Question

A self-sustaining nuclear process, in which the bombarding particles needed to produce the fission of further material are themselves produced as the product of the initial fission, is called a __________ reaction.

Short answer

A self-sustaining nuclear process, in which the bombarding particles needed to produce the fission of further material are themselves produced as the product of the initial fission, is called a \(\textbf{chain reaction}\).

Step-by-step solution

Identify the term for self-sustaining nuclear process

The type of nuclear reaction described in the exercise, where the bombarding particles cause more fission and are also produced from that same fission process, is known as a "chain reaction". So, the answer is: Chain Reaction.

Key concepts

Nuclear Fission

Nuclear fission is a process where the nucleus of an atom splits into two or more smaller nuclei, along with a few neutrons and a large amount of energy. This phenomenon is essential in the realm of nuclear physics and has both peaceful and military applications.

The most common fission process involves a heavy element, such as uranium-235, which is unstable. When this nucleus captures a neutron, it becomes even more unstable and divides into two new atoms, releasing energy as well as additional neutrons. These newly released neutrons can then initiate fission in other nuclei, leading to a series of reactions.

Understanding the Basics of Nuclear Fission

When an atom undergoes fission, the total mass of the resulting fragments is less than the original mass. This lost mass is converted into energy according to Einstein's famous equation, \(E=mc^2\), where \(E\) is energy, \(m\) is mass, and \(c\) is the speed of light. This energy is what makes nuclear fission a powerful source for electricity generation in nuclear power plants and also the destructive force behind nuclear weapons.

Self-Sustaining Nuclear Process

A self-sustaining nuclear process is a reaction where once initiated, it continues to occur without the need for additional energy or input from outside sources. In the context of nuclear fission, this concept is best illustrated by the chain reaction.

In a controlled environment, such as a nuclear reactor, the chain reaction is managed to ensure a stable release of energy for power generation. Nuclear reactors are designed with mechanisms to control the rate of fission, such as control rods that absorb excess neutrons, preventing the process from accelerating uncontrollably.

Control and Safety in Self-Sustaining Nuclear Processes

Control rods, coolant systems, and containment structures are critical for maintaining safety in nuclear power plants. These safety systems prevent the reaction from becoming too energetic, which could lead to overheating and potential meltdown. The key to a self-sustaining nuclear process is balance: sufficient neutron production to maintain the reaction, but not so much that it leads to a runaway scenario.

Bombarding Particles

Bombarding particles are high-energy particles that initiate nuclear reactions such as fission by colliding with atomic nuclei. In a nuclear chain reaction, these particles are typically free neutrons that have been ejected from previous nuclear reactions.

When a neutron collides with the nucleus of a fissile isotope, like uranium-235, it can be absorbed and cause the nucleus to become unstable, leading to fission. The importance of neutrons lies in their lack of electric charge, which allows them to penetrate the nucleus without being repelled by the positive charge of protons.

The Role of Neutrons in Nuclear Fission

Neutrons play a crucial role in sustaining a chain reaction. Their energy and number determine if the reaction will die out, remain steady, or grow exponentially. In nuclear weapons, the goal is a rapid, uncontrolled chain reaction, whereas, in a nuclear reactor, the process is precisely regulated to ensure safety and to harness the energy for producing power.