SMR — Small Modular Reactor
Factory-fabricated reactors typically under 300 MWe designed for modular deployment. Various designs span PWR, BWR, molten salt, high-temperature gas, and fast neutron variants. Most are in licensing or early construction phases as of 2025.
Key Stats
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SMR — Small Modular Reactor
Design Overview
Factory-fabricated reactors typically under 300 MWe designed for modular deployment. Various designs span PWR, BWR, molten salt, high-temperature gas, and fast neutron variants. Most are in licensing or early construction phases as of 2025.
Key Specifications
Typically <300 MWe per module. Factory-built for quality control and cost reduction. Many target passive safety (no active cooling required for 72+ hours).
Who Builds It
NuScale (VOYGR), Rolls-Royce SMR, GE-Hitachi (BWRX-300), TerraPower (Natrium), X-energy (Xe-100), Kairos Power (KP-FHR), Last Energy, many others
Where It's Deployed
First commercial SMRs expected late 2020s. NuScale VOYGR licensed by NRC. Romania/Poland/Canada leading deployment pipelines.
Advantages
Lower upfront capital. Factory manufacturing reduces cost and schedule risk. Flexible siting. Can serve remote or industrial loads. Some designs use advanced fuels.
Disadvantages
Economies of scale disadvantage vs large plants. Many designs not yet proven at commercial scale. Supply chain for novel fuel forms (TRISO, etc.) immature.
Technology reference note · Second Atomic Age Nuclear Wiki Last updated: 2026-05-10
Sources
- IAEA - Small Modular Reactors — Overview of SMR technology and international developments.
- World Nuclear Association - Small Nuclear Power Reactors — Detailed information on SMR designs, vendors, and deployment status.
- Wikipedia - Small Modular Reactor — General encyclopedia entry on SMR technology and history.
- NuScale Power — Official site of NuScale, a leading SMR developer with NRC-licensed VOYGR design.
Sources (1)
Related Notes
Gen IV HTGR — Generation IV High-Temperature Gas-Cooled Reactor
Uses helium as coolant and graphite as moderator. Operates at very high temperatures (750–950°C outlet), enabling industrial process heat, hydrogen production, and high thermodynamic efficiency. TRISO fuel particles provide inherent safety — fuel cannot melt.
technologiesPWR — Pressurized Water Reactor
The most widely deployed reactor type globally. Water is kept under high pressure (~155 bar) to prevent boiling in the primary circuit, then transfers heat via steam generators to a secondary loop that drives turbines. Light water serves as both coolant and moderator.
technologiesCANDU — Canada Deuterium Uranium Reactor
Uses heavy water (D₂O) as both moderator and coolant under pressure. Unique ability to use natural uranium fuel (no enrichment needed). Can be refueled on-line without shutdown.
technologiesGen IV SFR — Generation IV Sodium-Cooled Fast Reactor
Uses liquid sodium coolant (no moderator) enabling fast neutron spectrum. Can breed plutonium from U-238 (breeder reactor) or burn actinide waste. Sodium coolant enables high operating temperatures at low pressure.
technologiesRBMK — Reactor Bolshoy Moshchnosti Kanalnyy (High-Power Channel-Type Reactor)
Soviet-era graphite-moderated, light-water-cooled channel reactor. No containment vessel. Positive void coefficient at low power created dangerous instability — root cause of the Chernobyl disaster. All remaining units are in Russia.
technologiesVVER — Vodo-Vodyanoy Energetichesky Reaktor (Water-Water Power Reactor)
Russian pressurized water reactor design, analogous to Western PWRs but with distinct engineering choices: hexagonal fuel assemblies, horizontal steam generators, and no liner in the pressure vessel. Modern VVER-1200 (Gen III+) features passive safety systems.