This reactor uses two liquid metal coolants. Liquid sodium (Na) as the primary coolant and an alloy of sodium potassium (NaK) as the secondary coolant.
Sodium melts at 208°C and boils at 885°C. This will help to achieve high outlet coolant temperature in the reactor at moderate pressure nearly atmospheric which can be utilized in producing steam of high temperature, thereby increasing the efficiency of the plant.
Steam at temperature as high as 540○C has been obtained by this system. By using liquid sodium as coolant more electrical power can be generated for a given quantity of the fuel burn up.
Secondly low pressure in the primary and secondary coolant circuits permits the use of less expensive pressure vessel and pipes etc.
Further sodium will transfer its heat very easily. The only disadvantage is that sodium becomes radioactive whereas passing through the core and reacts chemically with water.
So it’s not used directly to transfer its heat to the feed water however a secondary coolant is used. Intermediate heat exchanges (I.H.X) transfers the primary coolant’s heat to the secondary coolant through the tubes.
After that secondary coolant flows via the tubes of steam generator and passes on its heat to the feed water.
Graphite is used as a heat transfer media that have some advantages.
The various advantages of using liquid metals as heat transfer media are relatively low melting points and combine high densities with low vapor pressure at high temperatures as well as with large thermal conductivities.
Safety measures followed in nuclear power plant :
Safety for nuclear power plants: Nuclear power plants should be located far away from the populated area to avoid the quanta which g particles, neutrons and b and a radioactive hazard.
A nuclear reactor produces can disturb the normal functioning of living organisms. Nuclear power plants involve radiation leaks, health hazard to employees and community and negative effect on surrounding forests.
The sources of radioactive contamination of air in nuclear power plant are
Fission of nuclei of nuclear fuels.
carrier in the primary cooling system and on the ambient air because of the effect of neutron fluxes on the heat.
Damage of shells of fuel elements.
Construction quality is needed in standard level.
The waste water which was came out from nuclear power plant will be purified. The water purification plants must have efficiency of water purification and satisfy rigid requirements as regards the volume of radioactive wastes disposed to burial.
An atomic power plant have an extensive ventilation system. The purpose of this system is to maintain the concentration of all radioactive impurities in the air below the permissible concentrations.
Nuclear power plant should be situated away from human habitation.
The safety system of the plant should be such as to enable safe shut down of the reactor whenever required. Nuclear Power plants generate large quantities of highly radioactive material.
This is due to the left over isotopes (atoms) from the splitting of the atom and the creation of heavier atoms, like plutonium, which the Nuclear Power plant does not utilize. It is called nuclear waste.
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