Computer Programs
PSR-0480 NJOY99.
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PSR-0480 NJOY99.

NJOY99, Data Processing System of Evaluated Nuclear Data Files ENDF Format

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To submit a request, click below on the link of the version you wish to order. Rules for end-users are available here.

Program name Package id Status Status date
NJOY99.24 PSR-0480/02 Tested 27-NOV-2000

Machines used:

Package ID Orig. computer Test computer
PSR-0480/02 Many Computers PC Pentium III 500,Linux-based PC,IBM RISC6000 WS
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More information on NJOY is available from the developer's home page at


The NJOY nuclear data processing system is a modular computer code used for converting evaluated nuclear data in the ENDF format into libraries useful for applications calculations. Because the Evaluated Nuclear Data File (ENDF) format is used all around the world (e.g., ENDF/B-VI in the US, JEF-2.2 in Europe, JENDL-3.2 in Japan, BROND-2.2 in Russia), NJOY gives its users access to a wide variety of the most up-to-date nuclear data. NJOY provides comprehensive capabilities for processing evaluated data, and it can serve applications ranging from continuous-energy Monte Carlo (MCNP), through deterministic transport codes (DANT, ANISN, DORT), to reactor lattice codes (WIMS, EPRI). NJOY handles a wide variety of nuclear effects, including resonances, Doppler broadening, heating (KERMA), radiation damage, thermal scattering (even cold moderators), gas production, neutrons and charged particles, photoatomic interactions, self shielding, probability tables, photon production, and high-energy interactions (to 150 MeV). Output can include printed listings, special library files for applications, and Postscript graphics (plus color). Follow the Tourbus section of the Tour area to find notes from the ICTP lectures held at Trieste in March 2000 on the ENDF format and on the NJOY code.


NJOY contains the following modules:

  • NJOY directs the flow of data through the other modules and contains a library of common functions and subroutines used by the other modules.

  • RECONR reconstructs pointwise (energy-dependent) cross sections from ENDF resonance parameters and interpolation schemes.BROADR Doppler broadens and thins pointwise cross sections.

  • UNRESR computes effective self-shielded pointwise cross sections in the unresolved energy range.

  • HEATR generates pointwise heat production cross sections (KERMA coefficients) and radiation-damage cross sections.

  • THERMR produces cross sections and energy-to-energy matrices for free or bound scatterers in the thermal energy range.

  • GROUPR generates self-shielded multigroup cross sections, group-to-group scattering matrices, photon-production matrices, and charged-particle cross sections from pointwise input.

  • GAMINR calculates multigroup photoatomic cross sections, KERMA coefficients, and group-to-group photon scattering matrices.

  • ERRORR computes multigroup covariance matrices from ENDF uncertainties.

  • COVR reads the output of ERRORR and performs covariance plotting and output formatting operations.

  • PURR generates unresolved-resonance probability tables for use in representing resonance self-shielding effects in the MCNP Monte Carlo code.

  • LEAPR generates ENDF scattering-law files (File 7) for moderator materials in the thermal range. These scattering-law files can be used by THERMR to produce the corresponding cross sections.

  • GASPR generates gas-production cross sections in pointwise format from basic reaction data in an ENDF evaluation. These results can be converted to multigroup form using GROUPR, passed to ACER, or displayed using PLOTR.

  • MODER converts ENDF "tapes" back and forth between ASCII format and the special NJOY blocked-binary format.

  • DTFR formats multigroup data for transport codes that accept formats based in the DTF-IV code.

  • CCCCR formats multigroup data for the CCCC standard interface files ISOTXS, BRKOXS, and DLAYXS.

  • MATXSR formats multigroup data for the newer MATXS material cross-section interface file, which works with the TRANSX code to make libraries for many particle transport codes.

  • RESXSR prepares pointwise cross sections in a CCCC-like form for thermal flux calculators.

  • ACER prepares libraries in ACE format for the Los Alamos continuous-energy Monte Carlo code MCNP.

  • POWR prepares libraries for the EPRI-CELL and EPRI-CPM codes.

  • WIMSR prepares libraries for thethermal reactor assembly codes WIMS-D and WIMS-E.

  • PLOTR reads ENDF-format files and prepares plots of cross sections or perspective views of distributions for output using VIEWR.

