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Chapter 38: Problem 9

Explain and distinguish the roles of the control rods and moderator in a nuclear reactor.

Short Answer

Expert verified
Control rods and moderators are integral parts of a nuclear reactor with distinct roles. Control rods absorb neutrons, controlling the rate of the nuclear reaction. Moderators slow down the fast neutrons produced by fission, thereby increasing the likelihood of further fission events and helping to maintain a sustained chain reaction. Though both are crucial for the operation and safety of a nuclear reactor, they perform different tasks.

Step by step solution

01

Explaining Role of Control Rods

Control rods are crucial components of a nuclear reactor. They are made from materials that absorb neutrons, such as cadmium, hafnium, or boron. The primary role of control rods is to control the rate of the nuclear chain reaction. By adjusting the position of control rods within the reactor core, we can increase or decrease the number of neutrons which interact with the uranium fuel, thereby regulating the rate of fission events and the production of thermal energy.
02

Explaining Role of Moderator

A moderator is a component of a nuclear reactor that slows down the fast neutrons produced by fission. Moderators can be made of water, heavy water, or graphite. The role of the moderator is crucial in achieving and maintaining a sustained chain reaction. Fast neutrons are less likely to cause further uranium fission, so they must be slowed down to thermal speeds by the moderator. This process increases the efficiency of the nuclear chain reaction.
03

Distinguishing Between Control Rods and Moderator

While both control rods and moderators play important roles in maintaining a nuclear reaction, they perform distinctly different tasks. Control rods are primarily responsible for controlling the rate of the nuclear reaction. They do this by absorbing excess neutrons, thereby preventing them from causing more fission events. On the other hand, the moderator's main purpose is to slow down the neutrons so they are more likely to interact with the uranium fuel and sustain the chain reaction. Both parts work together to ensure the nuclear reactor operates safely and efficiently.

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