lämpöneutronaaleilla

Lämpöneutronaaleilla is a Finnish term referring to thermal neutrons. Thermal neutrons are neutrons that have been slowed down to kinetic energies that are comparable to the thermal energies of surrounding atoms or molecules. This typically occurs when neutrons interact with matter through scattering, losing energy in each collision. The energy of a thermal neutron at room temperature is approximately 0.025 electronvolts.

These low-energy neutrons play a crucial role in nuclear reactor physics, particularly in sustaining nuclear fission chain reactions. In many nuclear reactor designs, a moderator material such as water or graphite is used to slow down fast neutrons produced by fission to thermal energies. These thermal neutrons are then much more likely to be captured by fissile isotopes, such as Uranium-235, leading to further fission events and thus sustaining the chain reaction.

The cross-section for neutron capture and scattering interactions is highly dependent on the neutron's energy. For many nuclear materials, the probability of interaction, especially fission, is significantly higher for thermal neutrons compared to fast neutrons. This principle is fundamental to the operation of most nuclear power reactors and some research reactors. The study and control of thermal neutron behavior are essential for reactor design, safety, and efficiency.