Hi @bentridisalah ,
There’s some difference in using [MeshFilter and CellFilter ] I got the result which are similar to serpent by using MeshFilter, However, I would prefer to use the CellFilter as I’m doing Multiphysics calculation loop and changing reactor block height, dealing with Meshfilter will be really complicated. so It’s just a temporary solution.
Here’s what I found : Difference in Fission rate Tally value from MeshFilter and CellFilter