Table of Contents
Seminar On Nuclear Power Plant Report PDF Download
A nuclear power plant is a thermal power station in which the heat source is a nuclear reactor. As is typical in all conventional thermal power stations the heat is used to generate steam which drives a steam turbine connected to a electric generator which produces electricity. Nuclear power plants are usually considered to be base load stations, since fuel is a small part of the cost of production. Nuclear power plants are not located according to specific attributes of geography, and are therefore found all over the world. Although as a coin has two sides, nuclear power plants also have many merits and demerits. The present status of nuclear energy and future is also discussed further.
Conventional thermal power stations use oil or coal as the source as the source of energy. The reserves of these fuels are becoming depleted in many countries and thus there is a tendency to seek alternative sources of energy. In a nuclear power station instead of a furnace there is a nuclear reactor, in which heat is generated by splitting atoms of radioactive material under suitable conditions. The conversion to electrical energy takes place indirectly, as in conventional thermal power plants. The heat is produced by fission in a nuclear reactor. Directly or indirectly, water vapor (steam) is produced. The pressurized steam is then usually fed to a multi-stage steam turbine. For economical use in a power system a nuclear power station generally has to be large and where large units are justifiable.
Components of a Nuclear Power Plant
The Various Components of a Nuclear Power Plant are:
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. In its central part, the reactor core’s heat is generated by controlled nuclear fission. With this heat, a coolant is heated as it is pumped through the reactor and thereby removes the energy from the reactor. Heat from nuclear fission is used to raise steam, which runs through turbines, which in turn powers either ship’s propellers or electrical generators.
A cooling system removes heat from the reactor core and transports it to another area of the plant, where the thermal energy can be harnessed to produce electricity or to do other useful work. Typically the hot coolant is used as a heat source for a boiler, and the pressurized steam from that one or more steam turbine driven electrical generators. Almost all currently operating nuclear power plants are light water reactors using ordinary water under high pressure as coolant and neutron moderator.
In the event of an emergency, safety valves can be used to prevent pipes from bursting or the reactor from exploding. The valves are designed so that they can derive all of the supplied flow rates with little increase in pressure. In the case of the BWR, the steam is directed into the suppression chamber and condenses there. The chambers on a heat exchanger are connected to the intermediate cooling
The water level in the steam generator and nuclear reactor is controlled using the feedwater system. The feedwater pump has the task of taking the water from the condensate system, increasing the pressure and forcing it into either the steam generators (in the case of a pressurized water reactor) or directly into the reactor (for boiling water reactors).
The steam generated from the boiler is used to drive the turbine. This turbine is connected to an electric generator so as to generate electricity. Care is taken in maintaining the condition of the turbine as it handles steam of very high heat capacity. The turbines used in BWRs have to be radioactively sealed so as to avoid leakage of the radioactive water.
The generator converts kinetic energy supplied by the turbine into electrical energy. Low-pole AC synchronous generators of high rated power are used.
A cooling tower is a heat rejection device which extracts waste heat to the atmosphere through the cooling of a water stream to a lower temperature. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or, in the case of closed circuit dry cooling towers, rely solely on air to cool the working fluid to near the dry-bulb air temperature.
Emergency Power Supply:
Most nuclear plants require two distinct sources of offsite power feeding station service transformers that are sufficiently separated in the plant’s switchyard and can receive power from multiple transmission lines. Nuclear power plants are equipped with emergency power systems to maintain safety in the event of unit shutdown and loss of offsite power. Batteries provide uninterruptible power to instrumentation, control systems, and valves.. The emergency diesel generators do not power all plant systems, only those required to shut the reactor down safely, remove decay heat from the reactor, provide emergency core cooling, and, in some plants, spent fuel pool cooling.
Advantages of Nuclear Power Plant
- Space requirement of a nuclear power plant is less as compared to other conventional power plants of equal size.
- A nuclear power plant consumes very small quantity of fuel. Thus fuel transportation cost is less and large fuel storage facility is not needed.
- There is increased reliability of operation.
- Nuclear power plants are not affected by adverse weather conditions.
- Nuclear power plants are well suited to meet large power demands. They give better performance at higher load factors (80-90%).
- Materials expenditure on metal structures, piping, storage mechanisms are much lower for a nuclear power plant than a coal burning power plant.
- It does not require large quantity of water.
Disadvantages of Nuclear Power Plant
- Initial cost of nuclear power plant is higher as compared to hydro or steam power plant.
- Nuclear power plants are not well suited for varying load conditions.
- Radioactive wastes if not disposed carefully may have bad effect on the health of workers and other population.
- Maintenance cost of the plant is high.
- It requires highly trained personnel to handle nuclear power plants.
- Nuclear power plants generate external dependence. Not many countries have uranium mines and not all the countries have nuclear technology, so they have to hire both things overseas.
- Nuclear power plants are objectives of terrorist organizations
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