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.
Key Stats
100/100
CANDU — Canada Deuterium Uranium Reactor
Design Overview
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.
Key Specifications
Typical output: 500–900 MWe. Uses natural uranium or slightly enriched uranium. Heavy water moderator/coolant. Can also use thorium or recycled fuel.
Who Builds It
Atomic Energy of Canada Limited (AECL) / SNC-Lavalin (now AtkinsRéalis)
Where It's Deployed
Canada, India, South Korea, Romania, Argentina, China, Pakistan
Advantages
No uranium enrichment needed. On-line refueling = high capacity factor. Fuel flexibility (natural U, thorium, MOX). Strong neutron economy.
Disadvantages
High capital cost due to heavy water. Heavy water leaks are tritium hazard. Large physical footprint.
Technology reference note · Second Atomic Age Nuclear Wiki Last updated: 2026-05-10
Sources
- IAEA - Heavy Water Reactors [UNVERIFIED] — Overview of heavy water reactor technology, including CANDU design principles.
- World Nuclear Association - Heavy Water Reactors [UNVERIFIED] — Detailed information on CANDU reactors, including design, deployment, and operational characteristics.
- Wikipedia - CANDU Reactor — Comprehensive entry on CANDU technology, history, and global use.
- AtkinsRéalis (formerly SNC-Lavalin) - Nuclear [UNVERIFIED] — Official page of the primary organization involved in CANDU development and support.
Sources (1)
Related Notes
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.
technologiesGen 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.
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.