Why Does Changing the Splitting Mesh in MCNP5 Affect Histories and File Outputs?

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Changing the splitting mesh in MCNP5 can significantly impact the number of histories generated and the output files produced. Initially, an overly complex splitting mesh with too many fine intervals led to an excessive number of collisions, preventing any histories from being recorded. After reducing the number of splits, histories were generated, but issues with the weight window output file persisted, including warnings about particle escape from the mesh. The underlying problem was traced to a conflict between the OpenMPI and MPICH2 libraries. Understanding these library interactions is crucial for effective MCNP5 usage and output management.
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HIya, I am not actually sure why this is happening so was wondering if anyone can help.

im running in photon mode and I am trying to generate a weight window. initially i think my splitting mesh was over done a little bit (ok too much say about 15 fine intervals in a 10cm region) and i wouldn't go past one history. just billions of collisions were occurring. I reduced the number of splitting and now I am getting histories but why did this happen? my geometry is fine but is very complicated.

now that I am getting histories, and scoring in some of the regions i want but I am not getting a wwgout file. i do, however, get a warning saying some of my particles have escaped the wwg mesh.

thanks in advanced. i am relatively new to mcnp but I am on a mission to learn this!
 
Engineering news on Phys.org
The problem is Solved.
It was because of the conflict of libraries (openmpi and mpich2).
 

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