Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos
boiling-water reactor
References
Images
Diagram showing three types of power cycles in nuclear power plants: a single-loop cycle with one closed water circuit from reactor to turbine, a two-loop cycle with separate primary and secondary loops connected by a steam generator, and a three-loop cycle adding a tertiary loop and heat exchanger for extra separation between the reactor and turbine systems. Cutaway diagram of a boiling-water nuclear reactor showing labeled internal components, including steam outlet, core spray inlet, steam separator, fuel assemblies, control rod drive mechanism, and recirculating water system.
Britannica AI Icon

boiling-water reactor

physics
Also known as: BWR
Written by
The Information Architects of Encyclopaedia Britannica

The Information Architects maintain a master list of the topics included in the corpus of  Encyclopædia Britannica, and create and manage the relationships between them.
The Information Architects of Encyclopaedia Britannica
Last updated

Quick Summary

Diagram showing three types of power cycles in nuclear power plants: a single-loop cycle with one closed water circuit from reactor to turbine, a two-loop cycle with separate primary and secondary loops connected by a steam generator, and a three-loop cycle adding a tertiary loop and heat exchanger for extra separation between the reactor and turbine systems.
basic power cycles in nuclear power plants Basic power cycles in nuclear power plants

(A) Single-loop cycle; as shown, it represents a boiling-water reactor (BWR), but it could also represent a direct-cycle, high-temperature gas-cooled reactor (HTGR) if helium were substituted for steam. (B) Two-loop cycle; the primary loop depicted here could constitute a pressurized-water reactor (PWR), a CANDU pressurized heavy-water reactor (PHWR), or a helium HTGR. (C) Three-loop cycle; this is found only in sodium-cooled reactors where an intermediate loop of nonradioactive sodium is provided between the radioactive primary loop and the steam generator.

A boiling-water reactor (BWR) is a type of light-water reactor that uses ordinary water as both a coolant and a moderator. In a BWR, water passes through the reactor core and boils at an intermediate pressure, producing steam. This steam is then purified and used directly to turn a turbine, which drives an electric generator.1

BWRs operate on a direct power cycle, meaning the steam generated in the reactor vessel goes straight to the turbine. This design is more compact than pressurized-water reactors (PWRs) because it doesn't require separate steam generators. However, BWRs operate at lower pressures and temperatures than PWRs, resulting in slightly lower thermodynamic efficiency. The reactor vessel in a BWR is larger in diameter for the same power output compared to a PWR due to its lower power density. Safety systems, such as control rods, are crucial for managing the chain reaction and preventing accidents.234

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
6 Britannica Sources
  1. nuclear reactor - PWRs and BWRs
  2. nuclear reactor - Systems and structures
  3. nuclear reactor - Advantages and disadvantages
  4. nuclear reactor - Heat removal
  5. nuclear reactor - Reactor control elements
  6. nuclear fission - Uses of fission reactors and fission products

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.