Department of Energy (DOE) Oak Ridge National Laboratory Site Office prepared an environmental assessment (EA) for the Construction and Operation of the Stable Isotope Production and Research Center, Oak Ridge National Laboratory (DOE/EA-2136). The EA assesses the potential environmental impacts of a proposal to expand current stable isotope production capabilities at Oak Ridge National Laboratory (ORNL), facilitate efficient operations, help meet demand, and reduce dependencies for obtaining stable isotopes from foreign suppliers.