Nuclear Energy MCQ Quiz in मराठी - Objective Question with Answer for Nuclear Energy - मोफत PDF डाउनलोड करा

In the 60-year history of civil nuclear power generation, with over 18,500 cumulative reactor-years across 36 countries, there have been only three significant accidents at nuclear power plants:

1. Three Mile Island (USA 1979) where the reactor was severely damaged but radiation was contained and there were no adverse health or environmental consequences.
2. Chernobyl (Ukraine 1986) where the destruction of the reactor by steam explosion and fire killed two people initially plus a further 28 from radiation poisoning within three months, and had significant health and environmental consequences.
3. Fukushima Daiichi (Japan 2011) where three old reactors (together with a fourth) were written off after the effects of loss of cooling due to a huge tsunami were inadequately contained. There were no deaths or serious injuries due to radioactivity, though about 19,500 people were killed by the tsunami.

• In 1994 the Kakrapar nuclear power plant near the west coast of India was flooded due to heavy rains together with failure of weir control for an adjoining water pond, inundating turbine building basement equipment.
• The back-up diesel generators on site enabled core cooling using fire water, a backup to process water, since the offsite power supply failed.
• Following this, multiple flood barriers were provided at all entry points, inlet openings below design flood level were sealed and emergency operating procedures were updated.
• In December 2004 the Madras NPP and Kalpakkam PFBR site on the east coast of India was flooded by a tsunami surge from Sumatra.
• Construction of the Kalpakkam plant was just beginning, but the Madras plant shut down safely and maintained cooling.

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Beta Decay

• Nuclei that contain too many neutrons often undergo beta (β) decay, in which a neutron is converted to a proton and a high-energy electron that is ejected from the nucleus as a β particle.
• The general reaction for beta decay is therefore as follows:

• Although beta decay does not change the mass number of the nucleus, it results in an increase of +1 in the atomic number because of the addition of a proton in the daughter nucleus.
• Thus beta decay decreases the neutron-to-proton ratio, moving the nucleus toward the band of stable nuclei.

The Department of Atomic Energy (DAE) was established on August 3, 1954, by Presidential Order under the direct supervision of the Prime Minister. 

Key PointsStatement I: In India, the Department of Atomic Energy (D A E) is responsible as the nodal agency for nuclear emergencies in public domain.

• DAE has worked on nuclear power technology development as well as applications of radiation technologies in agriculture, medicine, industry, and basic research.
• Its function is to support research and development projects relevant to DAE's programs as well as worldwide collaboration in linked advanced scientific fields.
• The Department of Atomic Energy (DAE) has been designated as the country's nodal body for providing technical assistance to national and local authorities in the event of a nuclear or radiological emergency in the public sphere.

​Thus, Statement I is correct. 

Statement II: As a general practice, the DAE is responsible to ensure that elaborate and comprehensive safety systems are in place for the operation of any nuclear facility.

• The Atomic Energy Regulatory Board (AERB) under the DEA is responsible for reviewing, enforcing standards, and authorizing the siting, designing, construction, operation, and decommissioning of nuclear sites.
• The Department's mandate on which its programs are based includes increasing nuclear power's portion of the energy mix by deploying indigenous and other proven technologies.
• It is responsible for the construction and operation of research reactors for the manufacture of radioisotopes, as well as radiation technology applications in health, agriculture, industry, cancer care etc.

So, Statement II are correct.

Therefore, Both Statement I and Statement II are correct.

• Radiation can arise from human activities or from natural sources. Most radiation exposure is from natural sources.
• These include:
  • radioactivity in rocks and soil of the Earth's crust;
  • radon, a radioactive gas given out by many volcanic rocks and uranium ore;
  • cosmic radiation.
• The human environment has always been radioactive and accounts for up to 85% of the annual human radiation dose.
• Some of the ultraviolet (UV) radiation from the sun is considered ionizing radiation, and provides a starting point in considering its effects.
• Sunlight UV is important in producing vitamin D in humans, but too much exposure produces sunburn and, potentially, skin cancer.
• Skin tissue is damaged, and that damage to DNA may not be repaired properly, so that over time, cancer develops and may be fatal.
• Adaptation from repeated low exposure can decrease vulnerability. But exposure to sunlight is quite properly sought after in moderation, and not widely feared.
• A knowledge of the effects of shorter-wavelength ionizing radiation from atomic nuclei derives primarily from groups of people who have received high doses.
• The main difference from UV radiation is that beta, gamma and X-rays can penetrate the skin.

