A study has been performed of the impact on performance of using low-e
nriched uranium (20% U-235) or medium-enriched uranium (35% U-235) as
an alternative fuel for the Advanced Neutron Source, which wa initiall
y designed to use uranium enriched to 93% U-235. Higher fuel densities
and larger volume cores were evaluated at the lower enrichments in te
rms of impact on neutron flux, safety, safeguards, technical feasibili
ty, and cost. The feasibility of fabricating uranium silicide fuel at
increasing material density was specifically addressed by a panel of i
nternational experts on research reactor fuels. The most viable altern
ative designs for the reactor at lower enrichments were identified and
discussed. Several sensitivity analysis were performed to gain an und
erstanding of the performance of the reactor at parametric values of p
ower, fuel density, core volume, and enrichment that were interpolatio
ns between the boundary values imposed on the study or extrapolations
from known technology.