.The Raja Ramanna Centre for Advanced Technology (RRCAT): Multi-purpose research reactor (MPRR) for radioisotope production, testing nuclear fuel and reactor materials, and basic research.Atomic Minerals Directorate : The DAE’s Atomic Minerals Directorate for Exploration and Research (AMD) is focused on mineral exploration for uranium and thorium. It was set up in 1949, and is based in Hyderabad, with over 2700 staff. Variable Energy Cyclotron Centre: Variable Energy Cyclotron Centre is a premier R & D unit of the Department of Atomic Energy. This Centre is dedicated to carry out frontier research and development in the fi elds of Accelerator Science & Technology, Nuclear Science (Theoretical and Experimental), Material Science, Computer Science & Technology and in other relevant areas.Global Centre for Nuclear Energy Partnership : It will be the DAE’s sixth R&D facility. It is being built near Bahadurgarh in Haryana state and designed to strengthen India’s collaboration internationally. It will house fi ve schools to conduct research into advanced nuclear energy systems, nuclear security, radiological safety, as well as applications for radioisotopes and radiation technologies. Russia is to help set up four of the GCNEP schools.

Besides carrying out research at its own research centres, the DAE provides full support to seven aided institutions

Tata Institute of Fundamental Research(TIFR): The Tata Institute of Fundamental Research is a National Centre of the Government of India, under the umbrella of the Department of Atomic Energy, as well as a deemed University awarding degrees for master’s and doctoral programs. At TIFR, carry out basic research in physics, chemistry, biology, mathematics, computer science and science education. Main campus is located in Mumbai, but additional campuses are in Pune, Bangalore and Hyderabad.Tata Memorial Centre: The Tata Memorial Centre commissioned state of the art new operation theatres. For delivering hi-tech patient care, sophisticated facilities such as stereotactic radiosurgery and steriotactic and intensity modulated radiotherapy, were added.Saha Institute of Nuclear Physics: The Saha Institute of Nuclear Physics is an institution of basic research and training in physical and biophysical sciences located in Bidhannagar, Kolkata, India. The institute is named after the famous Indian physicist Meghnad Saha.Institute of Physics: Institute of Physics, Bhubaneswar is an autonomous research institution of the (DAE), Government of India.Institute for Plasma Research: Research and development in fusion technology continued at the Institute for Plasma ResearchHarish Chandra Research Institute: The Harish-Chandra Research Institute is an institution dedicated to research in Mathematics and Theoretical Physics, located in Allahabad, Uttar Pradesh in IndiaInstitute of Mathematical Sciences: The Institute of Mathematical Sciences (IMSc), founded in 1962 and based in the verdant surroundings of the CIT campus in Chennai, is a national institution which promotes fundamental research in frontier disciplines of the mathematical and physical sciences

AERB: The AERB reviews the safety and security of the country’s Operating Nuclear Power Plants, Nuclear Power Projects, Fuel Cycle Facilities, and Other Nuclear/Radiation Facilities and Radiation Facilities. The regulatory authority of AERB is derived from the rules and notifi cations promulgated under the Atomic Energy Act, 1962 and the Environmental (Protection) Act, 1986. The headquarters is in Mumbai. The mission of the Board is to ensure that the use of Ionising Radiation and Nuclear Power in India does not cause undue risk to health and the Environment. Currently, the Board consists of a full-time Chairman, an ex offi cio Member, three part-time Members and a Secretary.NPCIL : Nuclear Power Corporation of India Limited (NPCIL) is a Public Sector Enterprise under the administrative control of the Department of Atomic Energy (DAE),Government of India. The Nuclear


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Power Corporation of India Ltd (NPCIL) is responsible for design, construction, commissioning and operation of thermal nuclear power plants.NPCIL is presently (June-2016) operating 21 nuclear power reactors with an installed capacity of 5780 MW. The reactor fl eet comprises two Boiling Water Reactors (BWRs) and 18 Pressurised Heavy Water Reactors (PHWRs) including one 100 MW PHWR at Rajasthan which is owned by DAE, Government of India.

The AERB is a regulatory body, which derives administrative and fi nancial support from the Department of Atomic Energy. It reports to the secreatry, DAE.The DAE is also involved in the promotion of nuclear energy, and is also responsible for the functioning of the Nuclear Power Corporation of India Limited, which operates most nuclear power plants in the country.The DAE is thus responsible both for nuclear safety (through the AERB), as well as the operation of nuclear power plants (through NPCIL). This could be seen as a confl ict of interest.

