Nuclear Fission Explained: All You Need to Know

Nuclear Fission Explained: All You Need to Know

By
Grace Smoot

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Nuclear fission involves splitting apart the nucleus of an atom to release enormous amounts of energy in the form of heat and radiation. It has evolved into our second-largest source of low-carbon energy today despite facing negative public opinion. So, we had to ask: What is nuclear fission really, and how can it help mitigate climate change?

Nuclear fission is the generation of energy produced when splitting apart the nucleus of an atom. Per kWh of energy produced, nuclear fission emits 12 grams of carbon dioxide (CO2) on a life-cycle basis. It combats climate change but faces negative opinions due to nuclear waste byproducts.

Keep reading to find out all about what nuclear fission is, its global capacity, its carbon footprint, its environmental benefits and drawbacks, and how it can mitigate climate change.

The Big Picture of Nuclear Fission

Nuclear fission contributes to the avoidance of greenhouse gas (GHG) emissions from the burning of fossil fuels (e.g., coal, oil, natural gas). It is classified as a nonrenewable energy source because Uranium-235, the ingredient for nuclear fission, is a finite resource found in a concentration of 2.8 parts per million (0.7% abundance) in the Earth’s crust.

How Is Nuclear Fission Defined

Nuclear fission, one of two ways to produce nuclear energy, is the generation of energy produced when splitting apart the nucleus of an atom. 

Nuclear fission: a nuclear reaction in which a heavy nucleus splits spontaneously or on impact with another particle, with the release of energy.”

Cambridge Dictionary

All operating nuclear power plants today utilize the process of nuclear fission. Because of this, nuclear fission is commonly referred to as ‘nuclear energy’ in the data and literature. 

What nuclear fission isNuclear fission is the process by which neutrons are used to split the nucleus of an atom, which releases an enormous amount of energy in the form of heat and radiation. 
How nuclear fission worksWhen a neutron strikes the nucleus of an atom, the atomic center can break apart into pieces, thereby releasing energy in the form of radiation and heat. The heat then turns turbines and powers generators to create electricity.
The global capacity of nuclear fissionNuclear energy accounted for roughly 10% of global electricity generation in 2022, generating approximately 2,500 terawatt hours (TWh) of electricity from approximately 413 gigawatts (GW) of installed capacity. The US, China, France, Russia, Republic of Korea together represent roughly 70% of the world’s nuclear energy generation.
The carbon footprint of nuclear fissionOn a life-cycle basis, nuclear power (nuclear fission) emits 12 grams of CO2 equivalent per kilowatt-hour (KWh) of electricity produced, which is tied for the third-lowest out of all energy types.
The environmental benefits of nuclear fissionNuclear fission has a low carbon footprint, has a minimal land use impact, is energy dense, generates very little waste, promotes energy security and energy independence, and creates jobs.
The environmental drawbacks of nuclear fissionThe main environmental drawbacks associated with nuclear fission are uranium mining and nuclear waste, which can be mitigated if handled properly.
Nuclear fission and climate changeNuclear fission combats climate change by mitigating the temperature rise, sea-level rise, ice melting, and ocean acidification associated with global warming.

How Does Nuclear Fission Work

Nuclear fission is the process by which neutrons are used to split the nucleus of an atom, which releases an enormous amount of energy in the form of heat and radiation. 

How Does Nuclear Fission Actually Produce Energy

When it comes to nuclear fission, we need to start with atoms. All matter consists of atoms, each of which contains a nucleus. When a neutron strikes the nucleus of an atom, the atomic center can break apart into pieces, thereby releasing energy in the form of radiation and heat. 

Illustration of the nuclear fission process
International Atomic Energy Agency: Nuclear Fission

All nuclear fission power plants operate in the following manner:

  • The reactor starts and U-235 atoms in the reactor core split (fission), releasing heat and neutrons.
  • Neutrons fission other nuclei in the reactor core in a chain reaction, generating more heat and more neutrons.
  • Control rods contain materials that absorb some of the neutrons, helping to contain the chain reaction.
  • The heat generated turns water that surrounds the immersed reactor into steam.
  • The steam spins a turbine which drives a generator to produce electricity.

What Is the Global Capacity of Nuclear Fission

Nuclear energy accounted for roughly 10% of global electricity generation in 2022, generating approximately 2,500 TWh of electricity from approximately 413 GW of installed capacity.

Illustration from Our World in Data: Nuclear power generation
Our World in Data: Nuclear power generation

Historically, the US has led the way in nuclear energy, with 93 operating commercial nuclear reactors at 54 nuclear power plants. But more recently, China has emerged as a global leader in nuclear energy. China currently has 21 nuclear reactors under construction, two and a half times more than any other country, which will contribute an additional 21 GW of electricity. 

Some countries rely heavily on nuclear energy whilst others have not yet tapped into the resource. For example, nuclear energy provides roughly 60% of France, Slovakia, and Ukraine’s electricity, but South America and Africa get virtually no energy from nuclear. The top 5 countries (The US, China, France, Russia, Republic of Korea) represent roughly 70% of the world’s nuclear energy generation.

Illustration from Our World in Data: Nuclear power generation, 2022
Our World in Data: Nuclear power generation, 2022

The future of nuclear fission remains uncertain. Although it can produce relatively emissions-free energy and adjust its energy output to compensate for shifts in renewable energy output, nuclear fission also faces high upfront costs and negative public opinion. 

Overall, the IEA has labeled nuclear energy as ‘more efforts needed’ in their Net Zero by 2050 Scenario, a framework for the global energy sector to achieve net zero CO2 emissions by 2050 and universal energy access by 2030.

In terms of capacity additions, nuclear energy capacity must increase from 414 GW to 545 GW by 2030 to stay on track in the net zero scenario. Currently, there are about 60 nuclear reactors under construction in 15 countries, most notably in China, India, and Russia.

Illustration from International Energy Agency: Nuclear power capacity by country or region in the Net Zero Scenario, 1990-2030
International Energy Agency: Nuclear power capacity by country or region in the Net Zero Scenario, 1990-2030

In terms of funding, nuclear investment must triple to $125 billion per year to stay on track in the net zero scenario. Investment averaged only $40 billion per year from 2016-2022, but the Intergovernmental Panel on Climate Change (IPCC) predicts global investments to increase to over $100 billion per year through 2050.

Illustration from International Energy Agency: Average annual investment in nuclear power by country or region in the Net Zero Scenario, 2011-2030
International Energy Agency: Average annual investment in nuclear power by country or region in the Net Zero Scenario, 2011-2030

Going forward, nuclear energy will continue to be an important part of our energy mix. Nuclear energy helps avoid 1.5 gigatons of emissions per year and 180 billion cubic meters of global gas demand per year. In the past 50 years, nuclear energy has helped avoid over 70 gigatons of emissions

What Is the Carbon Footprint of Nuclear Fission

The carbon footprint is one of the ways we measure the effects of human-induced global climate change. It primarily focuses on the greenhouse gas (GHG) emissions associated with consumption and includes other emissions such as methane (CH4), nitrous oxide, and chlorofluorocarbons (CFCs).

Carbon footprint: the amount of greenhouse gasses and specifically carbon dioxide emitted by something (such as a person’s activities or a product’s manufacture and transport) during a given period

Merriam Webster

Basically, it is the amount of carbon emitted by an activity or an organization. This includes GHG emissions from fuel that we burn directly (e.g., heating a home or driving a car) and GHG emissions from manufacturing the products that we use (e.g., power plants, factories, and landfills). 

On a life-cycle basis, nuclear power (nuclear fission) emits 12 grams of CO2 equivalent per kilowatt-hour (kWh) of electricity produced, which is tied for the third-lowest out of all energy types.

Have a look at the illustration below to see the average life-cycle CO2 equivalent emissions of different energy sources and how they compare to nuclear.

Illustration of the Average life-cycle CO2 equivalent emissions from World Nuclear Association
World Nuclear Association: Average life-cycle CO2 equivalent emissions

When discussing the carbon footprint of nuclear fission, we must take into account carbon emissions across the energy’s building, operating, and building back phases.

