MCNP PTRAC card help

Thread starter MadGander
Start date May 12, 2025
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Mcnp Nuclear engineering

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SUMMARY

The discussion centers on using the PTRAC card in MCNP to analyze particle interactions with a specific cell and their contribution to a surface tally. The user reports issues with the PTRAC output being unintelligible and seeks clarification on the meaning of the output message indicating "binary file ptrac written with 10000 events from 9111 histories." This message confirms that 9111 simulated particles met the criteria set by the PTRAC card, and the user is encouraged to refine their input deck for clearer results.

PREREQUISITES

Familiarity with MCNP (Monte Carlo N-Particle Transport Code)
Understanding of the PTRAC card functionality in MCNP
Knowledge of surface tally methods in particle transport simulations
Basic skills in interpreting MCNP output files

NEXT STEPS

Review the MCNP documentation on the PTRAC card for detailed usage guidelines
Learn how to properly configure surface tally parameters in MCNP
Investigate common troubleshooting techniques for MCNP output issues
Explore advanced filtering options in MCNP to refine simulation results

USEFUL FOR

Researchers, nuclear engineers, and simulation specialists working with MCNP who need to analyze particle interactions and improve the accuracy of their simulation outputs.

May 12, 2025

MadGander

TL;DR: Need help setting up and interpreting my PTRAC output.

Hi all,

I'm attempting to simulate a very specific setup in MCNP. I want to know the fraction of particles contributing to a surface tally that previously interacted (scattered) with a specified cell. I'm currently doing this via the PTRAC card as well as FILTER. Currently, my PTRAC is outputting gibberish. I'm also curious what the number is at the bottom of my regular output... "binary file ptrac written with 10000 events from 9111 histories." Does this mean 9111 simulated particles fit the requirements of the PTRAC card? I've attached my input deck below. Any help is appreciated.