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Variance Reduction with MCNP6

Date:Monday December 05, 2022 through Wednesday December 07, 2022
Time:9:00-11:30 and 1:00-4:00 (US Mountain Time)
Place:WebEx Online Environment
Maximum Enrollment:40
Minimum Enrollment:20
Prerequisites:This is an intermediate- to advanced-level class intended for users who have some familiarity with MCNP6 and understanding of variance-reduction techniques such as that gained through attending the Introduction to MCNP6 class.


This class focuses on applying variance-reduction techniques in MCNP6 fixed-source calculations. Class examples provide experience running the MCNP6 code, understanding particle behavior through code output, and applying/tuning variance-reduction techniques.

The class includes lectures and hands-on computer use for a variety of variance reduction calculations. Time will be available to discuss individual questions and problems with the MCNP developers, and to pursue additional variance reduction topics.

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

Topics include:

  • Brief review of particle transport, tallying, and statistics
  • Sampling, biasing, and statistical convergence
  • Understanding particle state with event logs
  • Implicit capture & weight rouletting review
  • Geometry-based importance splitting & rouletting review
  • Source biasing
  • Weight windows, and ways to generate them
  • Point detectors and DXTRAN
  • Forced collisions
  • Exponential transform
  • 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 four 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.