Question

Control rods used in nuclear reactors are made of

• A. stainless steel
• B. graphite
• C. cadmium
• D. plutonium

Answer 1

The correct option is C

cadmium

Explanation for correct option:

1. A control rod is used in the nuclear reactor to control the rate of the nuclear reaction taking place.
2. It is inserted to decrease the rate of fission reaction and it can be taken out to increase the rate of the fission reaction.
3. The control rod element can absorb slow-moving neutrons and does not start a fission reaction or become a radioactive element.
4. Cadmium can absorb slow-moving neutrons efficiently.

Explanation for incorrect option:

Option(a):

1. Stainless steel is used in a nuclear reactor as a radiation shield. It can shield gamma rays and fast neutron radiation produced in a nuclear reactor.

Option(b):

1. Graphite is used as a moderator in the nuclear reactor. A moderator can change a fast-moving neutron into a slow-moving neutron.

Option(d):

1. Plutonium is a radioactive element. It can capture the neutron. But this will result in a nuclear fission reaction.

Hence, the correct option is (C)