Types of Reactors and Their Functions | New Topic [2024]

In this note, we are going to learn about different Types of Reactors and Their Functions which are used in Nuclear Power Plants. Welcome to Poly Notes Hub, a leading destination for engineering notes for diploma and degree engineering students.

Author Name: Arun Paul.

Types of Reactors and Their Functions

Nuclear reactors are classified by architecture, fuel type, coolant, and moderator. Listed below are the major types –

1. Light Water Reactors (LWR)

These reactors employ regular water (light water) as both a coolant and a moderator. These reactors are classified into two categories –

• Pressurized Water Reactor (PWR): In this type of reactors, water is kept under high pressure to prevent it from boiling. The heated water transfers its heat to a secondary water circuit, producing steam to drive the turbine.
  • Example: Many reactors in the US and Europe, including ones designed by Westinghouse and Areva.
• Boiling Water Reactor (BWR): In this type of reactor, water boils inside the reactor core, and the produced steam is directly used to drive the turbine.
  • Example: Common in the United States and Japan, including ones designed by GE Hitachi.

2. Heavy Water Reactors (HWR)

These reactors employ heavy water (D2O) as a moderator, allowing them to burn natural uranium as fuel. Below we have listed a reactor like this type –

• CANDU (CANada Deuterium Uranium) Reactor: In this reactor, heavy water acts as both the coolant and the moderator, allowing the use of non-enriched uranium.
  • Example: It is used in Canada and India.

3. Gas Cooled Reactors (GCR)

In this type of reactors gas used as a coolant and graphite as a moderator. These types of reactors are also classified into two categories –

• Advanced Gas cooled Reactor (AGR): It uses CO2 as a coolant to transfer heat from the core to the steam generator.
  • Example: Used in UK.
• High Temperature Gas cooled Reactor (HTGR): It is capable of operating at very high temperatures, which can improve thermal efficiency.
  • Example: Used in China and Japan.

4. Fast Neutron Reactors (FNR)

These reactors use fast neutrons to maintain the fission chain reaction and are intended to produce more fissile material than they consume.

• Fast Breeder Reactor (FBR): It uses fast neutrons to convert fertile material (like U-238) into fissile material (like Pu-239).
  • Example: BN-600 reactor in Russia, Prototype Fast Breeder Reactor (PFBR) in India.
• Liquid Metal Fast Breeder Reactor (LMFBR): It is uses liquid metals to transfer heat and enables efficient breeding of fissile materials.
  • Example: Superphénix in France.

5. Molten Salt Reactors (MSR)

This type of reactors use molten salt as both fuel and coolant. Fuel is dissolved in molten salt, which serves as both a cooling and a medium for nuclear reactions.

• Example: Used as experimental reactors such as the Molten-Salt Reactor Experiment (MSRE) in the United States.

6. Pressurized Heavy Water Reactor (PHWR)

It is similar to LWR but uses heavy water as both the coolant and moderator. Heavy water allows the reactor to use natural uranium and improves neutron economy.

• Example: Used in Canada and in India as well.

7. Breeder Reactors

It is designed to create more fissile material than they consume. It is design to convert fertile materials (U-238 or Th-232) into fissile materials (Pu-239 or U-233).

• Example: Experimental Breeder Reactor II (EBR-II) in the United States, Monju in Japan.