The JEFF Nuclear Data Library

The Joint Evaluated Fission and Fusion (JEFF) Nuclear Data Library is a collaboration between NEA Data Bank participating countries. The JEFF project combines the efforts of its different working groups to produce evaluated nuclear data sets for the peaceful applications of fission and fusion energy.

In its present mandate (2015-2018), the JEFF project is organized into the following working groups (WG):

JEFF library releases

The JEFF suite of nuclear data libraries contains a number of different data types, including neutron and proton interaction data, radioactive decay data, fission yields data, and thermal scattering law data. The latest official release of the neutron library is JEFF-3.2 (March 2014), available in ENDF-6 and ACE formats.

Ongoing developments

The JEFF project is currently focusing in the delivery of its next library release JEFF-3.3, which will include a thorough update to its neutron, decay data and fission yields library. JEFF-3.3 is scheduled for release at the end of 2017. In preparation of this release, a test neutron library is available for JEFF members under JEFF-3.3T4 (July 2017).

JEFF meetings

The JEFF project meets twice a year, in spring and fall, during the NEA Nuclear Data Week in a 5 day technical programme, with the aim to promote co-operation between experimentalists, evaluators and end-users of nuclear data involved in both projects.


For more information on JEFF activities please contact at NEA.

Last modified: 12 October 2017