MCNPX Fatal error: "electron importances are zero"

  • Thread starter Thread starter Elizabeth Vega
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SUMMARY

The forum discussion addresses a fatal error encountered in MCNPX related to "electron importances are zero." The issue arises from a blank line at Line 122, which MCNP interprets as the end of input, preventing the reading of subsequent lines that set importance values. Users are advised to consult Section 2.9 of the MCNPX Users Manual (TechReport_2017_LANL_LA-UR-17-29981_WernerArmstrongEtAl.pdf) for further guidance on resolving this error. Proper formatting of input files is crucial to avoid such issues.

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  • Understanding of MCNPX input file structure
  • Familiarity with the MCNPX Users Manual
  • Basic knowledge of electron transport simulations
  • Experience with debugging simulation errors
NEXT STEPS
  • Review Section 2.9 of the MCNPX Users Manual for input formatting guidelines
  • Learn about common input file errors in MCNPX
  • Explore best practices for setting importance values in MCNPX
  • Investigate troubleshooting techniques for simulation software errors
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Researchers, physicists, and engineers working with MCNPX simulations, particularly those encountering input file errors and seeking to optimize their simulation setups.

Elizabeth Vega
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When I run the application, I get an error message. Fatal error electron importances are zero, I can't find what's wrong in the code.
 

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Welcome to physicsforums Elizabeth,

Line 122 is blank and MCNP is interpreting that as end of input, so the lines that set the importance for the cells are never read. Those lines look fine to me. MCNP has a few quirks because the core code dates from the days of mainframes. Blank lines being the section breaks is probably the biggest gotcha.
 
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