Technologies
BWR — Boiling Water Reactor
Water boils directly in the reactor vessel, producing steam that drives turbines directly. Simpler single-loop design than PWR but the steam is mildly radioactive, requiring turbine building shielding.
CANDU — 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.
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.
Gen IV MSR — Generation IV Molten Salt Reactor
Fuel dissolved in molten fluoride or chloride salt that serves as both fuel and coolant. Operates at atmospheric pressure. Potential for thorium fuel cycle. Strong load-following. Several startups pursuing designs; none at commercial scale yet.
Gen 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.
PWR — 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.
RBMK — 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.
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.
VVER — 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.