NEUTRON MODERATOR Meaning and
Definition
-
A neutron moderator is a material used in nuclear reactors to slow down fast-moving neutrons by means of elastic collisions. These fast-moving neutrons, which are released during nuclear fission, need to be slowed down in order to efficiently sustain the chain reaction in a nuclear reactor. The goal of a neutron moderator is to maximize the probability of neutron absorption by the fissionable material within the reactor, enhancing the process of nuclear fission.
The process of moderation occurs when fast neutrons collide with the nuclei of atoms present in the moderator material, such as graphite or heavy water. These collisions transfer energy from the fast neutrons to the atomic nuclei, effectively reducing their speed and kinetic energy. By slowing down the neutrons, they become more easily captured by the atomic nuclei of the reactor fuel, which promotes further fission and the release of additional neutrons.
The choice of neutron moderator is crucial in reactor design, as it greatly affects the efficiency and safety of the nuclear reaction. The material must strike a balance between slowing down neutrons without excessively absorbing them, as absorption can disrupt the chain reaction. Additionally, the moderator must possess suitable thermal properties to withstand the intense heat generated by the nuclear reactions.
In summary, a neutron moderator is a substance within a nuclear reactor that slows down fast neutrons through elastic collisions, enhancing the efficiency and sustainability of nuclear fission.
Etymology of NEUTRON MODERATOR
The word "neutron moderator" is derived from two different etymological sources.
1. Neutron: The term "neutron" was coined by Ernest Rutherford in 1921 from the Latin word "neutro" (meaning "I make neutral"). Rutherford used this term to describe the electrically neutral subatomic particle that was discovered by James Chadwick in the same year.
2. Moderator: The term "moderator" has its origins in medieval Latin. It comes from the Latin word "moderātor", meaning "one who moderates or controls". In the context of nuclear physics, a moderator is a substance that slows down fast neutrons in order to make them more easily captured by atomic nuclei, thus facilitating a controlled nuclear chain reaction.
