World Nuclear Association states that 16% of the world’s electricity is supplied by nuclear power, through 440 nuclear reactors in 31 countries. Nuclear power is one of the main sources of the world’s energy needs in the future since it is an emission-free alternative. A nuclear power plant is steam powered and fueled by a radioactive element such as uranium-235. In some cases, plutonium-239 is also used as a nuclear fuel. There are different types of reactors used in a nuclear power plant such as Pressurized Water Reactor (PWR), Boiling Water Reactor (BWR), Pressurized Heavy Water Reactor (PHWR), Advanced Gas-cooled Reactor (AGR), etc. Read through the following lines to know the working of a nuclear power plant.
Working Of A Nuclear Power Plant
In a nuclear power plant, the uranium atoms are split in the process of nuclear fission, which in turn produces large amounts of energy. This energy is then, converted to heat. The heat thus created boils the water to produce steam, which in turn, rotates the turbines. The turbines then spin the shaft of the generator, which then spins the coils of the wire in the generator in a magnetic field, to produce electricity. A nuclear reactor is placed within a nuclear power plant, to control the nuclear reaction to produce energy.
Pressurized Water Reactor (PWR)
In a pressurized water reactor, ordinary water plays the role of a moderator as well as a coolant. First, the primary cooling circuit flows through the core of the reactor under a high pressure. The secondary circuit generates steam and drives the turbines. Since the water in the core of the reactor can reach up to a temperature of 325°C, it is kept under about 150 times atmospheric pressure to prevent it from boiling.
Pressurized Heavy Water Reactor (PHWR)
The moderator in a pressurized heavy water reactor is placed in a large tank called calandria. Horizontal pressure tubes penetrate the tank, acting as fuel channels. The flow of high pressure heavy water cools the calandria in the primary circuit. The turbines spin and produce steam in the secondary circuit. Since the tank has a pressure tube design, the reactor can be refueled by isolating each pressure tube from the cooling circuit, without actually shutting down the reactor.
Boiling Water Reactor (BWR)
The top part of the core functions with approximately 15% water as steam, in a boiling water reactor. The steam is directly transferred to the turbines through the drier plates located above the core. Since the water in a boiling water reactor is contaminated with radionuclides, the turbines are shielded by radiological protection during the maintenance of the nuclear fission power plant.