Neutron poison

Neutron Poison

Schematic of control rods in a nuclear reactor.

A neutron poison is a substance with a large neutron absorption cross-section, in nuclear physics and nuclear engineering. Neutron poisons are used to control the reactivity of a nuclear reactor by absorbing excess neutrons, thereby reducing the number of neutrons available to sustain the nuclear chain reaction.

Types of Neutron Poisons

Neutron poisons can be classified into two main categories: burnable poisons and non-burnable poisons.

Burnable Poisons

Burnable poisons are materials that absorb neutrons and are gradually converted into non-poisonous isotopes. This conversion allows for a more stable and prolonged control of reactivity over the fuel cycle. Common burnable poisons include boron-10 and gadolinium.

Non-Burnable Poisons

Non-burnable poisons, also known as fixed poisons, do not change significantly over the course of the reactor operation. They are used for long-term reactivity control and include materials such as hafnium and cadmium.

Role in Nuclear Reactors

Neutron poisons play a crucial role in the safe and efficient operation of nuclear reactors. They are often incorporated into control rods, which can be inserted or withdrawn from the reactor core to adjust the reactivity. Control rods are typically made from materials like silver, indium, and cadmium, which are effective neutron absorbers.

Control Rods

Illustration of control rods in a reactor core.

Control rods are an essential component of a nuclear reactor's safety system. They are designed to absorb neutrons and regulate the fission process. By adjusting the position of the control rods, operators can control the reactor's power output and maintain a stable and safe operating condition.

Related Pages

• Nuclear reactor
• Nuclear fission
• Neutron absorption
• Control rod
• Burnable poison