Explainer: How does a small nuclear reactor work?

Small modular reactors (SMRs) are advanced nuclear reactors with approximately one-third the processing power of traditional plants, designed for factory assembly and transport to site. They offer potential advantages in construction cost, speed, and safety through passive systems, with a global market projected to reach $300 billion by 2040. While seen as a low-carbon alternative to fossil fuels, critics argue that investment should instead be directed toward renewables and energy efficiency.

• Small modular reactors (SMRs) differ from conventional nuclear plants because their components can be manufactured in factories and then transported to the site, which may reduce construction risks, costs, and time. For example, Rolls-Royce reports that approximately 90% of its SMR work is conducted in factories, minimizing on-site disruption and allowing for more flexible location choices.
• SMRs utilize nuclear fission to generate electricity and are characterized by a smaller scale; the International Atomic Energy Agency (IAEA) defines 'small' reactors as those under 300MWe. They feature passive safety systems that allow for system shutdowns without active human or external intervention, and they require less fuel than traditional plants.
• The drive toward nuclear technology is fueled by the need for clean energy to reach net-zero emissions and the impact of Russia's invasion of Ukraine on energy prices, particularly in Europe, the UK, and Germany. In terms of greenhouse gas emissions per unit of power, the UK’s Nuclear Advanced Manufacturing Research Centre considers nuclear energy as clean as offshore wind.
• While there are 438 commercial nuclear reactors globally and 56 under construction, SMRs are largely in the development stage, with four of approximately 50 global concepts in advanced construction. The global SMR market is projected to be worth up to $300 billion by 2040.

APA

Nugent, H. (2022). Explainer: How does a small nuclear reactor work? World Economic Forum. https://www.weforum.org/stories/energy-transition/small-nuclear-reactor-modular/

Chicago

Nugent, Helen. Explainer: How does a small nuclear reactor work? World Economic Forum, 2022. https://www.weforum.org/stories/energy-transition/small-nuclear-reactor-modular/.

Wikipedia

{{cite report |last1=Nugent |first1=Helen |title=Explainer: How does a small nuclear reactor work? |publisher=World Economic Forum |date=18 August 2022 |url=https://www.weforum.org/stories/energy-transition/small-nuclear-reactor-modular/ |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{nugent2022explainer, author = {Nugent, Helen}, title = {{Explainer: How does a small nuclear reactor work?}}, institution = {World Economic Forum}, year = {2022}, month = aug, url = {https://www.weforum.org/stories/energy-transition/small-nuclear-reactor-modular/}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }