ABSTRACT
The most popular cross section libraries in Version 7 are measured at a temperature of 300 degrees Kelvin, or about 27 degrees Centigrade. Some well-respected neutron cross section libraries use only 100 or 200 energy groups, while some other libraries have attempted to use as many as 10,000 different energy groups. In the case of a light water reactor, a single cross section library can be created with 1000 energy groups that it is applicable to all fuel assembly and reactor criticality calculations, as well as to all radiation shielding calculations. Adding a third energy group for the epithermal or resonance energy range can also improve the accuracy of the cross section library in some cases. The scattering cross sections are compiled from many different data sources, and there is a specific index number called an MT number that is used to identify them.
