Small Modular Reactors

A small modular reactor (SMR) is a nuclear fission reactor designed to produce up to 300 MWe per unit, substantially less than a typical large nuclear power reactor. It is modular because major systems can be factory-fabricated, transported to the site and assembled as standardized units, rather than being constructed mainly as a large, site-specific project.

Scale and plant configuration

• Each reactor module has a much smaller electrical output than a conventional large reactor, allowing it to serve smaller grids or specialised electricity and heat requirements.
• A plant may begin with one module and add further modules as demand and finance permit; conventional stations generally commission a few large units.
• SMR is a size and deployment category, not one reactor technology: designs may employ different fuels, coolants and neutron spectra.

Manufacture and deployment

SMRs shift more construction from the project site to controlled factories. Standardized factory fabrication and transportable components are intended to shorten site work, enable repeated production and reduce construction risk.

• Capacity can be added in phases, reducing the capital required for each investment increment compared with a single large unit.
• Their smaller footprint and output can widen siting options, including replacement of retiring fossil-fuel capacity, subject to regulatory and safety requirements.

Safety and economic implications

Many SMR designs employ passive safety systems and simpler arrangements that use natural forces such as gravity or convection. Their lower power and smaller radioactive inventory per module can make decay-heat removal easier, but nuclear safety, security, safeguards and waste management remain necessary.

• Large conventional reactors pursue economies of scale within each unit, whereas SMRs seek economies from standardisation, factory learning and serial production.
• Lower capital per module does not automatically mean cheaper electricity; competitiveness depends on financing, manufacturing volume, operating performance and regulation.