Nuclear power: decarbonized electricity and heat production on a global scale

Nuclear power holds fantastic promise: very low-carbon, safe energy that can be produced on a large scale. However, it requires high levels of technology, and accidents can be dramatic. Here, we present the various elements that will give you an idea of the role it can play in energy transition and economic development.

  • How nuclear power plants work
  • Safety
  • Nuclear power around the world
  • Innovations in nuclear energy
  • Nuclear power’s impact on the climate and its role in reducing emissions

In short, by examining the operation of nuclear power plants, their safety, their place in the world, innovations in nuclear energy, as well as the climate impact and their interest in the energy transition, we can get a clearer idea of the role this technology can play in the energy transition and economic development.

How nuclear power plants work

The operation of nuclear power plants is based on a nuclear fission reaction, which takes place in the nuclear reactor, where atomic nuclei are split into two lighter parts, releasing energy in the form of heat. This heat is then used to heat a coolant (= gas or liquid carrying the heat). Water is the most commonly used coolant. In pressurized water nuclear power plants, water is heated in the reactor and transported under pressure through heat exchangers, where it transfers heat to another water source, producing steam. This steam drives turbines, which in turn drive generators to produce electricity. Gases such as CO2 or helium can also be used as heat carriers.

The fuel used in today’s nuclear power plants isenriched uranium, generally encased in a zirconium alloy cladding in the form of cylindrical pellets assembled into “rods”. Uranium is a radioactive element that undergoes a fission reaction when bombarded with neutrons. Uranium’s life cycle begins with mining, followed by refining, enrichment and fuel pellet manufacture. After use in the reactor, spent fuel must be removed and stored for future disposal.

The life cycle of nuclear power plants is long and complex. Building a nuclear power plant can take from 5 to 10 years, depending on its size and complexity. Once built, the plant has a useful life of several decades, after which it must be dismantled. Dismantling nuclear power plants is a complex and costly process that can take several years, and can be problematic, particularly for graphite-fired plants.

Finally, since turbines are only 30 to 40% efficient, there is waste heat, which can be recovered and recycled.

Nuclear power safety

The safety of nuclear power is often a subject of alarm, and for good reason: the worst nuclear accidents, Chernobyl and Fukushima, were terrifying events, leaving their mark on the whole world and causing hundreds of square kilometers to be closed off. Despite this, it remains one of the world’s safest sources of electricity. To understand this, it is essential to understand the risks associated with radioactivity, and the safety measures put in place to minimize these risks.

Radioactivity is often associated with apocalyptic images of dead zones and uncontrolled mutations, but in reality it is omnipresent in our environment. The doses of radioactivity generated by nuclear power plants are trivial, and we are exposed to similar doses in our daily lives. Nuclear power plants can also release radioactive elements, such as the radioactive gases produced in the event of a reactor meltdown, which generate radioactivity that can be excessive and dangerous. Nuclear safety is designed to manage this risk. There are essentially two aspects:

  • Waste management. Nuclear waste is classified according to the intensity and longevity of its radioactivity, and its management is a major concern for the nuclear industry. Plant dismantling is also a complex and costly operation, requiring special precautions to minimize the risk of contamination.
  • Plant safety. This involves preventing nuclear accidents. To achieve this, safety mechanisms are put in place, such as constant monitoring of reactors and cooling circuits, as well as containment barriers to limit radioactivity leakage in the event of an accident. Accidents are classified according to their severity on the INES scale, which ranges from 0 to 7. Events of severity 0 to 3 are incidents, while those of severity 4 to 7 are accidents. The most notable nuclear accidents were at Three Mile Island, Chernobyl and Fukushima.

Despite this, nuclear power plants remain a reliable and safe source of electricity, with a limited number of accidents in relation to the number of plants worldwide. Above all, innovations will make them even safer, with passive cooling systems “built in” to the operation of the nuclear reactor itself.

Nuclear power in the world

Nuclear power is an energy source used worldwide to generate electricity, with a market share of around 10% in 2021, according to the International Energy Agency(IEA). Although its share of the global energy mix has fallen slightly in recent years, the use of nuclear power remains significant in some countries.

Here are a few key figures illustrating nuclear power’s place in the world:

  • According to the International Atomic Energy Agency (IAEA), there were 443 nuclear reactors in operation worldwide at the end of 2020, with a total electricity generation capacity of 392 GW.
  • The countries producing the most nuclear power are the United States, France, China, Japan, Russia and South Korea.
  • In France, nuclear power accounts for around 70% of electricity production. It is the country that uses the most nuclear power as a proportion of its total electricity production.
  • In China, which is experiencing strong economic and demographic growth, the share of nuclear power in electricity generation has risen from 2% in 2010 to almost 5% in 2021, and is set to continue rising in the coming years.
  • On the other hand, some countries have decided to phase out nuclear power, such as Germany, which aims to close all its power plants by 2022.

Innovations in nuclear power

There are several major innovations that could revolutionize nuclear power. First and foremost, small modular reactors(SMRs) could speed up and facilitate plant design, improve reliability, reduce costs and decentralize nuclear power generation. The 4th generation of nuclear reactors is just around the corner. One of its major improvements would be to enable fast-breeder reactors, which would go a long way towards solving the problem of nuclear waste and multiply fuel availability by several dozen times. Finally, the most important innovation, but also the furthest away: nuclear fusion. It promises virtually infinite energy, but is still at a highly experimental stage, with an industrial prototype not even envisaged for several decades.

Nuclear power and climate

Finally, we’ll be looking at the interactions between nuclear power and climate. We’ll be answering a number of questions:

  • Is nuclear power really low-carbon?
  • Is climate change a problem for nuclear power generation?
  • Can nuclear power be a fast enough response to climate change?