Capability of processing the GNDS format evaluated nuclear data in NECP-Atlas for neutronics calculations

The Generalized Nuclear Data Structure (GNDS) has been being designed as the replacement of the conventional ENDF-6 format for the evaluated nuclear data libraries. The specification for the GNDS format was released by OECD/NEA in 2020. And the latest evaluated nuclear data libraries ENDF/B-VIII.0 and TENDL2019 were released in the ENDF-6 format and the GNDS format, simultaneously. The capability of processing the GNDS format evaluated nuclear data libraries is developed in the nuclear data processing code NECP-Atlas. To be compatible with the GNDS and ENDF-6 formats, the memory management method and the data structure in NECP-Atlas are modified to support more data beyond the ENDF-6 format. At the same time, a module called GNDS-Toolkit is developed to read, parse and convert the GNDS/XML format libraries. The ENDF/B-VIII.0 library in GNDS/XML format is processed into ACE format and multi-group libraries, and used in criticality calculations, lattice physics calculations and shielding calculations. The results show that the GNDS format libraries can be exactly processed by NECP-Atlas.