WIMSD-5B is one of the few reactor lattice codes available on non-commercial terms. It is used widely in many laboratories for research and power reactor calculations. One of its limitations was the associated nuclear constants library, which was based on nuclear data originating from the 1960s, with empirical adjustments to improve its performance. To remove this deficiency, a new library has been generated, based on the most recent evaluated nuclear data files. This publication describes the definition of constants, the data processing methods and an extensive list of more than 200 analysed benchmarks that were used for library validations, and supports the newly generated library.
