Layout of Nuclear Power Plant:
The layout of nuclear power plant is shown in Fig.3.4.
The main components of nuclear power plant are 1. Nuclear reactor, 2. Steam generator, 3. Turbine, 4. Coolant pump & feed pump, and 5. Generator.
1. Nuclear reactor:
It consists of the following components.
(a) Core: This contains the nuclear fuel and space for coolant. The fuels used are U233, U235, Pu239
To have uniform release of heat, the fuel is shaped and located in the core.
(b) Moderator: The moderator is used to reduce the speed of the fast moving neutrons. For natural uranium, the following are used as moderators-graphite, heavy water or beryllium. For enriched uranium, the ordinary water is used as moderator.
(c) Control rods: The control rods are used to start the chain reaction, maintain the chain reaction at required level and to shut down during emergency. The control rods are made of cadmium, boron and hafnium.
(d) Coolant: Coolant is used to transfer the heat which is produced in the reactor to steam generator for rising the steam. The generally used coolants are ordinary & heavy water, air, carbon dioxide, helium and hydrogen and liquid metals like sodium and potassium.
(e) Reflector: Reflector is used to reflect the escaping neutrons back into the core. This improves the neutron economy of the reactor. The generally used reflectors are heavy water, graphite and beryllium.
(f) Radiation shield: Radiation shield is a concrete shield to absorb dangerous radiations like alpha, beta, gamma rays tend to escape to the atmosphere.
(g) Reactor vessel: This is a housing for all the equipment’s and it is designed in such a way that it can withstand high pressures safely. The reactor is positioned at the bottom of the vessel.
2. Steam generator:
In this, the steam is generated from the feed water by absorbing heat from the hot coolant from the reactor.
The generated steam is made to expand in the turbine to produce work. This work is converted into electricity by generator which is coupled with turbines.
4. Coolant pump & Feed pump:
The coolant pump is used to maintain the flow of coolant and the feed pump is to pump the feed water to the steam generator.
The generator is used to convert the mechanical energy into electrical energy. The generator is directly coupled to the turbine.