MCNP Barrel Geometry Help

[wtobias]

Hey all. I am creating an MCNP input deck but my geometry is appearing red in the vised plot and I am receiving errors relating to the geometry and material card sections. Could anyone potentially help me figure this issue out?

 

[Alex A]

Hi @wtobias, welcome to PhysicsForums!

All problems need a void cell with importance 0, or particles transport forever. Every point in space must belong to only one cell and all space must be in a cell.

You are using surface 1 and 3 in what feels like inconsistent ways. I've ignored surface 1, and putting it back in is your job. If you need a cell between these think about what you need to do to create that.

For cell 111 to not include any of the rods, you have to mention them all. For example,

  111     0         -3 2
       #51 #52 #53 #54 #55 #56 #57 #58 #59 #60
       #61 #62 #63 #64 #65 #66 #67 #68 #69 #70
       #71 #72 #73 #74 #75 #76 #77 #78 #79 #80
       #81 #82 #83 #84 #85 #86 #87 #88 #89 #90
       #91 #92 #93 #94 #95 #96 #97 #98 #99 #100
       #91 #92 #93 #94 #95 #96 #97 #98 #99 #100
       #101 #102 #103 #104 #105 #106 #107 #108 #109 #110 imp:n=1

I've used cell 50 as the central rod and added 999 as the void. Does this start to make sense?

 

[wtobias]

Yes thank you that makes sense. I still run into a fatal error when defining the materials however. I define material 1 for cell 111 and material 2 for the new cell I made 112. I'm not exactly sure where I am going wrong with my input. Ill provide the updated copy of the code below that sends the error. all that was changed was the material definition in the cell section for cells 111 and 112.

 

[Alex A]

You have an extra blank line just before the material cards and the program stops reading. One blank after the cell definitions and one after the surface definitions is all you should have. There is also stuff beyond the 80 char limit, which makes my version unhappy, but a new copy might be fine with that. It was an old IBM mainframe punched card limitation. Lastly there are too few spaces here

   24052.80c -0.18 $ 18% Chromium for SS 304
   28058.80c -0.12 $ 12% Nickel for SS 304

5 spaces will tell the code you are continuing the last line.

 

[wtobias]

This helped thank you