What are Small Modular Reactors (SMRs)?

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Small Modular Reactors, the term may seem like scientific jargon but the concept is very easy to grasp. SMRs involve a nuclear process that helps generate electricity and has several other uses. What puts the limelight on SMRs is that it is environmentally friendly. We will be discussing more about SMRs in this article, like what are Small Modular Reactors, how is energy produced through SMRs, its uses, pros and cons, hybrid energy system, and ongoing development projects.

So, without delaying any further, let us get to know about SMRs in detail.

What are Small Modular Reactors?

  • Small Modular Reactors are advanced nuclear reactors that are built for the production of electricity. It is smaller in size than conventional nuclear reactors and greater in size than microreactors. Due to its smaller size, it is referred to as a “small modular reactor”.
  • Small Modular Reactors produce up to 300 MW (e) of electricity and less than 1000 MW (th) of thermal power. It produces 1/3 rd of the energy produced by a conventional nuclear reactor.
  • The parts of an SMR are modular i.e., they can be factory-assembled, shipped and operated at a separate site.
  • Since the Small Modular Reactors are transportable to different locations, they can be installed in remote areas. Moreover, it is also suitable for grids with limited capacity.
  • Small modular reactors do not follow a standard design rule. They have scaled-down versions of existing designs and generation IV designs. These designs vary because each of them aims for economic viability.
  • Some examples of proposed SMRs include thermal-neutron reactors, fast-neutron reactors, molten salt reactor models, and gas-cooled reactor models.
  • Water is normally used as a coolant in an SMR but other coolants such as molten salt, gas, and liquid metal are also used.
  • The licensing process of developing an SMR is quite tedious as the focus is typically on conventional reactors. However, the U.S. Advanced Reactor Demonstration Program took the initiative to license two SMRs during the 2020s.

Uses of Small Modular Reactors

Small Modular Reactors are used in the following processes:

  • Electricity Generation

Non-electric applications:

  • Heating
  • Water Desalination
  • Hydrogen fuel production
  • The energy produced through SMRs is useful for industrial applications.

How do small modular reactors produce energy?

  • Small modular reactors produce energy with the help of reactors. It harnesses the power of nuclear fission to generate heat that produces energy.
  • Nuclear fission is the process of splitting the nucleus of an atom into smaller nuclei. During the splitting process, a large amount of heat and radiation is produced. This ensures a chain reaction that needs to be sustained to produce nuclear power.
  • Thermal-neutron reactors are the widely used SMRs when compared to Fast-neutron reactors.
  • Thermal-neutron reactors use uranium as the fissile material and Fast-neutron reactors use plutonium. Thermal-neutron reactors are dependent on moderators to reduce the speed of the moving neutrons. On the other hand, Fast-neutron reactors are dependent on nuclear fuel to absorb the fast-traveling neutrons.

Pros and Cons of Small Modular Reactors

Pros of SMRs/SMRs vs Traditional Nuclear Reactors

  • Small modular reactors produce up to 300 MW of electricity. Traditional nuclear reactors produce 1000 MW of electricity.
  • With SMRs, you can have zero-carbon emissions which is not the case in traditional nuclear reactors.
  • The construction time in the case of SMRs is less than that of conventional nuclear reactors.
  • SMRs are comparatively smaller in size than traditional ones. As a result, they can be easily transported to their desired location and installed subsequently. On the other hand, typical nuclear reactors are heavier and cannot be relocated to other locations.
  • The cost and construction time for traditional nuclear reactors is more than for small modular reactors. For example, an SMR may cost somewhere between $100 million to $2 billion whereas traditional ones might require $ 7 billion.
  • They are flexible in power generation and can cater to a wide range of users and are used in non-electric applications as well. They can replace the production of energy through traditional means like the burning of fossil fuels. As a result, the SMRs will help mitigate environmental problems.
  • Fast neutron reactors which is a type of SMR can reuse fuel taken from depleted uranium sources. This helps eliminate toxic wastes from nuclear reactors faster. A traditional nuclear reactor is not equipped with such an advantage.
  • SMRs do not overheat because they have smaller cores. On the other hand, traditional nuclear reactors have bigger (10 metres high) and heavier (1400 tonnes) cores and tend to overheat.
  • SMRs are more secure than conventional nuclear reactors. Due to its passive safety features, there is less manual labour required to ensure operational efficiency. However, some conventional nuclear reactors also deploy such safety features.