• In most reactors the fuel is ceramic uranium oxide (UO₂ with a melting point of 2800°C) and most is enriched.
• The fuel pellets (usually about 1 cm diameter and 1.5 cm long) are typically arranged in a long zirconium alloy (zircaloy) tube to form a fuel rod, the zirconium being hard, corrosion-resistant and transparent to neutrons.
• Numerous rods form a fuel assembly, which is an open lattice and can be lifted into and out of the reactor core.
• A significant industry initiative is to develop accident-tolerant fuels which are more resistant to melting under conditions such as those in the Fukushima accident, and with the cladding being more resistant to oxidation with hydrogen formation at very high temperatures under such conditions.
• Burnable poisons are often used in fuel or coolant to even out the performance of the reactor over time from fresh fuel being loaded to refuelling.
• These are neutron absorbers which decay under neutron exposure, compensating for the progressive build up of neutron absorbers in the fuel as it is burned, and hence allowing higher fuel burn-up.
• The best known is gadolinium, which is a vital ingredient of fuel in naval reactors where installing fresh fuel is very inconvenient, so reactors are designed to run more than a decade between refuellings.

As society advances, we are discovering more pollutants that are contributing to negative climate change effects and global warming. Many of these pollutants come from our manufacturing and power generating industries, and no matter how much they are minimized, there are always going to some pollutants that will enter our atmosphere. 

1) Fission based nuclear energy:

• Nuclear is a zero-emission clean energy source.
• It generates power through fission, which is the process of splitting uranium atoms to produce energy. The heat released by fission is used to create steam that spins a turbine to generate electricity without the harmful byproducts emitted by fossil fuels.
• According to the Nuclear Energy Institute (NEI), the United States avoided more than 476 million metric tons of carbon dioxide emissions in 2019. That’s the equivalent of removing 100 million cars from the road and more than all other clean energy sources combined.
• It also keeps the air clean by removing thousands of tons of harmful air pollutants each year that contribute to acid rain, smog, lung cancer, and cardiovascular disease.

2) Magneto-hydrodynamic: 

• Magnetohydrodynamics is the study of the magnetic properties and behavior of electrically conducting fluids.
• Examples of such magneto­fluids include plasmas, liquid metals, salt water, and electrolytes. 
• MHD power generation is a new system of electric power generation that is said to be of high efficiency and low pollution.
• As its name implies, Magneto Hydro Dynamics (MHD) concerned with the flow of a conducting fluid in the presence of the magnetic and electric fields.

3) Thermal Power:

• A thermal power station is a power station in which heat energy is converted to electric power.
• In most, a steam-driven turbine converts heat to mechanical power as an intermediate to electrical power. Water is heated, turns into steam, and drives a steam turbine which drives an electrical generator.
• Thermal power plants are known to pump out a lot of greenhouse gases and ash, which are by-products of burning fossil fuels. 

4) Photovoltaics (PV)

• It is the conversion of light into electricity using semiconducting materials. 
• A photovoltaic system employs solar modules, each comprising a number of solar cells, which generate electrical power. Solar energy systems/power plants do not produce air pollution, water pollution, or greenhouse gases. However, some toxic materials and chemicals are used to make the photovoltaic (PV) cells that convert sunlight into electricity.
• Some solar thermal systems use potentially hazardous fluids to transfer heat.

Thus, Fission based nuclear energy is the least polluting energy-generating technique.

