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Using NJOY to Create MCNP ACE Files and Visualize Nuclear Data

Date:Monday August 29, 2022 through Wednesday August 31, 2022
Time:10:00-5:00 (US Mountain Time)
Place:WebEx Online Environment
Maximum Enrollment:40
Minimum Enrollment:20
Prerequisites:Class attendees are expected to have some experience with the MCNP code.


This class will introduce participants to the Evaluated Nuclear Data File (ENDF) format and the NJOY Nuclear Data Processing System that can be used to produce nuclear data application libraries from it.

Time will be available to discuss NJOY capabilities that are of interest to class participants.

The class will be based on version 6.2 on the MCNP code and the current version of the NJOY code, NJOY2016, available here.

Topics include:

  • Introduction to ENDF
  • History of NJOY
  • How to obtain the code package and update the source code to create a new executable
  • Create input decks and examine the associated output from the basic components of NJOY required to produce MCNP continuous energy neutron ACE files and MCNP thermal scattering ACE files
  • Create input decks for NJOY's PLOTR & VIEWR modules to visualize cross sections and their ratios, scattering angular distributions, & secondary spectra.
  • Run MCNP with newly processed data.
  • Create multigroup data files using NJOYs GROUPR module.
  • Convert incident neutron nuclear data files in the ENDF format into MCNP continuous energy (.c) ACE files,
  • Plotting nuclear data using NJOY.
  • Convert ENDF formatted thermal scattering law files into MCNP (.t) ACE files.
  • Utilize newly processed data in MCNP.
  • Processing nuclear data into multigroup data files.
  • Please address all correspondence regarding this class to the MCNP Registrar.

    Other Details

    Minimum Class Enrollment

    There is a minimum number of participants required for each class to be held. Registered class participants will receive an email no later than four weeks (the cut-off date) before the class start date to confirm that the class will be held as scheduled or to announce cancellation due to low enrollment.


    If the class is cancelled due to low enrollment, participants may request a refund of any registration fees paid or may request that the fee already paid be credited towards their attendance at a future class.

    If you cannot attend the class and cancel your registration less than three weeks in advance, we will be unable to refund any registration fee paid. However, the fee may be applied towards attendance at a future class. Alternatively, another person from your organization may attend in your place, depending on the citizenship of that individual. Contact the MCNP Registrar for further information.

    Last-minute Registrations

    Registrations received within two weeks prior to the start of a class may be accepted on a space available basis, depending on the citizenship of the person registering.

    Non-US Citizens

    Registration requests for non-US citizens who are citizens of a country listed in US Regulation 10 CFR 810 are processed by the LANL Foreign Visits Office. This security approval processing is based on requirements issued from the US Department of Energy. The processing normally takes at least 60 days. You must register and provide all requested information by the deadline shown on the MCNP Class Schedule page. Although we can never guarantee that a security approval will be received, we will make every attempt to obtain an answer for your attendance request as soon as possible.

    Registration requests for non-US citizens who are citizens of or reside in a country not listed as a Generally Authorized Destination in US Regulation 10 CFR 810 cannot be processed by LANL and will be submitted directly to the Department of Energy.

    For a list of 10 CFR 810 countries, please go to the Electronic Code of Federal Regulations, 10 CFR 810.