Cons of SMRs

  • SMRs are not cost-effective because creating thousands of SMRs for reducing factory costs will be heavier on the price. Moreover, there will be additional costs on designs in the absence of a single standard design.
  • The parts of the SMRs may need to be exchanged or replaced, achieving which is a challenging task.
  • In some places like Ontario, electricity produced through solar and wind power is less costly than that produced by SMRs. SMRs do not have a large application in energy production. It has not completely reduced dependency on other renewable sources of energy.
  • Although the SMRs can be shipped to remote locations, problems might arise in the case of infrastructure. There is limited grid coverage in such areas and also the grid connection costs for electrification are high.
  • There are concerns associated with nuclear technologies being proliferated in non-Nuclear Weapon States. It is a violation of the NPT (Non-Proliferation Treaty). If such vital nuclear information reaches such states, there will be a higher chance of nuclear warfare. It will lead to destabilising relations between countries and violation of national sovereignty.

What are Microreactors?

  • Microreactors are smaller versions of nuclear reactors. It produces 10 MW of thermal energy that is used to produce electricity.
  • Akin to Small Modular Reactors, Microreactors reactors have other non-electric and industry applications.
  • Similar to small modular reactors, microreactors can be fully assembled at a factory and transported to locations.
  • Microreactors save time and construction costs. Eventually, these microreactors would be relatively smaller. Thus, they may be shipped easily through trucks, ships or aeroplanes to remote locations, military bases etc.
  • Similar to SMRs, microreactors require passive safety systems to avoid overheating or meltdown of the reactor.

Role of SMRs in a Hybrid Energy System

SMRs alongside other renewable sources of energy like solar power or wind power is cost-effective. This combination of different energy sources is called a hybrid energy system. Such a hybrid application alongside battery storage technology will prove cost worthy. This will solve the issues associated with climate change. SMRs with these cheaper alternatives are one big way to ensure that.

Countries Adopting Small Modular Reactors

  • The first land-based Small Nuclear Reactor, Linglong One was constructed in China. It is a prototype under development and the project is likely to be finished by the end of 2026.
  • Other SMRs under construction are TMSR-LF1 (China), BREST-OD-300 (Russia), CAREM (Argentina) and HTR-PM (China).
  • The first operating prototype of an SMR, Akademik Lomonosov is the only one operating (as of October 2022) in Pevek, Russia.
  • The Small Modular Reactors under licensing stage are MMR (US), BWRX-300 (US), NuScale (US), Rolls-Royce SMR (UK), SMART (South Korea), and VBER-300 (OKBM Afrikantov).
  • In India, 6795 MW(e) of energy is produced through nuclear reactors. Further, 8 units are under construction that would produce up to 6000 MW of electricity. The country is yet to introduce SMRs to meet energy requirements and replace thermal power plants.

Final Thought!

Although the idea of a Small Modular Reactor is old, we are yet to see it bloom in energy generation and other activities. Due to its high cost, countries are slow in their progress towards adopting it. With advancements in science, we may witness SMRs replacing other renewable sources of energy. Although, we might become more reliant on SMRs, we will see a world where energy is produced with zero-carbon emissions. This will help us achieve a world that is environment-friendly.

What are your thoughts on Small Modular Reactors or SMRs? What do you think are the challenging issues that needs to be addressed regarding SMRs? Share with us in the comment section below.


Frequently Asked Questions (FAQs)


What are the disadvantages of small modular reactors?

The disadvantages of small modular reactors are:

  • Not cost-effective
  • Infrastructural issues
  • Limited grid coverage and connection in remote areas
  • Nuclear proliferation concerns etc

Who is making small modular reactors?

The countries investing in small modular reactors are the US, the UK, Canada, China and Russia. Some companies investing in SMRs are Rolls-Royce, NuScale,

How long do small modular nuclear reactors last?

Small nuclear reactors typically require refuelling with a minimum of 3 years in some cases and a maximum of 30 years in others. The lifespan of SMRs is expected to be of 60 years.

What fuel do small modular reactors use?

The fuels used in Small Modular Reactors include Uranium and Plutonium. Thermal-neutron reactors use uranium as fissile material and fast-neutron reactors use plutonium for the same.

What is the safest nuclear reactor?

Liquid fluoride thorium reactors are the safest nuclear reactor in comparison because they are meltdown-proof. In case of power failure or overheating, the fuel will be automatically drained and subsequently stored in an underground tank for future use.

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