Low And Intermediate Level Waste (LILW):

• Low and Intermediate Level Waste (LILW) radioactive waste are generated in radiation facilities and nuclear fuel cycle operations ranging from uranium processing, fuel fabrication, nuclear power plants, research reactors, radiochemical facilities and fuel reprocessing.
• LILW have generally high volumes and low levels of radioactivity.
• They are segregated based on their physical nature and different management techniques have been established based on their nature for their effective treatment.
• They are further classified based on their radioactivity as well as also based on half life of radionuclide, as short lived and long lived wastes.
• Significant quantum of LILW of diverse nature gets generated in different nuclear installations.
• They are essentially of two types:

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

Non-energy applications of nuclear technology include the production of radioisotopes and radiation for numerous important applications, some of the most common being:

Medicine and health:

• Medical uses of nuclear technology are widespread, ranging from diagnostic to therapeutic equipment, and including sterilization of equipment.
• Many researchers have studied isotopes of medical applications produced in the proton induced reaction on natural cadmium.

Food and agriculture:

• Nuclear technology is utilized for improving food preservation and increasing genetic variability.
• Such technology is also employed for enhancing the sustainability of agriculture, including such activities as improved fertilizer application management and insect control, as well as the conservation and management of existing water supplies and the identification of new ones.

Industry:

• Nuclear materials and techniques have been applied to a range of industrial needs.
• These include industrial and environmental tracers, instrumentation and radiography, as well as the detection and analysis of pollutants.

Research:

• Numerous research applications of nuclear energy exist, including the use of radioisotopes for determining the age of substances through dating.

Household:

• Radioisotopes are commonly used today in household smoke detectors.

Light water graphite-moderated reactor (LWGR)

• The main LWGR design is the RBMK, a Soviet design, developed from plutonium production reactors.
• It employs long (7 metre) vertical pressure tubes running through graphite moderator, and is cooled by water, which is allowed to boil in the core at 290°C and at about 6.9 MPa, much as in a BWR.
• Fuel is low-enriched uranium oxide made up into fuel assemblies 3.5 metres long.

Image source: World Nuclear Association

• With moderation largely due to the fixed graphite, excess boiling simply reduces the cooling and neutron absorption without inhibiting the fission reaction, and a positive feedback problem can arise, which is why they have never been built outside the Soviet Union.

Pressurised heavy water reactor (PHWR)

• The PHWR reactor has been developed since the 1950s in Canada as the CANDU, and from the 1980s in India.
• PHWRs generally use natural uranium (0.7% U-235) oxide as fuel, hence needs a more efficient moderator, in this case heavy water (D₂O).
• The PHWR produces more energy per kilogram of mined uranium than other designs, but also produces a much larger amount of used fuel per unit output.

Image source: ScienceDirect

• The moderator is in a large tank called a calandria, penetrated by several hundred horizontal pressure tubes which form channels for the fuel, cooled by a flow of heavy water under high pressure (about 100 times atmospheric pressure) in the primary cooling circuit, typically reaching 290°C.
• As in the PWR, the primary coolant generates steam in a secondary circuit to drive the turbines.
• The pressure tube design means that the reactor can be refuelled progressively without shutting down, by isolating individual pressure tubes from the cooling circuit.
• It is also less costly to build than designs with a large pressure vessel, but the tubes have not proved to be durable.

Advanced gas-cooled reactor (AGR)

• These are the second generation of British gas-cooled reactors, using graphite moderator and carbon dioxide as primary coolant.
• The fuel is uranium oxide pellets, enriched to 2.5 - 3.5%, in stainless steel tubes.
• The carbon dioxide circulates through the core, reaching 650°C and then past steam generator tubes outside it, but still inside the concrete and steel pressure vessel (hence 'integral' design).
• Control rods penetrate the moderator and a secondary shutdown system involves injecting nitrogen to the coolant.
• The high temperature gives it a high thermal efficiency – about 41%.
• Refuelling can be on-load.

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Fast neutron reactor (FNR)

• Some reactors do not have a moderator and utilise fast neutrons, generating power from plutonium while making more of it from the U-238 isotope in or around the fuel.
• While they get more than 60 times as much energy from the original uranium compared with normal reactors, they are expensive to build.
• Further development of them is likely in the next decade, and the main designs expected to be built in two decades are FNRs.
• If they are configured to produce more fissile material (plutonium) than they consume they are called fast breeder reactors (FBR).