Flux maps error for Triangular lattice

Hi all,
I had a very strange problem with the triangular lattice calculation,the Flux_mps.png shows the flux maps of a triangular lattice contained Three identical fuel elements,One-sixth of each fuel element is located at a 60-degree Angle of an equilateral triangular lattice.

All three sides of the triangle use reflective boundary conditions

Theoretically, the flux distribution of these three fuel rods should be the same, but it is very strange that the flux of the fuel element rod at the top angle is higher than that of the other two. Can someone help me to answer it? Thank you very much.

@zhaozelong If everything is truly symmetric, as you said the flux should be the same in each of the three fuel elements. Do you have a model you can share that demonstrates what you are seeing?

Hi paul,
This is my python script for modeling and simulation. In recent days, I try to modify the input, I found that different spatial distribution of kcode source,different keff will be obtained,and the flux maps is still wrong.
Maybe this is due to that the neutron mean free path is equivalent to the geometric size, so the source distribution will affect the results?Thanks for the reply.

sca_4b_lat_b.py (13.2 KB)