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Write short note on following: (a) Condenser in Thermal power plant (b) Control of nuclear reactor

      

Write short note on following:
(a) Condenser in Thermal power plant
(b) Control of nuclear reactor

  

Answers

gregory
(a) Condenser in Thermal Power Plant
The steam after expansion through the turbine goes to condenser to improve efficiency of the
power plant by decreasing the exhaust pressure of the steam below atmosphere. Another
advantage of condenser is that condensed steam can be recovered and this provides a source
of good and pure feed water to the boiler. Thereby, reducing considerably the water softening
plant capacity. The air and non condensable gases are removed from the steam, when it
passes through the condenser.
(b) Control of Nuclear reactor:
Once fission process is started in a few nuclei of fission materials, it should be able to
continue throughout the remaining material without external interference. For each act of
fission, nearly 2.5 neutrons capable of causing further fission are proceeded. A self-sustaining
chain reaction is not possible. The leakage of neutron through it is inevitable. Both fission
and non fission reduces the number of neutrons actually available to maintain the chain
reaction.
The reproduction factor (k) is defined as:
k=number of neutrons of any generation devided by the number of neutrons of immediately proceeding generation
k = 1 ; means chain reaction will continue.
k > 1 ; means chain reaction will be building up.
k < 1 ; means chain reaction will be dying down(due critical)
The desirable requirement of power reactor is that the system should be critical i.e
k =1. When we want to control reactor, we have to change the value of k. At the
time of starting the reactor value of k has to be raised above 1. This will increase the power
level.
Once the required power level has been reached, k is to be reduced to 1 and should
be kept at this value as long as the out-put rate is to be kept constant. When the load on the reactor is to be lowered, the k has to be reduced to slightly less than 1 till the required
power level has been reached. At this point k has to be brought back to 1. Similarly, while
shifting down the reactor, the k has to be reduced to less than 1, the chain reaction will die
down.
gregorymasila answered the question on February 22, 2018 at 16:39

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