thank you dear the problem has been solvedAlex A said:Hello @ameermukhtar,
Welcome to PhysicsForums. Your bounding sphere defines the experiment area, and anything outside it is part of the void. That works so long as no objects poke through. If you run "mcnp ip inp=filename", the default view seems fine. But click on the input box and type "pz 149", to check close to corners of 9 and 10, you can see the corners of 9 (rpp) sticking through it. Just try making the sphere bigger and see if that fixes the problem.