Complete data representing the relevant nuclear physics are required for the simulation of nuclear systems which require many types of data, such as particle and nuclei interaction probabilities, emitted particle energy spectra, angular distributions, fission product yield probabilities, decay properties and more.
To provide all of these data, large national and international programmes have been created to produce and maintain the databases of these physics, which are referred to as ‘nuclear data libraries’. These libraries are assembled through a complex process that involves many thousands of differential experimental data sets, the most sophisticated nuclear reaction modelling theory, inferences from large-scale experiments that are sensitive to changes in nuclear physics and a suite of software tools that prepare application-specific databases for all users. For organisations to use these data, they also need to be rigorously verified and validated using a set of benchmark experiments that are representative of the systems of interest.
Since 1989, the NEA has been co-ordinating projects on nuclear data through the Working Party on International Nuclear Data Evaluation Co-operation (WPEC), part of the portfolio of work within the Nuclear Science Committee (NSC). The major evaluated nuclear data library projects, the American Evaluated Nuclear Data File B (ENDF/B, US), the NEA Joint European Fission and Fusion File (JEFF), the Japanese Evaluated Nuclear Data Library (JENDL), the Russian Nuclear Data Library (ROSFOND, Russia) and the Chinese Evaluated Nuclear Data Library (CENDL) co-operate through the WPEC to raise targeted Subgroups that focus on a specific issue where worldwide attention will improve the state of the art. 50 subgroups have been created to address topics including new experimental measurements, uncertainties and correlations, verification and validation, specific evaluation topics, thermal scattering law data, fission product cross sections and yields, and more.
Two long-term expert groups under the WPEC are responsible for the High-Priority Request List (HPRL) for Nuclear Data, which maintains the world’s reference point for new nuclear data measurements, and the Generalised Nuclear Database Structure (GNDS), which has developed and maintains the specifications for the standard international nuclear data format that was first published in May 2020.
The NEA Nuclear Science Committee co-sponsors, at the request of the WPEC members, two international conference series on nuclear data:
The NEA's nuclear data evaluation co-operation activities involve the following evaluation projects: ENDF (United States), JENDL (Japan), ROSFOND/BROND (Russia), JEFF (other Data Bank member countries) and CENDL (China) in close co-operation with the Nuclear Data Section of the International Atomic Energy Agency (IAEA).