Can MCNP solve the geometric coincidence issue with a semi-cylinder and cuboid?

[chengmo]

How do we solve the geometric coincidence problem? I need a semi-cylinder that fits into the cuboid but if I use the cuboid and the cylinder directly it's geometrically problematic

 

[Alex A]

I'm not quite following the question. MCNP does Constructive Solid Geometry. Shapes are supposed to intersect and then you tell it which volumes are what part of the problem.

 

[chengmo]

I set up four cubes but only two are displayed. In my setting, there should be cuboids in the middle and under the ring. Why？

 

[Alex A]

In a cell definition a positive surface typically means above or outside. A negative surface means below or inside. If you take a look at cell 3, you have -3 4, meaning below x=4 and at the same time above x=6. The space between x=4 and 6 is "3 -4". Now have a look at cell 4 and see if you can find something similar.

 

[chengmo]

Thank you very much Alex A, I got the X-axis wrong. The sign of 1, 2,3, and 4 surfaces in the surface card is wrong

 

[chengmo]

However, after I corrected the error of x axis, the modeling problem still occurred in cell card 1. Why is cell card 2 and cell card 1 written in the same way? cell1 caused the problem, but cell2 did not

 

[Alex A]

MCNP seems happy. When I try the interactive plotter I see the full D. VisEd does not seem happy from your picture. Maybe VisEd does not like the comment. I do not see an error.