What Are Source Neutrons?

Particles

• Neutrons are elementary particles of matter that scientists use in a variety of modern technologies. Through complicated calculations, scientists create beams of neutrons. Scientists aim a beam of neutrons at an atom and nuclear fission occurs. The neutrons bombard the atom until it splits into two, releasing energy that becomes electricity. Source neutrons are always present within a neutron induced fission reactor.

Source Neutrons

• "Source neutrons" is a term that refers to all the neutrons present in a reactor core that are not the result of the neutron-induced fission. These neutrons are present whether the reactor is in operation or not and during shutdown and startup. Some source neutrons come from natural reactions going on inside the core. These are called intrinsic source neutrons. Others come from fabricated sources and are called installed source neutrons.

Neutron Sources

• Intrinsic neutron sources are unavoidable reactions that will always occur during the fission process. They are random events of neutron-producing reactions that occur between materials in the core. These events do not include the neutrons produced by fission. However, scientists add installed sources because intrinsic sources can be weak. Installed sources are elements such as beryllium and nuclide californium-252. The addition of these elements to the reaction produces source neutrons.

Uses

• Scientists add installed source neutrons to a reactor to keep the source neutron level high. Neutrons must always be present in a reactor core whether it is in operation, starting up or shutting down. Because these particles are so small, there must be a lot of them in order for the most sensitive instruments to pick them up. The instruments are the only way that scientists can see what is happening inside the reactor, so source neutron levels are kept high in order to allow them to measure what is going on.