The discussion addresses a common issue in MCNP where the automatic volume calculation fails for a sliced geometry in a torus structure. Users can resolve this by manually specifying the volume in the cell definition using the "vol=" parameter or by employing a divisor card (SD). For thin slices resembling cylinders, an approximation using the formula Pi*200*200*70*2 is suggested. This approach is particularly relevant when the cell includes a tally.
PREREQUISITESMCNP users, computational physicists, and researchers working with complex geometries in Monte Carlo simulations will benefit from this discussion.
Thank you so much for your answer Alex but in output file,Alex A said:Hello @Osas, welcome to PhysicsForums.
It's quite common for the automatic volume routine to fail. The actual volume can be added to the cell definition using "vol=", or with a divisor card SD. Usually it's only needed if the cell has a tally. Such a thin slice is quite close to a pair of cylinders, so Pi*200*200*70*2 might be good enough for most purposes.