Safety Standards in Nuclear Power Plants The performance of Indian nuclear power reactors in respect of safety has been excellent, with about 340 reactor years of safe, reliable and accident-free operation. The releases of radioactivity to the environment have been a small fraction of the limits prescribed by the Atomic Energy Regulatory Board (AERB). The yearly radiation dose around the Indian NPPs, measured over the last many years, is an insignifi cantly small fraction of natural radiation dose and the stipulated regulatory limits.At all nuclear power stations, state of the art safety measures are provided based on principles of redundancy (more numbers than required) and diversity (operating on different principles). These include fail safe shutdown system to safely shutdown the reactor, combination of active and passive (systems working on natural phenomena and not needing motive power or operator action) cooling systems to remove the heat from the core at all times and a robust containment to prevent release of radioactivity in all situations. In addition, all nuclear power plants are designed to withstand extreme natural events like earthquake, fl ooding, tsunami etc. A multi-tier safety mechanism comprising of safety review committees within Nuclear Power Corporation of India Limited (NPCIL) and safety review committees in the regulatory authority (Atomic Energy Regulatory Board- AERB) is in place to monitor the safety of nuclear power plants. In addition, a framework of periodic safety reviews, audits and inspection is in place.Nuclear power stations in coastal areas are designed taking into account the technical parameters related to earthquake, tsunami, storm surges, fl oods etc. at each site. Appropriate bunds are provided at Tarapur, Kalpakkam and Kudankulam sites for shore protection. The shore protection measures are designed and constructed to withstand the possible impact of natural events. Surveillance of these protection measures is carried out periodically. Post Fukushima, the safety review of all nuclear power plants was conducted by task forces of NPCIL and the expert committee of AERB. These safety reviews have found that Indian nuclear power plants are safe and have margins and features in design to withstand extreme events like earthquakes and tsunamis.

CAG Report related to Safety of Nuclear plants Controller and Auditor General (CAG) has pointed out some issues, which needs serious consideration:

Legal status of AERB: The sole regulatory agency AERB, still acts as an arm of government, without much authority to frame and revise rules related to nuclear safety.Inadequate emergency preparedness: Most of the power plant lack state of art technology & protocols to deal with emergency situations.Location & site clearance: Persistent land acquisition and environmental clearance issues and lack of proper planning of the nuclear unit may impair the ability to respond to exigencies. E.g. approach road to Tarapur atomic power station is highly congested.Other issues like uncertainty over compensation clause in nuclear liability act, has raised great concern given the poor record of India to give compensation to affected in case of industrial disasters (eg. Bhopal gas tragedy).


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What can be done? CAG highlighted the urgency to bolster AERB’s regulatory capacity by giving it a statutory backing and making it complete independent to frame and implement safety rules.Incorporate state of art safety infrastructure in power plants under construction. No compromise is selecting the most geologically stable location and other safety requirement Minimizing human handling of process in power plants and replacing them with smart robots & UAV.Promoting power plants to reuse nuclear waste to minimize waste generation. Greater awareness building among local community & district administration. About the risks, benefi ts and safety infrastructure at place.

Nuclear & Radiological Disasters Any radiation incident resulting in or having a potential to result in exposure to and/or contamination of the workers or the public in excess of the respective permissible limits can be termed is a nuclear/ radiological emergency. These emergencies can be broadly classifi ed in the following manner:

An accident-taking place in any nuclear facility of the nuclear fuel cycle.A ‘criticality’ accident in a nuclear fuel cycle facility where an uncontrolled nuclear chain reaction takes-place.An accident during the transportation of radioactive material.A large-scale nuclear disaster resulting from a nuclear weapon attack (as had happened at Hiroshima and Nagasaki in Japan),

The International Atomic Energy Agency ( IAEA) classifi es the above emergency scenarios under- two broad categories nuclear and radiological:

A nuclear emergency refers to an emergency situation in which there is, or is presumed to be, a hazard due to the release of energy along with radiation from a nuclear chain reaction.All other emergency situations, which have the potential hazard of radiation exposure due to decay of radioisotopes are classifi ed as radiological emergencies.

