250+ TOP MCQs on Nuclear Reactor Main Parts and their Functions and Answers

Power Systems Multiple Choice Questions on “Nuclear Reactor Main Parts and their Functions”.

1. In which part of nuclear power plant steam is produced?
A. Boiler
B. Heat exchanger
C. Chamber across the reactor
D. Air preheater
Answer: B
Clarification: There is no boiler in nuclear power plant. The heat energy released in the reactor during nuclear fission is utilised to heat the coolant. This coolant is circulated through the heat exchanger to produce steam.

2. What is the main function of moderator?
A. It absorb the extra neutrons
B. It divert extra neutrons
C. It slow down the speed of fast neutrons
D. It absorb the heat energy caused by nuclear reaction
Answer: d
Clarification: Neutrons rejected during the fission process at a very high velocity of about 1.5 × 107 m/s. For more effective use in nuclear reactor it is desirable to slow down the fast neutrons to speed corresponding to the speed of molecules of gas at normal temperature and pressure. This is accomplished with the help of moderator.

3. Which of the following material is not used as moderator?
A. Oxygen
B. Ordinary water
C. Heavy water
D. Graphite
Answer: A
Clarification: At present the common moderator materials used are graphite, ordinary water and heavy water. Oxygen is not suitable to use due to its low density and the consequent small number of collision.

4. Which of the following part of nuclear reactor is used to control the rate of reaction.
A. Moderator
B. Control rods
C. Reflector
D. Coolant
Answer: B
Clarification: In a reactor the chain reaction is to be maintained at steady value during the operation of reactor. Also the reactor must be able to shutdown automatically under emergency conditions. All these requires control rods for control of reactor so as to prevent the melting of fuel rods, disintegration of coolant and destruction of reactor as the amount of energy released is enormous.

5. Which of the following is the most essential requirement of control rod material?
A. It must be light weight
B. It must be cheap
C. It must have high absorption capacity for neutrons
D. It must be very reflective to neutrons
Answer: C
Clarification: The function of control rod is to control the rate of nuclear reaction by absorption extra release neutrons. Chain reaction is controlled either by removing or inserting neutron absorbing materials. The materials used for control rods must have very high absorption capacity for entrance.

6. Which of the following can be used as both as coolant and moderator ?
A. Helium
B. Molten sodium
C. Lithium
D. Ordinary water
Answer: D
Clarification: A good coolant should not absorb neutrons, should be non-oxidizing, non-toxic, non corrosive, should have high chemical and radiation stability and good heat transfer ability. Ordinary water is used as both as coolant and moderator in boiling water reactor and pressurized water is used as both as coolant and moderator in pressurized water reactor.

7. In thermal reactors control is very easy in comparison to other reactors.
A. True
B. False
Answer: A
Clarification: In thermal reactor control his very easy because of relatively low power densities and longer in neutron lifetime.

8. The main body of reactor is called ____________
A. Thermal shielding
B. Reactor vessel
C. Reflector
D. Biological shielding
Answer: B
Clarification: The reactor core, reflector and thermal shielding are all enclosed in the main body of reactor and is called reactor vessel or tank. It is strong walled container and provides the entrance and exit for the coolant. It also provides the passage for flow of coolant through and around the reactor core.

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