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How Does a Nuclear Power Plant Work

Abhijit Naik
Nuclear power is being pitched as one of the best alternative sources of power, but at the same time, it has been subject to severe criticism owing to the safety of nuclear power plants and the waste generated by them.
Nuclear power constitutes a significant chunk of power required to produce electricity across the world. With incidents like the Chernobyl disaster, all the necessary precautions are taken to ensure that the modern nuclear power plants are safe.
In fact, the whole plant is encased within a very thick dome shaped structure as one of the safety measures.

How do Nuclear Power Plants Work?
Nuclear power plants are powered by uranium. In a process known as nuclear fission, uranium atoms are split to produce large amount of energy which is eventually converted to heat. The enormous amount of heat created in this process boils the water to produce steam which is used to rotate turbines.
These turbines, in turn, spin the shaft of the generator. As the generator gets into action, the coils of wire within the generator are spun in a magnetic field to produce electricity. A nuclear reactor maintains and controls the nuclear reaction in the plant to produce energy.
There are various types of nuclear reactors, such as the Pressurized Water Reactor (PWR), Boiling Water Reactor (BWR), Pressurized Heavy-water Reactor (PHWR), Advanced Gas-cooled Reactor (AGR), etc.

Pressurized Water Reactor (PWR)

In pressurized water reactors, ordinary water is used as the moderator as well as coolant. The primary cooling circuit flows through the core of the reactor under a high pressure, while the steam generated in the secondary circuit drives the turbines.
The water in the core of the reactor can reach a temperature of 325 °C and therefore, it has to be kept under about 150 times atmospheric pressure to prevent it from boiling.

Pressurized Heavy-water Reactor (PHWR)

In pressurized heavy-water reactors, the moderator is located in a large tank known as calandria. This tank is penetrated by horizontal pressure tubes which act as fuel channels. The calandria is cooled by the flow of high-pressure heavy water in primary cooling circuit.
The steam, which drives the turbines, is generated in the secondary circuit. Owing to its pressure tube design, the reactor can be refueled by isolating each pressure tube from the cooling circuit. There is no need to shut it down to refuel it.

Boiling Water Reactor (BWR)

In boiling water reactors, the top part of the core operates with approximately 15% water as steam. This steam goes directly to the turbines via drier plates located above the core. In these reactors, the water around the core is most often contaminated with radionuclides.
Therefore, the turbines have to be shielded by radiological protection during maintenance of the nuclear fission power plant. The expenditure saved owing to the simple design on this nuclear reactor, is spent on this shielding activity, thus balancing the expenditure incurred.
In the United States, pressurized water reactors and boiling water reactors are used in nuclear power plants. Though there exist a few security concerns about the operations of these plants, they are necessary if we are to cope with the ever-increasing energy requirements.
Owing to low levels of emission, this cost-effective source of power is steadily becoming popular. In fact, the use of nuclear energy for electricity production is expected to increase by 20% by 2030.