How does a fast moving neutron make fission of U 235 happen?

When a free neutron hits the nucleus of a fissile atom like uranium-235 (235U), the uranium splits into two smaller atoms called fission fragments, plus more neutrons. Fission can be self-sustaining because it produces more neutrons with the speed required to cause new fissions. This creates the chain reaction.

How does a fast neutron reactor work?

A fast-neutron reactor (FNR) or fast-spectrum reactor or simply a fast reactor is a category of nuclear reactor in which the fission chain reaction is sustained by fast neutrons (carrying energies above 1 MeV or greater, on average), as opposed to thermal neutrons used in thermal-neutron reactors.

Why slow neutrons are more effective for fission?

It is just because the fissile Uranium 235 nuclei have a higher cross-section, i.e., a much higher probability, to absorb slow neutrons than fast neutrons. Majority of the currently operating nuclear power reactors in the world are based on thermal or slow energy neutrons.

Can uranium 238 undergo fission?

Uranium-238 and thorium-232 (and some other fissionable materials) cannot maintain a self-sustaining fission explosion, but these isotopes can be made to fission by an externally maintained supply of fast neutrons from fission or fusion reactions.

Can fast neutrons cause fission?

Neutrons produced by fission have high energies and move extremely quickly. These so-called fast neutrons do not cause fission as efficiently as slower-moving ones so they are slowed down in most reactors by the process of moderation.

Can u-238 undergo fission?

What are the fission products of uranium-238?

Bombarding enriched uranium fuel (Uranium-235: 3-5\%; Uranium-238: 95-97\%) with neutrons results in nuclear fission. Radioactive nuclear fission products such as Iodine-131, Cesium-137, and Strontium-90 are created in this process. When Uranium-238 is bombarded with neutrons, Plutonium-239 is created.