Monigruppidiffuusiossa

Monigruppidiffuusiossa, also known as "multi-group diffusion" in English, is a term used in the field of nuclear reactor physics. It refers to a computational method for solving the neutron transport equation, which describes how neutrons propagate through a nuclear reactor core.

The multi-group diffusion approximation simplifies the neutron transport equation by dividing neutrons into a finite number of energy groups. Instead of tracking the behavior of individual neutrons across the entire energy spectrum, the method treats all neutrons within a specific energy range as a single group. This simplification significantly reduces the computational complexity compared to more detailed methods like few-group or continuous energy transport calculations.

Each energy group is characterized by its own set of diffusion coefficients, absorption cross-sections, and scattering cross-sections. The interactions between neutrons in different energy groups, such as scattering from a higher energy group to a lower one, are accounted for by coupling terms in the diffusion equations. This allows for an approximate but often sufficiently accurate representation of the neutron flux distribution throughout the reactor core.

Monigruppidiffuusio is widely used in nuclear reactor design and analysis due to its computational efficiency. It provides a good balance between accuracy and speed, making it suitable for performing numerous calculations required for optimizing reactor core configurations, predicting fuel burnup, and assessing safety parameters. The accuracy of the results depends on the number of energy groups used and the quality of the nuclear data employed.