MCNPX Fatal error: "electron importances are zero"

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.

Try looking at Section 2.9 in the this Users Manual.
TechReport_2017_LANL_LA-UR-17-29981_WernerArmstrongEtAl.pdf

(above found with:
https://www.google.com/search?hl=en&q=MCNPX+"electron+importance")

Line 124 in your attachment sets it to Zero.

Cheers,
Tom

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.

Tom.G said:

Try looking at Section 2.9 in the this Users Manual.
TechReport_2017_LANL_LA-UR-17-29981_WernerArmstrongEtAl.pdf

(above found with:
https://www.google.com/search?hl=en&q=MCNPX+"electron+importance")

Line 124 in your attachment sets it to Zero.

Cheers,
Tom

Thaks for your comment...it was very helpful