SMR: small nuclear reactors

SMR: small nuclear reactors

Small Modular Nuclear Reactors (SMR) are an innovation in nuclear technology that is gaining popularity in the energy industry. These mini reactors offer many advantages over conventional large nuclear reactors, making them an attractive option for future power generation.

What is an SMR?

SMRs are nuclear reactors designed to be smaller in size and power generation capacity than traditional reactors. Their modular design allows them to be built in a factory and then transported to the site of use, significantly reducing costs and construction times.

These reactors are also designed with a focus on safety, efficiency, and operational flexibility.

Mini nuclear reactors

On the other hand, mini nuclear reactors are compact versions of conventional nuclear reactors, designed to generate a relatively low amount of energy.

These microreactors, as they are also known, have a power output that generally ranges from a few electrical kilowatts (kWe) to several electrical megawatts (MWe), being considerably smaller than Small Modular Nuclear Reactors (SMR).

Advantages of small nuclear reactors

This type of reactors offers several advantages that make them an increasingly attractive option in the current energy landscape. These advantages derive from both its specific design and its ability to address common challenges in the energy industry.

Below are some of the main advantages:

  1. Small dimensions and modularity: As the name indicates, SMRs are smaller compared to conventional nuclear reactors. This feature allows them to adapt to a variety of locations and environments, including areas where it would not be feasible to build large-scale nuclear reactors. Additionally, its modular design facilitates mass manufacturing and reduces costs associated with construction and logistics.
  2. Deployment flexibility : Small reactors can be deployed incrementally to meet energy demands at different scales and contexts. This makes them ideal for both large power grids and remote communities or islands that require a reliable power source but do not have access to large-scale infrastructure.
  3. Reduced construction costs and times : Factory manufacturing and transportation of SMRs in prefabricated units help reduce construction costs and times compared to conventional nuclear reactors, which are typically custom projects that can face significant delays. .
  4. Increased Safety: SMRs are designed with a focus on safety, with passive systems and inherent features that minimize the risks associated with nuclear operations. These include passive cooling systems and the ability to automatically shut down in an emergency, reducing the need for human intervention.
  5. Lower environmental impact : Although nuclear energy is not completely free of environmental impact, SMRs offer the possibility of generating electricity with low carbon emissions, which contributes to the mitigation of climate change. In addition, its smaller physical footprint and the ability to integrate into existing electrical networks reduce the environmental impact and the need for new infrastructure.
  6. Improved waste management: Although all nuclear reactors generate radioactive waste, modular nuclear reactors can offer more efficient waste management thanks to their smaller size and fuel requirements. Some designs are also aimed at reducing the amount and toxicity of nuclear waste produced.


A small modular nuclear reactor (SMR) operates following the basic principles of nuclear fission.

At its core, the reactor contains nuclear fuel, such as uranium-235, which when bombarded by neutrons splits into smaller nuclei, releasing a large amount of energy in the form of heat. This heat is used to heat a cooling fluid, which can be water, helium or sodium, depending on the reactor design. The cooling fluid absorbs heat from the reactor core and transports it to a heat exchanger, where it heats water at high pressure to produce steam. This steam drives a turbine connected to an electrical generator, thus converting thermal energy into electrical energy.

SMRs can be designed in different variants, such as pressurized water reactors (PWR) or boiling water reactors (BWR). In addition, SMRs are usually equipped with safety and control systems to ensure their safe and reliable operation, including emergency cooling systems and automatic shutdown systems in case of overload.

The electrical power of an SMR

The power output of a small modular nuclear reactor is considerably lower compared to a conventional nuclear reactor.

While conventional nuclear reactors typically have a power generation capacity ranging from several hundred to more than a thousand electrical megawatts (MWe), SMRs typically have a power output ranging from a few electrical megawatts to approximately 300 MWe.

This difference in power output is mainly due to the smaller size of SMRs and their modularity capability, which allows them to adapt to different scales of power demand and diverse locations.

Publication Date: April 22, 2024
Last Revision: April 22, 2024