Nuclear Energy Definition, Reactions, Sources, Benefits, and Limitations

Nuclear Energy is energy which is contained in the nucleus of an atom, and which can be harnessed by atomic fission or fusion.

The overall definition of Nuclear Energy is given in this article, according to the outline below;

-Nuclear Energy Definition

-Nuclear Energy and Nuclear Reactions

-How Nuclear Energy is Produced: The Generation of Nuclear Energy

-Sources of Nuclear Energy

-Nuclear Energy and the Environment

-How Nuclear Energy is Used: The Uses of Nuclear Energy

-Benefits of Nuclear Energy

-Limitations of Nuclear Energy





Nuclear Energy Definition

Nuclear energy is energy which is stored in the nucleus, at the core of an atom [8].

The central position of nuclear power in an atom ensures that the atom sustains its natural structure and composition.

Atoms themselves occur in all matter. They are simply the building blocks (or smallest representative components) that make up matter [4]. Each atom is held in shape by nuclear energy which exists at the center of the atom. As this implies, by splitting the atom, nuclear power is released, which can be used for other important purposes.

We can also describe nuclear power as the binding energy at the core of an atom. This means that its purpose and function are to hold the essential components of the atom together.

It also implies that in order to access nuclear power, it is important to break the bond(s) at the core of atoms. By inference, therefore, nuclear energy is the outcome of some form of dissociation or disintegration within the atomic structure of matter.


Nuclear Energy and Nuclear Reactions

As we have already seen, atoms are the tiny components that make up matter. These atoms themselves are made up of components that include protons, electrons and neutrons [18].

These components are charged, and must be held firmly together to keep the atom in one piece. Nuclear power is the enormous energy which binds these different components together, holding them firmly to the core of the atom.

It is necessary to break the bonds which hold the components of the atom together, in order to release nuclear power. In general, atomic bonds are broken through nuclear reactions.

Nuclear reactions are simply reactions that involve the dynamics of energy in the nucleus of atoms. This may occur in the form of energy absorption or release, and is associated with changes in the structure of the atom. By causing energy dynamics in the nucleus of an atom, nuclear reactions directly affect the structure and stability of the atom. The difference between nuclear reactions and normal chemical reactions is summarized in the table below;


Nuclear Reactions Normal Chemical Reactions
Involve changes in the nucleus of atoms Involve a rearrangement of electronic configurations
Usually leads to the formation of a new chemical element Usually leads to the formation of a chemical molecule or element
Generally involve massive amounts of energy  Involve relatively small amounts of energy
Mass is usually lost in the process of nuclear reactions Mass is generally conserved in normal chemical reactions
Nuclear reactions are generally irreversible Normal chemical reactions are generally reversible
The identity of individual elements involved is usually changed in the process The identity of individual elements is preserved in normal chemical reactions
Involve all components of the atom (proton, neutron, electron) Involve mainly electrons
External factors like temperature, pressure and catalysts, have little or no effect on the reaction External factors have significant effect on the reaction


There are numerous types of nuclear reactions. However, with respect to the production of energy, three main types of nuclear reactions can be identified. These are; Nuclear Fusion, Nuclear Fission, and Radioactive Decay [2].

1). Nuclear Fusion (as a Potential Source of Nuclear Energy)

Nuclear Fusion is a form of nuclear reaction whereby two or more nuclei of atoms combine together, to produce one or more nuclei and subatomic components (that is; protons or neutrons) [1].

It is important to note that the atomic nuclei which are formed in nuclear fusion, are different from the original atoms which were initially involved in the reaction.

Another way to describe nuclear fusion, is as a collision of two or more relatively light atomic nuclei, to form one or more relatively heavy nuclei [9].

A good example of nuclear fusion can be seen in the release of energy in the form of heat, from stars. In these stars (which include the Sun), nuclear power is released when two light (isotopic) hydrogen nuclei collide and combine to form one relatively heavy, isotopic helium nucleus [21].

Nuclear Energy, Nuclear Fusion, Nuclear Reaction
Fusion of Hydrogen Isotopes to Produce Helium with release of Nuclear Energy


Nuclear power release, in the process of nuclear fusion, generally causes a change in mass. This is because energy is either released or absorbed in large quantities in the course of nuclear fusion.

