MCNP5: error in routine imcn

In summary, Jedishrfu thinks that the error you're seeing is caused by a combination of trailing spaces on the input cards and a missing library. He advises attaching the output file to a post so that others can see it and try to find a solution.
  • #1
TL;DR Summary
i am getting an error which reas as follows :
bad trouble in imcn in routine imcn source particle no error getting memorybly a control character,in coulumn 32
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  • #2
Have you tried to use google to search on the text of the error message?

mncp5 error: bad trouble in imcn in routine imcn source particle no error getting memorybly a control character,in coulumn 32

Sometimes other folks have had the same issue and you may find a solution.

We also have several threads at PF (shown below on the web page) where posters had similar problems with mncp5.
  • #3
Rename your output file to add .txt to the end, then attach it to a post.
  • #4
okey thank you bro


  • PWR.txt
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  • #5
While I'm not familiar with MNCP5, I looked through your file and noticed a few non-comment lines that had trailing spaces. There were a few lines with $ comments I think with trailing spaces too but I didn't think they would cause a problem.

See lines 85, 86 below which have an extra space at the end:

        40091.81c -1.10237E-01
        40092.81c -1.68499E-01

Could trailing spaces on your input cards cause the error you see?

I also saw a few blank lines, at lines 44, 59, 110, and 111. Should they instead be comment lines ie start with a "c"?

Lastly, should line #2 be a comment line eg c234567890123456789012 which I assume you added to locate column 32.
  • #6
When I change line 2 to
c 345678901234567890123456789012
the only thing that stops me running it is that I don't have ENDF VIII installed. When I make the changes to get it to run with the library native to 5, ENDF VI, (I removed .81c from the end of materials, and tin entirely), it just runs fine and gives a keff of 1.28.

Your actual error is strange btw, if it's 100% char for char your error. It looks like two normal MCNP5 errors smashed into one another. Reading the output file may provide more detail. I did ask for that, not the input file btw :) My thoughts now are maybe ENDF VIII is so new it's breaking the old MCNP 5 code. I may try installing ENDF VIII, but it needs a lot of disc space. Long and painful past experience makes me not trust very new libraries with old code. What version of 5 are you using and in what OS? It is also possible it's a linefeed or carriage return code issue which might be OS dependent. I ran with 5.1.60, which was the last release of 5, in linux.

@jedishrfu Just an FYI, the first two blank lines, in this case at 44 and 59, tell MCNP when the cell section and surface section end. Some aspects are quite arcane.
  • #7
.81c turns out to be ENDFVII, not VIII and I installed that. All the libraries can just be downloaded from here if anyone wants them.
With only the "c 3" change 5.1.60 is working so my main thought wasn't right.

1. What is MCNP5?

MCNP5 is a computer code used for simulating the transport of particles through matter. It is widely used in the field of nuclear engineering and radiation physics.

2. What does "error in routine imcn" mean?

This error message indicates that there was an issue with the imcn routine within the MCNP5 code. This routine is responsible for calculating the interactions of photons and neutrons with matter.

3. How can I fix this error?

The specific steps to fix this error will depend on the specific circumstances of your simulation and the cause of the error. Some potential solutions may include checking for typos in input parameters, adjusting the geometry or material definitions, or updating the version of MCNP5 you are using.

4. Can I prevent this error from occurring?

While it is not always possible to prevent this error from occurring, there are some steps you can take to minimize the likelihood of encountering it. These include carefully reviewing input parameters and definitions, using the most up-to-date version of MCNP5, and performing thorough testing and debugging before running a large simulation.

5. Where can I find more information about MCNP5 and troubleshooting errors?

There are many resources available for learning more about MCNP5 and troubleshooting errors. The official MCNP website, user manuals, and online forums are all great places to start. Additionally, seeking help from experienced MCNP users or attending MCNP workshops can provide valuable insight and support.

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