The Joint Evaluated Fission and Fusion (JEFF) Nuclear Data Library is a collaboration between NEA Data Bank participating countries to produce a common set of evaluated nuclear data, mainly for fission and fusion applications. The JEFF project meets twice a year, in the spring and autumn, for a JEFF Nuclear Data Week with the aim of promoting co-operation between experimentalists, evaluators, producers and end-users of nuclear data.
The NEA hosted the Nuclear Data Week from 14 to 18 April 2025 in Boulogne-Billancourt, France. This event brought together experts from the JEFF nuclear data library project to advance the development of JEFF-4.0, the forthcoming major update to the library.
The week featured technical sessions covering various topics, including experiments, thermal scattering laws, fission observables, decay data, theoretical models, evaluation methods, nuclear data uncertainties, processing, benchmarking, and depletion. A dedicated session addressed the current status of JEFF-4.0, underscoring the collaborative effort to finalise this new release. The group outlined plans for the accompanying documentation, underlining the commitment to transparency and comprehensive information dissemination.
The co-operation during the week underscored the commitment of the international nuclear data community to deliver a comprehensive and validated JEFF-4.0 library, supporting both fission and fusion applications.