The amount of energy released (or absorbed) in nuclear fusion is generally up to four times as much as that which is released in nuclear fission. However, this type of nuclear reaction is not used in commercial production of nuclear power, because it requires extremely high temperatures (up to 10^7K-10^9K) [17] and high pressures (up to 10^9 ATM) to occur. For this reason, nuclear fusion is also called Thermonuclear Reaction [11].

2). Nuclear Fission (as a Potential Source of Nuclear Energy)

Nuclear fission is simply a reaction in which a relatively heavy atomic nucleus splits into two or more smaller nuclei [5].

In the process of nuclear fission, neutrons and gamma rays are usually produced. This leads to the generation of massive amounts of energy, that usually occurs in the form of heat [6].

Another way to define nuclear fission, is as the subdivision of a relatively heavy atomic nucleus, like Plutonium or Uranium, into two or more nuclei that are often fairly equal in mass, with the release of a large magnitude of energy.

So far, the production of nuclear power by man has been carried out mainly through nuclear fission. Commercially, nuclear fission is simulated within a nuclear reactor (or nuclear power/ nuclear reaction plant). Examples of heavy atoms which are used in the process include Plutonium and Uranium [16].

3). Radioactive Decay (as a Potential Source of Nuclear Energy)

Radioactive decay is a type of nuclear reaction which occurs when energy is released or emitted from the nucleus of an unstable atom. The energy released by the unstable atom in the process of radioactive decay is usually in the form of radiant heat.

Other terms used to refer to radioactive decay include radioactivity, nuclear decay, nuclear disintegration and radioactive disintegration. Materials which undergo radioactive decay are generally called radioactive materials, and they include Radon, Uranium, Thorium, Polonium, Cesium, and Plutonium [10]. These materials are composed of atoms whose nuclei are unstable.

Although significant magnitudes of nuclear power can be produced through radioactive decay, the amount of energy produced is generally not as much as that produced by nuclear fission or fusion. For this reason (among others) radioactive decay is not used as a means of generating energy.


How Nuclear Power is Produced

In simple terms; nuclear power is produced from nuclear fission.

This nuclear fission is made to occur under fairly-controlled conditions, in a nuclear power plant (or nuclear reactor). A nuclear plant or reactor, is a technological system, which can facilitate and manage nuclear fission reactions under predetermined conditions, to produce usable energy.

In these nuclear power plants, the radioactive substance which serves as a fuel to drive the system and the reactions, is usually Uranium. This is because of the highly-reactive and energetic properties of the element. One of the Uranium isotopes; U-235, is the most commonly used fuel for generating nuclear energy, because its atomic nuclei spilt easily compared to other Uranium Isotopes.

Uranium is usually fed into the nuclear reactor in the form of pellets. The splitting of the Uranium atomic nuclei in the reactor (nuclear fission) leads to the release of large amounts of heat. This heat is in turn used to produce steam (by heating water), which drives a steam turbine, to produce electricity from nuclear energy.

The pellets of uranium which are fed into the nuclear reactor, are composed of highly refined uranium which has been extracted from rocks by mining. Each of these pellets is believed to contain nuclear power that is equivalent to 150 gallons of petroleum [5]


In summary, the process of generating nuclear power can be given in a series of defined steps, as follows;

Step 1: Nuclear Reaction

In this first step, the uranium pellets (nuclear fuel) are fed into the nuclear reactor. They are then bombarded by neutrons which are fired at them. These neutrons themselves are mostly derived from splitting Uranium-fuel atoms [13].

Each Uranium 235 (U-235) atom absorbs a neutron and is converted briefly into uranium 236 (U-236) isotope. On further bombardment with neutrons, the nucleus of the Uranium atom is split to give rise to other elements. In a typical scenario, uranium may split to give Xenon-139 (Xe-139), Strontium-95 (Sr-95), and two neutrons. The mass which is lost in the process is released as large quantities of nuclear energy, usually in the form of heat. 

The first stage involves a chain reaction, because as the Uranium atomic nuclei split, each one releases more neutrons which collide with other atoms and cause continuous and successional nuclear fission.

Step 2: Nuclear Energy is Used to Heat Water

After the splitting of the Uranium atoms and the release of nuclear power as heat in the first stage, this heat is applied to water.

