A continuous energy neutron and photon transport code.
Photon transport is simulated in the fixed source mode.
Boundary conditions include vacuum, specular and white reflection, and periodic boundaries for reactor cell calculations. VIM uses standard Monte Carlo methods for particle tracking with several optional variance-reduction techniques. VIM has an automatic restart capability to permit user-directed statistical convergence. The starting neutrons for each subsequent generation are randomly selected from the potential fission sites in the previous generation. Track-length or collision estimates of reaction rates are automatically tallied by energy group and edit region to facilitate comparison to other calculations.