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Unstructured Mesh with Attila4MC

Date:Monday July 22, 2024 through Friday July 26, 2024
Time:9:00-11:30 and 1:00-4:00 (US Mountain Time); only AM session on Friday
Place:Los Alamos, NM, USA
Maximum Enrollment:12
Minimum Enrollment:8
Prerequisites:A basic knowledge of MCNP is required either through one of the MCNP classes or a year's hands-on experience with MCNP. Attendees should be familiar with using a Windows command window and text editors.

Other key dates:

  • May 03, 2024, non-US citizen registration deadline.
  • June 24, 2024, class go / no-go determination and refundable withdrawal deadline.
  • July 08, 2024, late-registration deadline.

See Other Details below for more information on these dates.


This class is an introduction to the unstructured mesh capability in MCNP6 and the Attila4MC problem-setup Graphical User Interface (GUI) from Silver Fir Software taught by LANL and Silver Fir Software personnel. In this class, the participant will learn how to develop 3-D geometries in SpaceClaim, import these CAD geometries into Attila4MC, mesh the geometry, setup the entire MCNP6 input file with the GUI, and run the calculation using the MCNP6 unstructured mesh capability.

The participant will also learn about the Attila4MC variance reduction tools: (1) The Attila solver to generate weight windows with the FW-CADIS and CADIS methodologies and (2) GUI based tool to automatically calculate cell importances for use in the traditional geometry splitting and roulette game.

The MCNP6 pre- and post-processor programs will be covered. Post-processing of MCNP6 solutions for visualization will be covered, enabling the user to produce 3D contours, 2D slices, and various other plots of the unstructured mesh solution.

Participants will be provided with installation packages and temporary licenses for SpaceClaim version 2023 and Attila version 10.3, if available. If Attila version 10.3 is not released in time for this course, then version 10.2 will be provided. Attila version 10.3 will add some useful features but is functionally and visually the same as version 10.2. The training provided in this class will be relevant to both versions regardless of which is provided. Licenses and software will be distributed by the LANL point of contact at least one week before the class to allow time to resolve any installation issues.

The material is organized with group exercises and demonstrations. There will be an open lab where the participant can work on a problem of choice, either one that they bring or one from the class exercise pool.

Class instructors are from LANL and Silver Fir Software, so pre-class communication will come from both organizations to assist students with pre-class preparation.

The class will be based on version 6.2 or later of the MCNP code.

Topics include:

  • Introduction to the MCNP6 unstructured mesh / hybrid geometry capability.
  • Overview of Attila4MC and CAD modeling.
  • Introduction to SpaceClaim.
  • Creating models with SpaceClaim.
  • CAD cleanup / defeaturing with SpaceClaim.
  • Problem setup with the Attila4MC GUI.
  • Student exercise: creating an input from scratch.
  • Post-processing visualization.
  • Using Attila4MC automated importance generation for variance reduction.
  • Introduction to deterministic transport & deterministic weight windows.
  • FW-CADIS and CADIS with Attila4MC using CAD models.
  • Introduction to multiple unstructured meshes and CSG hybrid geometry in MCNP6.
  • MCNP6 unstructured mesh pre- and post-processors.
  • Introduction to MCNP activation and shutdown dose rate calculations using Attila4MC
  • Student exercises.
  • Open lab.
  • Please address all correspondence regarding this class to the MCNP Registrar.

    Next Steps after Registering

    Your registration is not complete until the following documents have been submitted to the MCNP Registrar. Everyone must:

    1. Submit proof of an MCNP license.
      • For those who received access to the MCNP code from RSICC, submit either:
        • RSICC license PDF (example, preferred), or
        • RSICC request history (example). An email with this history is automatically sent to you after authenticating with the RSICC Order History webpage and verifying contact information.
      • For those who received access to the MCNP code directly from LANL: submit the fully approved software-distribution form you received when access was granted.
    2. Submit a completed MCNP class request form.
      • A frequently asked question is "Why do I have to fill out this form when I just registered?" Unfortunately, the processes that need to be followed to admit students to MCNP classes require these two sets of data to be submitted, processed, and kept separately. We apologize for the inconvenience.

    In addition, all non-US citizens must:

    1. Submit image(s) of identification document(s) in the form of either:
      • Official government identification card (acceptable for online classes), or
      • Passport name/photo pages and any applicable visa(s) (required for in-person classes) or
      • US Permanent Resident card (i.e., the USCIS I-551 form also known as a "green card"), if applicable. Submit images of front and back.
    2. Submit detailed résumé or curriculum vitae with the following details (download an example Microsoft Word document):
      • Company/school name, location (city/country), position held, and dates of employment (start and end month/year).
      • The employment and education from the time of turning 18 years old must be accounted for with no gaps.
    3. Clearly indicate all citizenships when asked about citizenship. If born in a country not listed in 10 CFR 810, then evidence of non-citizenship and/or renunciation of birth-country citizenship must be provided.

    Before the class starts, all participants:

    • Must obtain and install the MCNP6 code.
      • The executable version is sufficient for class purposes. Directions to request the code from RSICC can be found here. Note that LANL employees follow a different process to acquire access to the MCNP code.
    • Must submit registration fee promptly upon notification.

    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://about.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:
        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.

    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 June 24, 2024) notifying them if a class is cancelled because of low enrollment.


    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 June 24, 2024), 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 July 08, 2024) 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 May 03, 2024. 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 MCNP6.2.
      • 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.
      • 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.

    Visiting Los Alamos


    Visitors to Los Alamos National Laboratory (LANL) usually fly into either Santa Fe Regional Airport (SAF) or Albuquerque International Airport (ABQ).

    Google Maps-based driving directions from each are:

    Other LANL-focused arrival information is available here.

    When arriving at Los Alamos National Laboratory, all vehicles pass through a vehicle access portal (VAP) where drivers will need to present current photo identification such as a state-issued driver's license or LANL-issued badge. Note that the VAPs on the Pajarito corridor require a LANL-issued badge.

    All visitors must obtain a badge as the first part of their visit. Identification requirements as of August 2023 are listed here. The LANL badge office (and the MCNP classroom) are located in the

    Otowi building on Casa Grande Drive.
    The hours are currently 0700–1530 MDT and badging questions can be answered by calling 505-667-6901.


    Several of the hotels that serve Los Alamos are:


    Dining information is available through the Los Alamos Chamber of Commerce with a downloadable summary here.