To make the heating process effective and efficient, the water is usually housed in a delineated vessel or chamber in the nuclear reactor system. Applied heat is usually up to 300°C. However, the water is usually heated under high pressure to prevent its complete vaporization while heating.

Step 3: Production of Steam

In order to produce steam, the heated water is channeled to a steam-generator under high pressure using a coolant pump. 

Within the steam-generator, the pressure is reduced, allowing the heated water to vaporize and form steam.

Step 4: Steam Turbine-Mobilization and Electricity-Generation

After steam has been produced, it is passed through a turbine system under pressure, and helps to drive (spin) the turbine(s).

This produces mechanical energy which is in turn used to drive a generator through an interconnected shaft. The rotating shaft causes a coil to rotate in a magnetic field, thereby generating electricity through the principle of electromagnetic induction.

Transmission of the electricity generated is done with the help of electric power lines, and a transformer is used to convert the electricity to high voltage before it is transmitted. At the end of the overall process of electricity-generation, the steam is usually cooled using cold seawater [19], and recycled for further use.


Nuclear energy, Nuclear reactor, Nuclear power plant
Steps In the Generation of Nuclear Energy in A Reactor

Sources of Nuclear Energy

Nuclear power is produced from nuclear reactions.

Commercially, nuclear reactions are driven by reactive, radioactive elements. These nuclear elements are generally referred to as nuclear fuels.

The most commonly used nuclear fuel for generating nuclear energy is Uranium.

As earlier stated, Uranium is extracted from rocks by mining. It is a non-renewable resource, because it occurs in limited quantity in the Earth’s crust. This implies that nuclear energy itself is NOT a renewable form of energy. However, nuclear power is clean, and therefore has a high degree of sustainability.

Uranium 235 (U-235) is a highly reactive isotope of Uranium which is often used as nuclear fuel because of its ability to undergo nuclear fission with relative ease. After it has been extracted by mining, the Uranium usually needs to be refined before it is used to generate nuclear energy. 


Nuclear Energy and the Environment

We refer to nuclear power as ‘clean’ and ‘sustainable’ because there is no significant gaseous emission in the process of generating this form of energy.

This gives it an obvious advantage over fossil fuels, since there is no significant emission while generating nuclear power, in contrast to fossil fuel exploration and usage.

However, there are other ways by which nuclear power affects the environment.

One of these is through the process of mining and extraction of nuclear fuels. Because large amounts of energy must be used to extract uranium ore from rocks in the earth, the process of acquiring uranium pellets will lead to significant greenhouse gas emissions.

Radioactive waste is also produced in the process of generating nuclear power [15]. This is a serious environmental concern because radioactive wastes are potentially harmful to human health and can cause environmental pollution.

Asides the direct, potential consequences to the environment, nuclear power generation also poses some significant risks. This is due to the fact that massive amounts of energy and matter are involved in nuclear reactions, and errors in the management of nuclear reactors may therefore lead to hazardous events.


Uses of Nuclear Power

1). Electricity Generation

Since the year 1990, nuclear energy has been used to generate approximately 20 percent of electricity in the United States.

By December 2020, there were more than ninety (90) nuclear reactors in 28 states in the US, spread across 56 nuclear power plants. Nuclear energy constitutes almost 60 percent of the total supply of clean (zero-carbon/zero-emission) energy.

Across the world, more than 30 countries harness nuclear energy for their power needs. The most common use for nuclear energy in these countries is electricity-generation.

2). Medical Study, Treatment and Diagnosis

Radiation, which is equivalent to nuclear energy, is used extensively in the field of medicine. This includes radioscopic applications for studies and diagnosis of various health conditions, x-ray imagery, as well as cancer and tumor treatment.

3). Space Exploration

Space exploration has been greatly facilitated by the development of nuclear energy.

This is mainly through the use of Radioisotope Power Systems (RPSs) to drive space crafts [14]. Radioisotopes like Plutonium have been used extensively to generate electricity for powering space crafts and satellite systems.

Because of the long-term, sustainable nature of nuclear energy, such space crafts are able to remain functional for many years without need for direct control or maintenance. An example is the Voyager 1 satellite, which has been in operation since its launch in the year 1977.

