Which of the following materials is used to control the power of a nuclear reactor?

The correct answer is Boron.

Key Points

• Boron is widely used as a neutron absorber in nuclear reactors to control the rate of the fission reaction.
• It is primarily used in the form of boron carbide (B₄C) or boric acid in control rods and reactor coolant systems.
• Boron absorbs excess neutrons, helping to regulate the chain reaction and prevent the reactor from overheating or going out of control.
• Its high neutron absorption cross-section makes it an effective material for maintaining nuclear reactor stability.
• Boron compounds are also used in emergency shutdown systems to quickly halt the nuclear fission process when needed.

Additional Information

• Control Rods: Control rods are devices made of materials like boron, cadmium, or hafnium that absorb neutrons to regulate the nuclear chain reaction.
• Neutron Moderators: Substances like graphite and heavy water are used to slow down neutrons to sustain the chain reaction, but they do not control its intensity directly.
• Chain Reaction: A nuclear chain reaction occurs when neutrons produced during fission cause further fissions, releasing energy in a controlled or uncontrolled manner.
• Neutron Absorption Cross-Section: This refers to the likelihood of a material, such as boron, to absorb neutrons. Boron has a high absorption cross-section, making it ideal for nuclear reactor control.
• Types of Nuclear Reactors: Common reactor types include Pressurized Water Reactors (PWRs) and Boiling Water Reactors (BWRs), both of which use boron-based systems for safety and control.