Using NJOY to Create MCNP ACE Files and Visualize Nuclear Data

Date:	Monday August 31, 2026 through Thursday September 03, 2026
Time:	6 hours per day, which will be selected based on international participation
Place:	WebEx Online Environment
Maximum Enrollment:	20
Minimum Enrollment:	10
Prerequisites:	Class attendees are expected to have some experience with the MCNP code.
Cost:	$900
Status:	Canceled

Other key dates:

• June 12, 2026, non-US citizen registration deadline.
• August 03, 2026, class go / no-go determination and refundable withdrawal deadline.
• August 17, 2026, late-registration deadline.

See Other Details below for more information on these dates.

Summary

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 or later 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.

Payment Options

The class fee includes a collection of files with all class slides (over 600), handouts, and other reference material.

There are four payment options, with credit card being the preferred option. Details about each method follows.

1. Credit card (preferred)
• Visa, MasterCard, or Discover Card are accepted for payment.
• Please pay at: https://www.lanl.gov/lanl-resources/payments-to-the-lab and select MCNP Training from the dropdown menu.
• Payment Description: Class title and date. If another individual will be making payment on your behalf, please have them include your name in this field.
2. Check
• Please make out your check (US dollars only) payable to: Los Alamos National Laboratory/UT32
• Make sure your name appears on accompanying documentation with the check.
• Mail the check to:
  Cashiers
  Los Alamos National Laboratory
  P.O. Box 1663, MS P231 Los Alamos, NM 87544 USA
3. Wire transfer
• Please email the MCNP Registrar with a request for wire transfer bank information.
4. Internal cost code (LANL employees must use this)
• Please email the MCNP Registrar and provide a complete cost code and organizational code.
• We will not charge the cost code. It is used only for bookkeeping.
• Full participation in the class is expected.

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 before the class start date (by August 03, 2026) notifying them if a class is cancelled because of low enrollment.

Refunds

If the class is cancelled because of 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 for another reason and cancel your registration less than four weeks in advance (after August 03, 2026), 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 (after August 17, 2026) may be accepted on a space-available basis and 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 June 12, 2026. 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.

Pre-class Information

Students who are fully registered and have confirmed payment for the class are ready to attend. This webpage lists the details needed to attend.

However, prior to arrival the student must accomplish two critical steps with the computer he or she will use for the class:

1. Install and test MCNP6.2 or MCNP6.3.
• In addition to the installation instructions provided with MCNP6.2, a YouTube tutorial for installing MCNP6.2 on Microsoft Windows is available. This video concludes with steps to test the installation to ensure the software is configured as required for most MCNP classes.
• A similar YouTube tutorial for installing MCNP6.3 on Microsoft Windows is also available.
• For in-person classes, it is strongly recommended that the installation DVDs also be brought (and a way to read them) in case the code needs to be reinstalled on the student's laptop during the class.
2. Download the class materials (presentations, example input files, etc.).
• A download link for a ZIP file containing class materials will be provided to registered and fully paid attendees the week, typically the Thursday, before the class.
• The download is approximately 500 MB and should be fully extracted for use.

For WebEx-based classes, WebEx connection information will be provided to registered and fully paid attendees the week, typically the Thursday, before the class.