4). Agricultural Industry

Irradiation (nuclear energy) is used in insect-pest control, in the agricultural sector.

The method is also referred to as Sterile Insect Technique (SIT) and is an environment-friendly method of controlling pests, compared to other known methods [3]. As the term implies, irradiation sterilizes insect pests and makes it impossible for them to reproduce and multiply, thereby reducing their numbers and ultimately eliminating them. 

Nuclear power, through irradiation, is also used to preserve food [7]. This is because radiation (nuclear energy) destroys harmful microbes like bacteria in food, without having any notable effect on the nutritional value of the food materials. The use of irradiation saves costs and prevents potential problems involved in refrigeration or applying chemical preservatives. 

5). Desalination of Water

Safe water for drinking and other domestic purposes is a major need of the human population [20].

Through effective desalination, large volumes of purified water can be made available. Desalination plants however require large magnitudes of energy to function, and this can be provided in the form of nuclear power. The use of nuclear energy to power desalination plants is known as Nuclear Desalination.

While other sources of energy like fossil fuels are also used to power desalination plants, nuclear desalination (the use of nuclear energy) is relatively economical option.

6). Investigation

Nuclear power is used for analytical purposes in investigations of all forms, including investigations related to crime.

This is possible because nuclear analysis is generally of high-sensitivity and is non-destructive in nature [12]. It can therefore be used to observe very minute details of a sample.

The use of nuclear energy in investigation is referred to as ‘Nuclear Forensics’. Through nuclear forensics, the smallest traces of elements in samples like saliva, tape, glass, lead, metals, gun powder or hair can be analyzed. This approach makes it possible to carry out more accurate and effective investigations.


Benefits of Nuclear Energy

1). Clean Source of Energy

As earlier stated in this article, nuclear power is zero-carbon/zero-emission in nature. This means that it is fairly clean and has no significant environmental effects.

On a yearly basis, nuclear power generates approximately 800 billion KWh of electricity in the United States. By doing so, hundreds of millions of tons of CO2 as well as other greenhouse gases are prevented from entering the atmosphere per year. This is an effective step in reducing the severity and rate of global warming.

2). Low Operational Cost

While the initial building and commissioning of a nuclear power plant involves high expenditure, the subsequent costs are relatively low.

In order to maintain and operate nuclear power plants, minimal investment (compared to fossil fuel plants) is required. This implies that the cost of generating electricity from nuclear energy is fairly economical, and cost-effective.

Also, nuclear energy is generated from nuclear fuels which are not at a high risk of economic inflation like other sources of energy.

3). Highly Dense

Compared to other sources of energy like fossil fuels, nuclear power has the advantage of being highly dense.

Through nuclear fission, large magnitudes of energy can be produced from relatively small masses of nuclear fuel. This makes nuclear energy to be many times more efficient than most other forms of energy. As a result of its high energy-density, nuclear power consumes less fuel and produces less waste than other conventional forms of energy.

4). Reliable Form of Energy

Nuclear power is considered to be a reliable form of energy because it does not depend on external, instantaneous factors like the weather condition. This is an advantage over other forms of energy like wind and solar.

Also, because of the high energy-density of nuclear fuels, they are generally capable of producing nuclear power consistently, for a prolonged period of time. Most nuclear plants operate on a 24/7 basis and need re-fueling at intervals of more than one year. Because such consistency can hardly be achieved from other energy sources, nuclear energy is viewed as one of the most reliable forms of energy.

Because of the reliability and sustainability of nuclear energy, it is also used as a supportive energy source for renewable energy technologies as well as fossil fuel power plants. When these alternative energy sources are not productive, electricity can be generated from nuclear energy to compensate.

5). Available in Sufficient Supply

While it is clear that Uranium is not a renewable resource and therefore occurs in limited quantity on Earth, the estimated volume of this nuclear fuel which is still available is sufficient to be utilized for several decades to come.

Asides Uranium, other potential nuclear fuels are being discovered and developed. This is a huge improvement on the limitation posed by fossil fuels.

6). Creates Jobs and Supports the Economy

In the United States, up to 500,000 jobs have been created by the nuclear energy sector so far. Similar (and even greater) numbers of employment opportunities have been created by the nuclear energy sector in other countries.

