[en] Physics analyses have been performed to characterize the performance of the cold neutron source to be installed in the High Flux Isotope Reactor l at the Oak Ridge National Laboratory in the near future. This paper provides a description of the physics models developed, and the resulting analyses that have been performed to support the design of the cold source. These analyses have provided important parametric performance information, such as cold neutron brightness down the beam tube and the various component heat loads, that have been used to develop the reference cold source concept. (author)