Definition

1. Noun:
   • A neutron-absorbing rod used to regulate a nuclear reactor: A "control rod" is a device, typically a rod made of materials like boron, cadmium, or hafnium, that absorbs neutrons. It is inserted into or withdrawn from the core of a nuclear reactor to control the rate of the fission chain reaction, thereby controlling the reactor's power output.

Usage Examples

• Noun:
  • The operators lowered the control rods to shut down the nuclear reactor safely.
  • A key safety feature is the ability to insert all control rods rapidly in an emergency.
  • The position of the control rod determines how many neutrons are available to sustain the fission process.

Advanced Usage

• "Rod drop" or "scram": The rapid, full insertion of all control rods to immediately terminate the nuclear chain reaction.
  • The automatic safety system initiated a scram, driving all control rods into the core.

Variants and Related Words

• Control rod drive (CRD): The mechanism that moves the control rod into or out of the reactor core.
• Shim rod: A type of control rod used for coarse adjustment of reactor reactivity.
• Regulating rod: A type of control rod used for fine, precise adjustment of reactor power.

Synonyms

• Neutron absorber: Describes the primary function of the material in a control rod.
• Reactivity control device: A more general technical term for equipment that manages the nuclear reaction rate.

Related Phrases

• To insert the control rods: To move the rods further into the reactor core to decrease power.
• To withdraw the control rods: To move the rods out of the reactor core to increase power.
• Rod worth: A measure of a control rod's effectiveness in changing the reactor's reactivity.

Noun

1. a steel or aluminum rod that can be moved up or down to control the rate of the nuclear reaction