Economic growth is also supported by investments and developments in the field of nuclear energy. Through tax revenue, all sectors of the economy benefit from the nuclear energy sector to the tune of several billions of dollars per annum.


Limitations of Nuclear Energy

1). Adverse Environmental Impacts

Although the direct generation of nuclear power does not significantly produce greenhouse gas emissions, there are other important aspects of nuclear energy development which affect the environment.

One of these is the mining and extraction of nuclear fuels. which requires large amounts of energy and releases greenhouse gases in large volumes into the atmosphere. Mining and refining or nuclear fuel also exposes the environment to erosion, and radioactive wastes that can cause pollution hazards.

The construction of nuclear power plants can also disrupt natural ecosystems and habitats.

2). The Initial Cost of Building  Plants is High

As has already been stated, nuclear power plants demand high expenditure for their initial construction.  This is a serious limitation, as it often discourages stakeholders and potential investors from embarking on nuclear energy projects (that could be immensely useful to the society).

Asides the initial cost of building which amounts to billions of dollars, nuclear power plants also require significant investment in measures to manage potentially hazardous waste that is produced in the process of generating energy. Other discouraging factors include regulations and policies which must be met.

3). Safety Risks

It is impossible to overlook the fact that nuclear energy is closely associated with the prospect of severe safety hazards.

This association is due to different factors. One of such factors is the actual occurrence of nuclear disasters, such as the Fukushima nuclear hazard and the Chernobyl disaster, both of which have been responsible for thousands of human casualties, and have had long-term ripple effects on the health of the population.

Nuclear weapons are also considered to be related to nuclear power, and the development of such weapons implies that nuclear power itself is a potential weapon of mass destruction.

With respect to national security concerns, nuclear power plants have been identified as one of the potential targets for terrorist attacks and other forms of social conflict. As a result, the area around such plants is usually placed under heavy security.

These conceptions of security threats, that are associated with nuclear power, have seriously hampered the potential growth and development of this form of energy in general. They also imply that the use of nuclear energy may be equivalent to placing the public at the risk of various forms of disaster.

4). Non-Renewable

Given the increasing importance of sustainable development and the need to develop and improve on renewable technologies, nuclear energy may be at a disadvantage.

Although nuclear energy generation is generally clean and environment-friendly, it is not a renewable form of energy. This is simply because nuclear fuels like Plutonium, Thorium and Uranium do not occur in unlimited supply.

What this implies is that nuclear power cannot be used as an ultimate solution to the energy need on Earth. It is, rather, only a temporary source of energy.



Nuclear energy is energy which is contained in the nucleus (at the core or center) of an atom. It is generally released when the nucleus of the atom is split or disintegrated through nuclear reactions.

There are three main types of nuclear reactions, which include nuclear fission, nuclear fusion and radioactive decay. These reactions all differ from normal chemical reactions by involving atomic disaggregation and the release of nuclear energy.

Nuclear fission is the main process used by humans to derive nuclear power. This is because it does not require extreme temperature and pressure compared to other nuclear reactions, and can produce a significant amount of nuclear energy.

In order for nuclear energy to be produced commercially, a nuclear reactor must be used. This is a system which simulates nuclear reactions under well-controlled conditions. Nuclear fuels are the radioactive materials whose atoms are split in the nuclear reactor to produce nuclear power. The most common example of these is Uranium-235 (U-235) which is widely used due to its ease of atomic splitting when bombarded with neutrons.

In a nuclear reactor, nuclear power is typically produced in a series of chain reactions. This energy is harnessed in the form of heat, which is used to produce steam and subsequently to drive a steam turbine that in turn produces electricity.

Nuclear power has the notable advantage of being clean (that is; producing no significant greenhouse emissions) while it is being harnessed. It is also highly dense, relatively cost-effective, versatile and reliable.

The known applications of nuclear power include agricultural pest control and food preservation, nuclear forensics, electricity generation and medical diagnosis/treatment.

There are however some limitations. One of these is the massive cost of building nuclear plants and designing nuclear reactors. Others include safety challenges and potential hazards, environmental pollution risks and radioactive waste.

Nuclear power is also not renewable, due to the fact that nuclear fuels like Uranium are not available in unlimited supply. This means that the use of nuclear power may not be a permanent energy solution for our society.



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