MCNP Input of Voxel Arrays and Their Universes

AI Thread Summary
The discussion revolves around troubleshooting errors in MCNP input related to voxel definitions and geometry issues. Users report encountering fatal errors such as "the surface type is not recognized" and "zero lattice element hit," indicating potential geometry errors or misdefined surfaces. Suggestions include checking for extra line breaks and ensuring correct definitions of cell cards and surfaces. One user also seeks assistance with a "cell 2 have no fill" error while trying to run their code. Resources like a primer on common MCNP problems are mentioned, but some users report broken links.
njm
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Hi
I have problems in mcnp input of voxels. I define a voxel arrays and their universes,for example universe1 is defined as:
2001 43 -1.030 -70 u=1 vol=6.795352
but in runing I have below error:
fatal error.the surface type is not recognized: -1.03
While 1.03 is the density of material43!

Can anyone help me?
 
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njm said:
Hi
I have problems in mcnp input of voxels. I define a voxel arrays and their universes,for example universe1 is defined as:
2001 43 -1.030 -70 u=1 vol=6.795352
but in runing I have below error:
fatal error.the surface type is not recognized: -1.03
While 1.03 is the density of material43!

Can anyone help me?

It sounds like you are trying to define a cell card in the surfaces section. Do you have an extra line break somewhere?
 
oh yes!
thank you very much
 
Now I have this error:
zero lattice element hit.
what is it?!
How can I solved it?!
 
Last edited:
Thanks you so much for your help.
 
Yrrepy said:
if you have a zero lattice element hit: it usually means you have a geometry error, overlapping cells, mis-defined cell surfaces etc

check out this primer

at the end is an excellent summary of common problems and their solutions

http://www.google.com/url?sa=t&rct=...W1oaVs&usg=AFQjCNHBUq22eV7EEAikLl32QV2VWK3LnQ

I am having the similar problems while running my script. I get this error

bad trouble in subroutine newcel of mcrun
source particle no. 2804404
starting random number = 132729341823053
zero lattice element hit.
run terminated because of bad trouble.

I suspect it has to do with something the code says before it starts that surface 42 appears more than once in a chain.
Does anyone have an idea of what it could be? And also the link to that primer doesn't work does anyone have a new link to it?
 
Hi,
I am trying to do similar , but first I must learn basic stuff...
When I try to run code (down below) i get fatal error cell 2 have no fill?

1 1 -1 -1 fill=1 imp:n=1
2 1 -1 -2 lat=1 u=1 imp:n=1
3 0 1 imp:n=0

1 box -5 -5 -10 10 0 0 0 10 0 0 0 20
c 1 REC 0 0 0 0 0 70 20 0 0 0 10 0
2 box -5 -5 -10 1 0 0 0 1 0 0 0 1
c box -1 -1 -1 1 0 0 0 1 0 0 0 1

m1 94239.66c 1.0
c tally
f4:n 1 (2<2[0:9 0:9 0:19])
sdef pos .1 .1 .1
print

Any tips?

Cheers..
 

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