Explain the role of control rods in a reactor. Why are they made of cadmium ?

Explanation

### Step-by-Step Solution:

1. **Understanding Control Rods**: Control rods are essential components in a nuclear reactor. Their primary function is to manage the rate of the nuclear fission reaction.

2. **Function of Control Rods**: In a nuclear reactor, when uranium isotopes undergo fission, they release neutrons. These neutrons can cause further fission reactions, leading to a chain reaction. Control rods are inserted into the reactor core to absorb some of these free neutrons, thereby controlling the number of neutrons available to sustain the chain reaction.

3. **Controlling the Chain Reaction**: By adjusting the position of the control rods (inserting them deeper into the reactor or withdrawing them), operators can increase or decrease the rate of the fission reaction. If more control rods are inserted, more neutrons are absorbed, and the reaction slows down. Conversely, if control rods are withdrawn, fewer neutrons are absorbed, and the reaction speeds up.

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