Automated ADVANTG variance reduction in a proton driven system

We discuss the use of the ADVANTG automated variance reduction program for shielding studies of a vault containing targets irradiated by cyclotron accelerated protons. Because ADVANTG is limited to neutron and photon models, our calculations proceeded in several steps. Neutrons and photons emanating from a sphere surrounding the target were saved to a surface source file. This file was used to define sources for the ADVANTG runs and as a source for subsequent Monte Carlo runs. Test runs were made to ensure the validity of each step. The final calculations using the ADVANTG produced weight windows ran much more quickly and gave the same results as a model using only importance splitting for variance reduction. (authors)