<p>This paper goes into detail on modeling done using the Monte Carlo N-Particle Transport Code (MCNP) by Los Alamos National Laboratory and the SCALE code system by Oak Ridge National Laboratory in support of the development of a Cryogenic Tracer Irradiation Facility (CTIF) at the University of Texas at Austin. The CTIF is an ex-core facility that uses the beam ports of a Training, Research, Isotopes, General Atomics (TRIGA) mk. II reactor as a location to freeze a loaded gaseous isotope. The solidified isotope has a higher density, increasing the reaction rate for neutron activation to a level comparable to what could be achieved with an in-core facility. The system was experimentally tested using several short irradiations and the results from these tests were compared with a documented in-core experiment to compare the two methods. The SCALE code system was utilized to predict activation rates and potential radiation dose hazards, while MCNP was used to estimate neutron flux at various power levels in the beam port and to provide a neutron energy spectrum. At 50&#xa0;kW of reactor power, the neutron flux predicted using MCNP was 2.86 × 10¹⁰ neutrons/cm²/s and the experimental value was 2.85 × 10¹⁰ neutrons/cm²/s ± 3.46% when the CTIF is located in BP2. Further modeling was performed to determine the effectiveness of the CTIF in other ex-core beam ports.</p>