The Joint Evaluated Fission and Fusion (JEFF) project is a collaboration between NEA Data Bank and participating countries to develop a reference nuclear data library. The JEFF library contains sets of evaluated nuclear data in a number of different types. The JEFF project’s hybrid meeting was held on 22-26 November 2021, with over 100 delegates and invited experts. Some attended the event at the Château de la Muette for the first time since 2019 while others participated virtually. Over the course of 2021 the project has been reformed with now just 11 technical working groups covering traditional topics as co-ordination with differential nuclear physics measurements as well as groups to address emerging fields such as the application of machine learning to data evaluation and testing.
The JEFF Co-ordination Group agreed to establish a new project management group to oversee deliverable-focused mechanisms that include regular reviews of the status of new measurements, evaluations and validation results. Technical decision-making meetings are now being launched in parallel to the nuclear data week conferences to agree the precise specifications of products including perturbed files for uncertainty quantification and first-of-a-kind correlations for physics data such as thermal scattering and neutron-induced fission yields. The latter have been developed in partnership with the NEA Working Party on International Nuclear Data Evaluation Co-operation. The project has agreed a detailed roadmap and reconfirmed the goal to release a general-purpose JEFF-4 library in 2024.