EFFECTS OF NUCLEAR WEAPONS

The effects is of nuclear weapons are analysed according to blast, heat, radiation and effects on climate and ecology. Blast Effects: It is the case with explosions caused by conventional weapons, most of the damage to ‘buildings and other structures from a nuclear explosion results, directly or indirectly, from the effects of blast. The very rapid expansion of the bomb materials produces a high-pressure pulse, or shock wave, that moves rapidly outward from the exploding bomb.Thermal Effects: The very high temperatures attained in a nuclear explosion result in the formation of a fi reball-man extremely hot incandescent mass of gas. The thermal radiation falling on exposed skin will cause fl ash burns. The heat radiation can start fi res in dry, fl ammable materials such as paper and some fabrics; these fi res spread in typically urban conditions. A nuclear explosion also produces a very powerful surge of elect magnetic capable of overloading power supply systems and burning out transistors .and capacitors.Climatic Effects: Besides the widespread blast, radiation, and fi re damage from individual bombs, a large-scale nuclear exchange between nations could conceivably have a catastrophic global effect on climate. It would throw enormous quantities of dust and smoke into the atmosphere, suffi cient to block out sunlight for several months, particularly in the Northern hemisphere. This would destroy plant life and create a sub-freezing climate until the dust dispersed. The ozone layer would also be affected, permitting further damage as a result of the Sun’s ultraviolet radiation.


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Institutional mechanism for it The Government of India has identifi ed Department of Atomic Energy (DAE) as the nodal agency for providing the necessary technical inputs to the national or local. The Ministry of Home Affairs (MHA) is the nodal ministry in such emergencies. For this purpose, a Crisis Management Group (CMG) has been functioning since 1987 at DAE.

Crisis Management Group (CMG) : It is immediately activated and it coordinates with the local authority in the -affected area. All the concerning authorities at the centre (NCMC/ NEC/NDMA)- to ensure that the necessary technical- inputs are available to respond to the nuclear/radiological’ emergency.Medical preparedness for nuclear emergencies : In each constituent unit of DAE, a few doctors have been dedicated and given the necessary training in the medical management of radiation emergencies. All nuclear power plants and the Bhabha Atomic Research Centre (BARC) are equipped with radiation monitoring instruments, have personnel decontamination centres and the necessary stock of antidote medicines and specifi c de-corporation agents for typical radioisotopes. Public awareness : To educate the people about the benefi cial aspects of nuclear radiation and to remove their misgivings about it, the authorities of nuclear fuel cycle facilities in general, and that of nuclear power stations in particular, are actively involved in carrying out regular public awareness programmes for people living in the vicinity of these facilities. Mitigation and preparation: Goals are to reduce radiation-induced health effects by preventing and to limit the occurrence of stochastic effects in the population. Domain of Action: The response actions within the site boundary of the nuclear facility -are the responsibility of the management of the nuclear facility whereas the implementation of the emergency response plans in the public domain (beyond the site boundary) is the responsibility of the concerned district authority. In the event of an off-site emergency having the potential for trans-boundary effects, necessary action is taken by DAE in accordance with the country’s international obligations.Specialized Response Teams: Four battalions of National Disaster Response Force (NDRF) are being specially trained by NDMA with assistance from DAE/DRDO to provide specialized response during a nuclear/radiological emergency/disaster. Role of Civil Defense : Selected civil defence personnel will be trained extensively in the subjects of radiation, radioactivity, radiation—protection, use of monitoring instruments, shielding, decontamination, waste disposal, etc. Role of Armed Forces : The armed forces will also gear up their nuclear disaster preparedness so that they can be inducted in the event of nuclear disasters.Periodic Exercises and Mock Drills: It focuses on roles and responsibilities resource identifi cation, use of equipment, understanding the effects of radiation on human beings, animals and the environment.Emergency Response Centres (ERCs) : ERCs will be set up at all levels (i.e., state .capitals and major cities) with the necessary manpower, instruments and equipment. Depending upon the location and assigned functions, these ERCs will also be maintained in a ready state to quickly respond to any nuclear/ radiological emergency. Radiation Detection, Monitoring Instruments and Protective Gear : The fi rst need is the availability of instruments for detecting and monitoring the radiation. An inventory of radiation monitoring instruments and protective gear will be built up by all the SDMAs and DDMAs in consultation with DAE.Real Time Monitoring Systems: A network of simple environmental monitors, the Indian Environmental Radiation Monitoring Network (IERMON) has been established by BARC. These monitors work on a 24 x 7 basis.

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SCIENCE & TECHNOLOGY · Nuclear Power Reactor A nuclear reactor produces and controls the release...

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Transcript of SCIENCE & TECHNOLOGY · Nuclear Power Reactor A nuclear reactor produces and controls the release...