Question

Control rods made of cadmium or boron moderate the fission reactions in nuclear power plants. Which of the following best describes how control rods function?

A) Control rods absorb the high heat that is produced from the fission reactions, preventing overheating from occurring.

B) Control rods absorb some of the fast moving neutrons that are produced in the fission reactions, preventing their initiation of other fission reactions.

C) Control rods absorb the steam produced when the water is heated to a high temperature, preventing the generation of electricity.

D) Control rods absorb gamma rays that are responsible for initiating a chain reaction.

E) Control rods act as a catalyst for the reverse of the fission reaction, preventing the fission reaction from continuing.

Answer 1

Control rods in a nuclear reactor are made of materials like cadmium and boron, which absorb fast-moving neutrons to regulate the rate of nuclear fission reactions and prevent overheating or meltdown.

Step-by-step explanation:

The function of control rods in a nuclear reactor is to absorb some of the fast-moving neutrons produced during the fission reactions. Control rods are constructed from materials such as cadmium, boron, or hafnium, which are very good at absorbing neutrons. When these rods are inserted into the reactor core, they capture neutrons, thereby slowing the rate of fission reactions and as a result, decrease the power output of the reactor. If more heat is needed, raising the control rods allows more neutrons to continue the chain reaction, hence increasing energy production. In emergency situations to halt the reaction, the control rods can be fully inserted, absorbing enough neutrons to stop further fission reactions effectively.

To directly answer the student's question, the best description of how control rods function is: B) Control rods absorb some of the fast moving neutrons that are produced in the fission reactions, preventing their initiation of other fission reactions. This helps maintain the nuclear reaction at a stable rate, preventing potential overheating or meltdown.