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Joint Evaluated Fission and Fusion (JEFF) Library version 3.1.2

The Joint Evaluated Fission and Fusion File is an evaluated library produced via an international collaboration of Data Bank member countries co-ordinated under the auspices of the NEA Data Bank. The new JEFF-3.1.2 general purpose library is in ENDF-6 format and contains incident neutron data for 381 isotopes or elements from 1-H-1 to 100-Fm-255.

Superseded library

Please note that this is a superseded library that was approved for formal release but has been replaced with a newer official library version.


The complete set of data, including the updated neutron files is available online:


There is no official reference for the 3.1.2 release. Users are requested to cite the 3.1.1 or general 3.1 JEFF release documentation.

Citation (JEFF-3.1)

NEA (2006), "The JEFF-3.1 Nuclear Data Library", JEFF Report 21, NEA No. 6190, ISBN : 92-64-02314-3, Available online.

Citation (JEFF-3.1.1)

NEA (2009), "The JEFF-3.1.1 Nuclear Data Library", JEFF Report 22, NEA No. 6807, ISBN : 978-92-64-99074-6, Available online.