MCNP error zero lattice element hit

In summary, the speaker is encountering a "zero lattice element hit" when trying to run a hexagonal lattice in MCNP5. They are seeking help to solve this issue and are considering extending the lattice or filling the missing wedges with another material. They also mention having to limit the lattice to 7x7 and adjusting dimensions in the cluster surface. The expert also questions the presence of fractional pins in the fuel array.
  • #1
TL;DR Summary
I have been encountering "zero lattice element hit" when I try to run it in MCNP5. The input file is provided below. The square lattice runs fine, but the hexagonal does not. Hope someone can help me here. Thank you.
I have been encountering "zero lattice element hit" when I try to run it in MCNP5. The input file is provided below. The square lattice runs fine, but the hexagonal does not. Hope someone can help me here. Thank you.
 

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  • finalhexa.txt
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  • finalsquare.txt
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  • #2
That was diverting. :biggrin:

You have a hexagonal lattice filling a cylinder.

You have a hexagonal lattice almost filling a cylinder. A "zero lattice" means that nothing has been provided in a part of the lattice that a particle has arrived at. The white wedges have nothing in them. You can either extend the lattice and fill with some more pins. Or you can fill those wedges with something else. Or you can set their importance to zero.

Probably what you want is to define a new universe and fill it with something. Void or zirc or water or whatever makes sense. Then fill past the pins a step in i and j with that new universe.

homeless.png
 
  • #3
thank you very much for your help...I thought the problem was more complicated than that :). My problem with the hexagonal lattice is that I have to limit it to a 7x7 lattice and try to put it in a "circular" cluster surface. Maybe, it would be easier to adjust the dimensions in the cluster surface (#s 69-72). Again, thank you for your help :)
 
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  • #4
Out of curiosity, I was wondering about those fractional pins. Do you really want them in there? I would have expected a fuel array to consist of complete pins. With the placement you have, you have 19 complete pins in a nice 3-pins-on-a-side hexagon, and then a bunch of partial pins. What's up with that?
 

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