The Joint Evaluated Fission and Fusion File (JEFF)  Nuclear Data Library Project  is a collaboration between NEA Data Bank participating countries. The JEFF library combines the efforts of its different working groups to produce a common set of evaluated nuclear data, mainly for fission and fusion applications. The JEFF project meets twice a year, in autumn and spring. The latest edition of the Nuclear Data Week took place on 24-28 April 2023, and hosted both the JEFF Co-ordination Group and the JEFF technical sessions.

In 2023 the JEFF Nuclear Data Week included presentations from the NACRE project. This was a great opportunity to strengthen the interaction between the two projects, and to discuss opportunities for experiments that could be supported by NACRE and are of interest to the wider JEFF community. 

The integrated project NACRE has been supported by the French NEEDS programme since 2016. Its main objective is to create the conditions for close collaboration between experimenters, theorists and evaluators from CNRS-IN2P3, CEA and IRSN institutes. The different actors of the project are involved in order to provide on the one hand, concrete answers on the evaluation of nuclear data of interest to some crucial "systems" for reactors and on the other hand, to participate in the improvement of methods and techniques used at different stages of the nuclear data evaluation chain. Both the instrumental aspects and the control of uncertainties as well as theoretical developments and evaluation methods are an integral part of this project. It takes advantage of the know-how of different collaborations, the installations/models/tools to which they have access or that they develop, by refocusing the objectives on the improvement of the evaluated databases.

The project is built on three work packages dedicated to the:

1. measurement/evaluation of cross sections;
2. measurement/evaluation of fission yields;
3. experimental study of the fission products decay and the associated evaluation activities.

Proposed sessions:

• Experiments
• Fission observables
• Decay data
• Evaluation methods
• Nuclear data uncertainties
• Thermal scattering law
• Benchmarking
• Processing
• Depletion 
• Machine learning
• Theory and models
• Radioprotection 
• Fusion
• JEFF-4 Status
• Co-ordination Group (upon invitation only)

Please note that the following was a draft schedule and subject to change. 

• 10 February – Registration opening date
• 13 March – Draft of the timetable
• 24 March – Registration closing date for speakers
• 31 March – Finalisation of the agenda
• 7 April - Registration closing date for audience members