Nuclear energy is the energy released during the transformations that occur in the atomic nucleus. In a nuclear power plant, this energy is not directly converted into electricity. First, heat is produced by controlled fission reactions; This heat is used to create steam, rotate the steam turbine, and generate electricity in the generator connected to the turbine.
In this respect, a nuclear power plant is similar to other thermal power plants that use heat to produce electricity. The main difference is that the heat source is not the burning of coal or natural gas, but nuclear fission within the reactor.
What is nuclear fission?
Fission is the splitting of a heavy atomic nucleus into smaller nuclei. When a neutron is absorbed by a fissionable nucleus, the nucleus can fission. In this process, energy that can be converted into heat and new neutrons are released.
The fission of the released neutrons in other nuclei creates a chain reaction. In power reactors, this reaction is kept under control. The aim is for the reactor to produce the required heat in a stable and predictable manner.
How does electricity production occur step by step?
1. Heat is generated in the reactor core
Fuel is placed in the reactor core in the form of fuel rods and fuel bundles. The energy released during fission raises the temperature of the fuel and the surrounding coolant.
2. Heat is transferred to water
Depending on the reactor design, water can boil inside the reactor or be kept in liquid form under high pressure and transfer its heat to water in a separate circuit. Separation of primary and secondary water circuits in pressurized water reactors is one of the basic features of this system.
3. Steam rotates the turbine
The steam produced rotates the turbine shaft as it passes through the turbine blades. The energy conversion up to this point proceeds from nuclear energy to heat and then to mechanical energy.
4. Generator produces electricity
The generator connected to the turbine shaft converts mechanical energy into electrical energy. The electricity produced is transferred to the grid through transformers and transmission lines.
5. Steam is converted back into water
The steam coming out of the turbine is cooled in the condenser, converted back into water and sent back to the cycle. The white cloud seen from cooling towers consists mostly of condensed water droplets; It is not smoke.
What are the basic components of the reactor?
- Fuel: It contains the material in which fission occurs.
- Moderator: In some reactors, it helps sustain the chain reaction by slowing down neutrons.
- Cooler: It carries the heat generated in the reactor core.
- Control sticks: It helps adjust reactor power by absorbing neutrons.
- Reactor vessel and safety structures: It keeps fuel and reactor systems within certain physical limits.
- Turbine and generator: It converts the steam movement obtained from heat into electricity.
Not every reactor design uses the same components in the same way. There are significant design differences between pressurized water, boiling water, heavy water and gas-cooled reactors.
Are a nuclear reactor and a nuclear bomb the same thing?
No. A power reactor is designed to drive a controlled chain reaction to produce heat. Fuel properties, system geometry, control mechanisms, and operating conditions differ from how a nuclear weapon operates. The statement “both have fission” does not mean that the two systems are the same.
Frequently asked questions
What can a nuclear power plant produce other than electricity?
With appropriate designs, reactor heat can also be used in non-electrical applications such as district heating, industrial process heat or water purification.
Why is water used in a nuclear power plant?
Water can serve as both a heat carrier and a moderator slowing down neutrons in many reactor designs. However, not all reactors use the same coolant or moderator.
Does heat production stop immediately when the reactor is shut down?
After the chain reaction is stopped, residual heat continues to be generated due to the radioactive decay of fission products. Therefore, post-shutdown cooling is one of the key issues in reactor safety.
Resources
- IAEA, Fundamentals of Nuclear Power: https://nucleus-qa.iaea.org/sites/graphiteknowledgebase/wiki/Guide_to_Graphite/Fundamentals%20of%20Nuclear%20Power.aspx
- IAEA, Design of a Nuclear Reactor — Basic Professional Training Course: https://gnssn.iaea.org/main/bptc/BPTC%20Module%20Documents/Module04%20Design%20of%20a%20nuclear%20reactor.pdf
- IAEA, Radiation, People and the Environment: https://www.iaea.org/sites/default/files/radiation0204.pdf