The working fluid used in an MHD system coupled to a fast breeder reactor is

MHD generator is a device used for converting heat energy of fuel directly into electrical energy without conventional electric generator.

MHD system works on principle of Faradays laws of electromagnetic induction.

Closed system MHD systems are classified in 2 types:

Seeded Inert Gas Closed-Cycle MHD System:

• This MHD system works on Brayton cycle with inert carrier gas (Argon/helium).In seeded inert gas system, electrical conductivity is maintained in the working fluid by ionization of a seed material.
• The inert gas is compressed and heated in primary heat exchanger.

Small quantity of seed material (e.g., cesium) is them added to make up for the loss of seed through leakage etc. At lower temperature, low cost seed material can also be a used but at low temperature, efficiency of the system reduces.

Close-Cycle Liquid Metal MHD System:

• In this system, a liquid metal (Potassium) is used as a working fluid.
• The liquid potassium after being heated in the ‘breeder reactor’ is passed through the ‘nozzle’ where its velocity is increased.
• The vapours formed due to nozzle action are separated in the ‘separated and condensed and them pumped back to the reactor.
• Then the liquid metal with high velocity is passed through ‘MHD generator’ to produce D.C. power.

The liquid potassium coming out of MHD generator is passed through the heat exchanger’ (boiler) to use its remaining heat to run a turbine-generator set and then pumped back to the reactor.