  • VIEWR takes the output of PLOTR, or special graphics from HEATR, COVR, DTFR, or ACER, and converts the plots into Postscript format for printing or screen display.

  • MIXR is used to combine cross sections into elements or other mixtures, mainly for plotting.


The latest patch to NJOY99 is available at

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NJOY99 consists of a set of modules, each performing a well-defined processing task. Each of these modules is essentially a separate computer program linked together by input and output files and a few common constants. The methods and instructions on how to use them are documented in the LA-12740-M report on NJOY91 and in the "README" file. No new published document is yet available.


NJOY99 is a cleaned up version of NJOY 97.107 that features improved consistency between different systems, more use of block structures, a consistent set of physical constants and support for the CCC-700/MCNP4C Monte Carlo Program.

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All 14 test cases ran in about three minutes on a Pentium III 500mhz with LF95 v5.5d.

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UPD 2.0: Portable Update Emulator.

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Package ID Status date Status
PSR-0480/02 27-NOV-2000 Tested at NEADB
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PSR-0480/02, included references:
- R.E. MacFarlane:
  (December 31, 1999)
- R.E. MacFarlane & D.W. Muir:
  The NJOY Nuclear Data Processing System, Version 91.
  LA-12740-M (October 1994)
- R.E. MacFarlane:
  New Thermal Neutron Scattering Files for ENDF/B-VI, Release 2.
  LA-12639-MS (ENDF 356) (March 1994)
- R.E. MacFarlane & D.C. George:
  UPD: A Portable Version-Control Program.
  LA-12057-MS (April 1991)
- R.E. MacFarlane:
  "How to NJOY ENDF-6", The International Workshop on NJOY,
  Saclay, France (April 1992)
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NJOY99 runs on many computers. Machine-specific updates are included for Cray, Sun, IBM RS/6000, SGI Origen 2000, and DEC Alpha workstations, plus Linux and DOS updates for PC. This version was tested on a Sun Ultra in 32-bit mode using
f77 and f90, on a Pentium III using linux g77 and Portland Group, Inc. Fortran, on a SGI Origen 2000 using f90, and on a Pentium III under DOS with Lahey LF95 and Absoft compilers.

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Package ID Computer language
PSR-0480/02 FORTRAN-90, FORTRAN-77
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A Fortran compiler is required is required on Unix (including Linux) systems. NJOY99 produces graphs directly in Postscript and no longer requires the proprietary DISSPLA software. The Unix distribution runs on Cray under UNICOS and on the systems listed below. NJOY requires the EGCS package which is included with the Redhat6.1 standard Fortran package and is also in the latest versions of GNU g77. UPD and NJOY99 executables created with the Lahey F95 v5.5d compiler in a DOS Window of WindowsNT 4 are included in the package.


RSICC installed this release on :


  • Pentium III under WindowsNT 4 with Lahey F95 v5.5d

  • IBM 43P-260 running AIX 4.3.3 with f77 and xlf90 6.1

  • DEC/Alpha 500au under Digital Unix 4.0D with Fortran 90 V5.1-594

  • SUN UltraSparc 60 under SunOS 5.6 using f77 5.0 and C version 5.0

  • SGI R10000 IRIX 6.5.5 with MIPSPro Fortran 90 7.3

  • Pentium III under WindowsNT 4 RedHat Linux 6.1 with g77 and EGCS.


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Contributed by: Radiation Safety Information Computational Center
                Oak Ridge National Laboratory
                Oak Ridge, Tennessee, U. S. A.


Developed by:   Los Alamos National Laboratory
                Los Alamos, New Mexico

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INFO.FIL    Information file
PSR480.PDF    Abstract of the code
README.1ST    How to start
README0.NEA   Code description & installation guide
README24      Description of updates 1 to 24
P480.PDF      Code documentation  (PSR-480/NJOY99,0)
\DOS       DOS version of the code
\TAR       unix version of the code
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  • B. Spectrum Calculations, Generation of Group Constants and Cell Problems

Keywords: Doppler broadening, ENDF/B, Monte Carlo method, charged particles, covariance matrices, cross sections, data uncertainties, discrete ordinate method, gamma radiation, kerma factors, kernels, neutrons, photon interaction, resonance integrals, scattering, self-shielding, thermal neutrons, thermal scattering, transport theory, unresolved region.