Links to NJOY Web pages and Sites

NJOY:  Data Processing System of Evaluated Nuclear Data Files in ENDF format

Recent Unofficial Updates at the NEA Data Bank

Many of the proposed NEA updates for the releases NJO99.364 and NJOY2012.8 have been included in the official new patches NJOY99-up393 and NJOY2012-up50. Some of the older ones that were not accepted are given here.

These updates are compatible with the official NJOY patches NJOY99.393 and NJOY2012.50.

NJOY99 is no longer maintained by LANL.

For details please see comments in the patches.

 Official Updates (LANL)  
 Archive of Unofficial Updates and comments at the NEA Data Bank Through interaction with Dimitri Rochman and Go Chiba, the following patches have been added:
Note by Andrej Trkov: By patching NJOY to conform with the ENDF-6 formats, the JENDL-3.3 fission spectrum covariance files become unprocessable. To circumvent this drawback, the chmf35 code is provided, which is designed to check and correct MF35 covariance files. It includes the following features:
The processed IRDF-2002 library in dosimetry ACE format for the MCNP family of codes is available from

 US Web pages

Data Bank Web pages

Workshops / Meetings

  NJOY Notes and Forum
ENDF-6 Formats Manual - Data Formats and Procedures for the Evaluated Nuclear Data File ENDF/B-VI and ENDF/B-VII, CSEWG Document ENDF-102, Report BNL-90365-2009 Rev.1, Revised July 2010

Last update: 3 August 2017