NUCLEAR ENERGY
Nuclear energy is a form of energy that is generated from the nucleus of an atom. It is released through two main processes: nuclear fission and nuclear fusion.
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Nuclear Fission: Nuclear fission is the process by which the nucleus of a heavy atom, such as uranium-235 or plutonium-239, is split into two or more smaller nuclei, along with the release of a significant amount of energy. This process can be controlled and sustained in a nuclear reactor. In a nuclear power plant, the heat produced by nuclear fission is used to generate steam, which, in turn, drives turbines connected to generators. These generators produce electricity, which is then distributed for various purposes.
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Nuclear Fusion: Nuclear fusion is the process of combining the nuclei of light atoms, such as isotopes of hydrogen (e.g., deuterium and tritium), to form a heavier nucleus, along with the release of energy. Fusion is the process that powers the sun and other stars. It has the potential to provide a nearly limitless and cleaner source of energy compared to fission. However, achieving controlled nuclear fusion on Earth has proven to be technologically challenging and has not yet been realized for widespread energy production.
Nuclear energy serves several important purposes and is considered valuable for various reasons, which include:
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Low Greenhouse Gas Emissions: Nuclear power plants produce electricity with very low greenhouse gas emissions. This makes nuclear energy an attractive option for countries aiming to reduce their carbon footprint and combat climate change. It provides a source of electricity that is relatively clean and doesn't release significant amounts of carbon dioxide or other greenhouse gases into the atmosphere.
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Reliable Baseload Power: Nuclear energy provides a consistent and reliable source of electricity, known as baseload power. Unlike some renewable energy sources, such as wind and solar, which are intermittent and weather-dependent, nuclear power can operate continuously and meet the minimum electricity demand, ensuring grid stability.
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Energy Security: Nuclear energy can contribute to energy security by diversifying a nation's energy sources. This reduces the reliance on fossil fuels, which can be subject to price volatility and supply disruptions due to geopolitical conflicts.
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High Energy Density: Nuclear fission, the process used in nuclear power plants, has a high energy density, meaning that a small amount of nuclear fuel can produce a large amount of energy. This is particularly important in scenarios where space and resource constraints are factors.
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Long Fuel Supply: Uranium, the primary fuel used in nuclear reactors, is relatively abundant and can provide a stable and long-term source of energy. Additionally, there is ongoing research into advanced nuclear technologies, such as breeder reactors, which can extend the use of nuclear fuel resources.
- Reduced Air Pollution: In addition to lower greenhouse gas emissions, nuclear power plants do not produce the air pollutants associated with fossil fuel combustion, such as sulfur dioxide, nitrogen oxides, and particulate matter, which can have adverse health effects and contribute to air pollution.
- High Energy Independence: Nations with nuclear power capabilities can reduce their dependence on imported fossil fuels. This enhances energy independence and can have economic and geopolitical benefits.
Water reactors are a common type of nuclear reactor that use water as a coolant and/or moderator. There are several types of water reactors, including pressurized water reactors (PWRs) and boiling water reactors (BWRs). Here's an overview of these two main types:
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Pressurized Water Reactors (PWRs):
- Pressurized Water Reactors (PWRs) are the most prevalent type of commercial nuclear reactors in the world.
- PWRs use ordinary water (light water) as both a coolant and a moderator. The water is kept at high pressure to prevent it from boiling.
- The reactor core contains fuel rods, typically enriched uranium, and control rods to regulate the nuclear reaction.
- The heat generated in the reactor core is transferred to a secondary loop of water (usually at lower pressure) through a heat exchanger. This secondary loop is used to produce steam to drive turbines and generate electricity.
- PWRs are known for their safety features, as the high pressure in the primary coolant loop helps prevent the release of radioactive materials.
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Boiling Water Reactors (BWRs):
- Boiling Water Reactors (BWRs) also use water as a coolant and moderator, but they allow the water in the reactor core to boil.
- The fuel rods are located in the reactor core, and as the nuclear fission reactions occur, they generate heat, causing the water in direct contact with the fuel rods to boil and produce steam.
- The steam from the reactor core is directly used to drive turbines and generate electricity without the need for a separate heat exchanger.
- BWRs are simpler in design but have different safety features compared to PWRs.
| Pressurized Heavy Water Reactor (PHWR) | Light Water Reactor (LWR) | Prototype Fast Breeder Reactor (FBR) | |
| Coolant and Moderator | Uses heavy water (deuterium oxide, D2O) as both the coolant and moderator. Heavy water moderates the neutrons and helps sustain the nuclear chain reaction | Uses ordinary light water (H2O) as both the coolant and moderator. The light water absorbs some neutrons, which affects the reactivity of the reactor | Uses a liquid metal coolant (sodium or lead) and typically does not use a separate moderator. The fast neutrons produced in the reactor core drive the breeding of fissile material. |
| Fuel | Typically uses natural uranium or slightly enriched uranium as fuel. It relies on heavy water to sustain the chain reaction | Uses enriched uranium (typically U-235) or mixed oxide (MOX) fuel, which contains both uranium and plutonium. Light water reactors require enriched fuel to compensate for neutron absorption by the coolant | Uses plutonium or enriched uranium as fuel. The reactor is designed to create more fissile material (usually plutonium-239) than it consumes |
| Neutron Spectrum | Has a thermal neutron spectrum, where neutrons have lower energy and are moderated by heavy water | Also has a thermal neutron spectrum, where neutrons are moderated by light water | Operates with a fast neutron spectrum, meaning that neutrons have higher energy and are not significantly moderated. This allows for efficient breeding of fissile material |
| Efficiency | Relatively low thermal efficiency due to the neutron-absorbing properties of heavy water | Moderate thermal efficiency. Most commercial nuclear power plants worldwide are LWRs | High potential for efficiency as it can produce more fissile material than it consumes, making it a potential source of sustainable nuclear fuel. |
| Development and Use | Used in some countries like Canada and India for power generation | The most common reactor type for commercial power generation worldwide | Developed as a prototype for future breeder reactor technology. Few operational FBRs exist |
The following are nuclear power plants in India:
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Tarapur Atomic Power Station (TAPS):
- Located in Tarapur, Maharashtra.
- Features two boiling water reactors (BWRs) and two pressurized heavy water reactors (PHWRs).
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Kakrapar Atomic Power Station (KAPS):
- Located in Kakrapar, Gujarat.
- Consists of two pressurized heavy water reactors (PHWRs).
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Rajasthan Atomic Power Station (RAPS):
- Located in Rawatbhata, Rajasthan.
- Comprises several units, including both pressurized heavy water reactors (PHWRs) and pressurized heavy water reactors with enriched uranium (PHWRs-PU).
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Madras Atomic Power Station (MAPS):
- Located in Kalpakkam, Tamil Nadu.
- Features two pressurized heavy water reactors (PHWRs) and a Prototype Fast Breeder Reactor (PFBR).
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Narora Atomic Power Station (NAPS):
- Located in Narora, Uttar Pradesh.
- Houses two pressurized heavy water reactors (PHWRs).
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Kaiga Generating Station (KGS):
- Located in Kaiga, Karnataka.
- Operates with pressurized heavy water reactors (PHWRs).
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Kudankulam Nuclear Power Plant:
- Located in Kudankulam, Tamil Nadu.
- Currently, it has two VVER-1000 pressurized water reactors (PWRs) in operation, and additional units were under construction.
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Gorakhpur Haryana Anu Vidyut Pariyojana (GHAVP):
- Located in Fatehabad, Haryana.
- Houses two pressurized heavy water reactors (PHWRs).
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