Sodium Graphite Reactor (SGR) Power Plant

What is Sodium Graphite Reactor?

The sodium graphite reactor is a typical liquid metal reactor. The arrangement of the sodium graphite reactor power plant is shown in the figure.

Sodium Graphite Reactor Power Plant |
Sodium Graphite Reactor Power Plant

It uses graphite as a moderator and liquid sodium as a coolant which reaches a temperature of about 850 degrees Celsius at a low pressure of only 7 bar.

In the primary circuit, the heat is absorbed by liquid sodium in reactor. The sodium becomes radioactive while it passes through the core and reacts chemically with water.

Therefore, the heat absorbed by sodium is transferred to secondary coolant sodium-potassium (NaK) in the primary heat exchanger which in turn transfers the heat in the secondary heat exchanger called a Steam generator.

Water leaving the generator is converted into superheated steam up to a temperature of 540 degrees Celsius. This steam is used for power generation in the steam plant circuit in the usual manner. The reactor vessel, primary circuit, and primary heat exchanger have to be shielded from radiations.

The liquid metal is required to be handled under the cover of an inert gas like helium to prevent contact with air while charging or draining in the primary and secondary heat exchangers.
See Also: Types of Nuclear Reactors

Advantages of Sodium Graphite Reactor (SGR)

1. The high temperature of the steam can be obtained due to the use of liquid sodium as a coolant.
2. Thermal efficiency is high.
3. The system need not be pressurized.
4. The cost of the pressure vessel and piping system is reduced due to the use of low-pressure sodium in the primary circuit.

Disadvantages of Sodium Graphite Reactor

1. Any leakage of sodium coolant is highly dangerous.
2. Sodium is highly violent with air and water.
3. Primary and secondary heat exchangers are needed to be shielded with concrete blocks against radiations.
4. An intermediate heat exchanger is required to separate radioactive sodium with water and steam.

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