WPEC Expert Group on the Recommended Definition of a General Nuclear Database Structure (EGGNDS)

The Evaluated Nuclear Data File (ENDF-6) nuclear data format has had a long and fruitful history as the preferred format for storing and exchanging evaluated nuclear data. Together with processing codes, it plays a pivotal role in connecting nuclear physicists and reactor physicists, allowing them to exchange data between different computer codes. Today, however, it is showing signs of age. In particular, the ENDF-6 format places unnecessary limitations on the types of reactions and the level of precision at which data can be stored, making it more difficult to ensure the quality and consistency of the data. Modern users are applying nuclear data towards solving a broad range of problems (in medical physics, global security and advanced detector designs, among others) that stretch the ENDF-6 format beyond its original design.

Purpose, scope and membership

In order to take the next step, it has become necessary to establish an international expert group to endorse, promote and maintain the new format as the future international standard for disseminating nuclear reaction databases. Therefore, the Expert Group on the Recommended Definition of a General Nuclear Database Structure (EGGNDS) will become the steward of a new international definition for the modern nuclear database structure.

Up to two official representatives from each WPEC nuclear data evaluation project or institution will recommend definitions of the GNDS. Currently, these entities include the Evaluated Nuclear Data File (ENDF), Japanese Evaluated Nuclear Data Library (JENDL), Russian Library of Evaluated Neutron Data Files (ROSFOND/BROND), Joint Evaluated Fission and Fusion Nuclear Data Library (JEFF) and the IAEA.


The main objectives of the expert group are to make the GNDS:

  1. easier for new users, as well as current users, to contribute to the community
  2. general and useful enough that it could also be used to organise nuclear structure data, experimental data and other nuclear data products
  3. adhere to high-quality assurance and documentation practices.

Other goals include the development of better open-source infrastructure to manipulate, search, plot, process, translate and check nuclear data and the development of new nuclear data products heretofore not possible. The expert group, in close collaboration with the subgroup on infrastructure (WPEC/SG43), will ensure that important and useful tools for using the new recommended definition are developed and maintained.

The EGGNDS guides the creation of new infrastructure and promotes better evaluation practices. It is foreseen that it will release new GNDS versions with appropriate documentation as necessary, without overburdening stakeholders.


The expert group ensures the recommended definition of the GNDS meets the needs of major international nuclear data communities. In addition, the expert Group works on the following deliverables:

  • release the initial GNDS version and periodic updates
  • choose a collaborative platform and establish practices to maintain and discuss the recommended definition
  • organise workshops to train evaluators and other members of the nuclear data community, especially users, on the new structure.

Subgroup 38 (SG38) – Beyond the ENDF format: A modern nuclear database structure

SG38 was formed in 2012 to solicit feedback from international stakeholders and develop a new General Nuclear Database Structure (GNDS) for storing nuclear data to replace the legacy ENDF-6 format. The SG38 has met its stated goal to develop a nuclear data structure definition that can meet the needs of a broad set of nuclear data users and providers.

Subgroup 43 (SG43) – Code infrastructure to support a modern general nuclear database (GND) structure

SG43 was formed in 2016 to emphasise the development of open source tools capable of reading and writing GND-formatted data as defined by SG38. Developing these tools will not only encourage adoption of the new format but will also provide practical feedback about the GND format requirements and specifications.

Related topics
  • Nuclear science
  • Nuclear data
  • Mailing lists

    EGGNDS mailing list for questions, comments or to consult archives

    SG38 mailing list for questions, comments or to consult archives

    SG43 mailing list for questions, comments or to consult archives


    NEA GitLab space for EGGNDS (please contact WPEC if you do not have access permissions)

    NEA GitLab space for SG43 (please contact WPEC if you do not have access permissions)

    External links




    Andrew Holcomb