Question

The control rod in a nuclear reactor is made of.
A. Cadmium
B. Uranium
C. Graphite
D. Plutonium

Answer 1

Hint: A nuclear reactor has uranium as reactants and in the reaction chamber uranium undergoes nuclear fission and this reaction is self-sustaining and can spiral out of control. So to control the rate of nuclear fission Control Rods are used that absorb any stray neutrons and control the rate of reaction.

Complete step-by-step answer:
To control the rates of nuclear fission of uranium and plutonium in nuclear reactors, control rods are used. For this purpose, the control rods have to be capable of absorbing neutrons without fissioning themselves. Control rods are made up of cross-section to stop neutrons of various energies. Control Rods are made up of Boron, Cadmium, Silver and Indium to control the rate of nuclear fission.

So, the correct answer is “Option A”.

Additional Information: A nuclear reactor works on the principle of energy generated in the process of controlled nuclear fission. In nuclear reactors that use uranium as the reactant, there is a self-sustaining nuclear reaction that produces 2.5 neutrons per second and those neutrons cause further uranium to undergo fission. The reaction is controlled by controlling the number of neutrons escaping per fission and generally, 1.5 neutrons are allowed to escape to keep the fission controlled.

Note: The control rods made up of Cadmium Boron etc are pushed into the reaction chamber and they absorb the extra neutron and hence provide control over the rate of fission. They are pushed in and out of the reaction chamber that changes the surface area of control rods inside the chamber and the amount of neutrons absorbed by them.