The life-cycle stages of nuclear fissionEach stage’s carbon footprint
Building of nuclear fissionSome CO2 emissions from constructing the nuclear power plant, mining and processing uranium, and transporting nuclear fuel to the power plant
Operating of nuclear fissionLittle to no CO2 emissions or waste products
Building back of nuclear fissionSome CO2 emissions from transporting used fuel/radioactive material and deconstructing the power plant

Nuclear power makes up 10% of our global electricity generation. Because it is often described as an efficient, safe, and clean energy substitute for fossil fuels, understanding nuclear fission’s carbon footprint and how its carbon emissions affect the global climate change process is important.

Related: Are you interested in learning more about the carbon footprint of nuclear fission? Check it out in this article here: “What Is the Carbon Footprint of Nuclear Fission? A Life-Cycle Assessment

How Environmentally Friendly Is Nuclear Fission

The overall environmental friendliness of nuclear fission is a controversial topic. Although the process of nuclear fission produces zero CO2 emissions, the handling and disposal of nuclear waste is a serious issue. 

Environmentally friendly: (of products) not harming the environment.”

Cambridge Dictionary

Nuclear fission can reduce the effects of global warming by limiting global emissions, but uranium mining and nuclear waste are drawbacks that must be taken into consideration.

What Are the Environmental Benefits of Nuclear Fission 

Nuclear fission is expected to continue to play a key role in the clean energy movement. This is because nuclear:

  • Promotes energy security: Nuclear energy contributes to energy security by increasing the stability of our power grids. Unlike renewable energy, which faces variations in supply and demand, nuclear energy can provide a reliable and consistent source of clean energy. 
  • Promotes energy independence: Being able to produce your own electricity without the aid of foreign countries is an important step in becoming self-sufficient. For example, former President George W. Bush signed the Energy Independence and Security Act of 2007 to reduce US dependence on oil, expand the production of renewable fuels (and confront global climate change). 

What Are the Environmental Drawbacks of Nuclear Fission 

Nuclear fission does come with some drawbacks that, if handled properly, can be mitigated. The main environmental drawbacks associated with nuclear fission are uranium mining and nuclear waste.

  • Uranium mining: This process contaminates the environment with radioactive dust, radon gas, water-borne toxins, and increased levels of background radiation. Exploratory drilling and mining also heavily increase the risk of water contamination. 

Ways to minimize negative environmental impacts include the proper handling, transportation, storage, and disposal of radioactive waste to ensure that it does not leach into the environment. 

Why Is Nuclear Fission Important to Fight Climate Change

Climate change is arguably the most severe, long-term, global impact of fossil fuel combustion. Every year, approximately 33 billion tons (bt) of CO2 are emitted from burning fossil fuels. The carbon found in fossil fuels reacts with oxygen in the air to produce CO2. This warms the earth by acting as a heating blanket, and a warmer earth comes with a host of negative side effects. 

Using nuclear fission instead of fossil fuel energy helps mitigate the following negative effects of climate change:

The more we reduce CO2 emissions, the more we slow the rate of temperature rise, sea-level rise, ice melting, and ocean acidification. When these rates are slowed, the earth’s biodiversity does not have to struggle to adapt to temperature and pH changes. People will not be displaced due to the flooding of coastal areas. And icebergs will continue to provide climate regulation. 

To help keep global temperature rise below 1.5°C, as outlined in the Paris Agreement, we must shift at least 80% of our electricity generation to low-carbon sources. Over 140 countries have stated a net-zero target, covering roughly 88% of the world’s emissions. However, under current conditions, global emissions are projected to increase by 9% by 2030 instead of the 45% reduction in emissions that is needed.

Final Thoughts

Nuclear fission, one of two ways to produce nuclear energy, is the generation of energy produced when splitting apart the nucleus of an atom. Nuclear energy currently accounts for roughly 10% of our global electricity generation, and all operating nuclear power plants today utilize the process of nuclear fission. 

Despite numerous benefits, nuclear power faces an uncertain future. Although it can produce relatively emissions-free energy and adjust its energy output to compensate for shifts in renewable energy output, it also faces high upfront costs and negative public opinion. However, experts still predict nuclear energy will continue to play a key role in the clean energy movement for years to come.

Stay impactful,

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